OF " BRAR v N.QN CIRCULATING CHECK FOR UNBOUND CIRCULATING COPY UNIVERSITY OF ILLINOIS Agricultural Experiment Station BULLETIN No. 268 THE SUNFLOWER AS A SILAGE CROP COMPOSITION AND YIELD AT DIFFERENT STAGES OF MATURITY BY W. L. GAINES AND W. B. NEVENS URBANA, ILLINOIS, JUNE, 1925 CONTENTS PAGE INTRODUCTION 407 OBJECTS OF THE STUDY 408 PLAN OF INVESTIGATION 408 RESULTS SECURED 411 Yield of Crop and Constituents 411 Mathematical Expression of Growth 415 Growth in Stalk of Sunflower and Corn 418 Growth in Seed of Sunflower and Ear of Corn 421 Significance of the Growth Constants 426 Composition of Crop 429 Yield and Composition of Crop as Ensiled 429 Comparative Yields of Sunflowers and Corn 434 Yield of Crop in Terms of Digestible Nutrients 435 Fertility Relationships 436 Thickness of Planting 442 Time of Planting 443 SUMMARY AND CONCLUSIONS 445 REVIEW OF LITERATURE 447 Investigations Dealing with Composition or Yield of Sunflowers 447 Crops Other Than Sunflower: Studies of Composition, Yield, or Feeding Value, at Different Stages of Growth 449 Conclusions from Review of Literature 452 LITERATURE CITED.. ..454 THE SUNFLOWER AS A SILAGE CROP COMPOSITION AND YIELD AT DIFFERENT STAGES OF MATURITY By W. L. GAINES, Chief in Milk Production, and VV. B. NEVENS, Assistant Chief in Dairy Cattle Feeding INTRODUCTION A widespread interest in the possibilities of the sunflower plant as a practicable crop has been aroused in sections of this and other coun- tries where the plant has not previously been grown on a commercial scale. This interest has been occasioned largely by the possibility of the substitution of sunflowers for corn as a silage crop, particularly in those sections in which corn does not grow satisfactorily on account of climatic factors or the attacks of insect pests. The utilization of sunflowers for silage in Illinois has not been attended, up to the present, with a full measure of success. Several problems have arisen with regard to the keeping qualities of the silage and with respect to its value as a feed for livestock, particularly dairy cows. Furthermore, there has been a variance in recommendations and in practice with respect to the methods of culture and to the time of harvest. It is obvious that any crop which shall hold an important place in the cropping system of a livestock farm must make some important contribution to the income of the farm, either as a cash crop or as a crop yielding a large amount of feed per acre. Among the questions which naturally arise in connection with the use of sunflowers as a silage crop are those regarding the methods of culture and stage of growth at which the crop should be harvested in order to give the maxi- mum returns in feeding value per acre. From a survey of the literature on this subject it was concluded that the lack of concordance in the results of sunflower silage tests reported by different experiment stations and individuals might be due to the fact that the sunflowers were ensiled at such widely differing stages of growth that the character of the silage used in some trials was very different from that used in others. Accordingly, an investigation was planned which it was hoped would solve some of the problems involved. A study of the composition and yield of the crop at different stages of development seemed essential to the determination of the stage at which the crop should be harvested in order to secure the maximum feeding value per acre. Such a study was therefore carried out as de- 407 408 BULLETIN No. 268 \_June, scribed in this bulletin. But since the chemical composition of the crop gives relatively little indication of the feeding value of the silage made from the crop, particularly as regards digestibility, palatability, and physiological effects, a study of these factors in the silage produced from sunflowers harvested at different stages of maturity was also undertaken as a necessary phase of the project. The results obtained in the study of the feeding value, composition, and digestibility of the silage are published in Bulletin 253 of this Station. The results of the study of the composition and yield of the sunflower crop at different stages of development are reported here- with. The results obtained in one season and on one field may, of course, not be duplicated under other conditions of season and soil. OBJECTS OF THE STUDY This investigation was undertaken for the purpose of securing in- formation on the following points: 1. The yield per acre of the sunflower crop in stalk* and seed at different stages of maturity, including the yield of the feed nutrients of the crop as commonly distinguished: namely, dry matter, protein, fat, crude fiber, and nitrogen-free extract, the ash being further consid- ered in some cases as to several of its elements, namely, aluminum, calcium, iron, magnesium, phosphorus, potassium, sodium, and sulfur. 2. The percentage composition of the crop, data on this point being of course essential to the yield estimates. 3. The effect of time and rate of planting on yield and composi- tion of the crop. 4. From the foregoing to ascertain if possible: (a) the state of maturity at which it is best to harvest the sunflower crop for silage; (b) the best time and rate of planting for silage; and (c) the amount and kind of fertility removed in the crop. PLAN OF INVESTIGATION A field of the Station farm at Urbana was utilized in growing the crop. The field, which had been subjected in previous years to quite heavy grain cropping, was about 40 by 80 rods in size and fajrly uniform as to soil (Fig. 1). The Mammoth Russian variety of sunflower (striped seed) was used. There was some slight mixture of a multi- headed variety. The main portion of the crop was planted May 18, 1921, in rows 3.38 feet apart and developed an average stand of one plant to 10.55 inches (14,662 plants to the acre). Three silos were filled from this "The term "stalk" is used to refer to the entire portion of the plant harvested, except the seed. 1925] THE SUNFLOWER AS A SILAGE CROP 409 main crop, one on August 13, another on September 2, and a third on September 21. The crop as harvested was weighed and sampled, and the samples analyzed. The resulting silage was later fed in comparison with corn silage. Bulletin 253 describes the way in which the analyses were made and the digestion trials conducted. The results from the crop harvested as silage gave data at three stages of growth, on differ- ent but comparable soil areas. A further analytical study of the main crop was made from field samples taken at random at ten- or eleven-day intervals thru the grow- ing period of the crop, after it had reached a height of four or five feet. For this purpose four consecutive rows (about eighty rods in length) near the middle of the main crop field were reserved. Samples were taken 65, 75, 86, 96, 106, 117, 127, and 138 days after planting. In FIG. 1. GENERAL VIEW OF SUNFLOWER FIELD This view gives a general idea of the field and the appearance of the crop at an early stage of growth, 49 days after planting. The field samples were taken from the center 4 rows starting 16 days later. (Corn at the extreme right.) selecting the plants for a sample, the first plant was taken at a pre- selected number from one end of a row, this number being different at each sampling period. From this plant as a starting point every one- hundredth plant was taken at the first sampling period, every ninety- ninth plant at the second period, every ninety-eighth plant at the third period, and so on down to the eighth and last period. This method of selecting the plants in the field was intended to give a random sample. The samples consisted of about sixty plants each. The .selected plants were cut six inches above the ground; the number of plants and their combined weight determined; the seeds separated (except at 65 and 75 days, when the seeds were not sufficiently formed); the seeds weighed and sampled; the stalk portion reweighed, cut with a power feed cutter, and sampled by the method of quartering. The subsamples of stalk and seed thus obtained were oven-dried at 410 BULLETIN No. 268 [June, 45-50 C, ground to pass a one-millimeter sieve, and preserved in glass jars for analysis.* Analytical Methods Employed in the Analysis of Sunflower Seeds and Resi- dues." "Owing to the difficulties involved in determining iron and aluminum in the presence of phosphates, it is desirable to explain briefly the methods used in obtaining the analytical results herein reported. "The ashing was carried out in platinum dishes to avoid the contamination in the glaze of porcelain dishes due to the presence of phosphates. In each case when new material was needed for analysis the percentage of ash was determined, so that the percentages of the various elements in the material would not be disturbed be- cause of the presence of varying amounts of unburned carbon. "In each determination one-half gram of material was used. Solution of the ash was obtained by using 5 cc. of nitric acid, Sp. G. 1.42, and hydrochloric acid, Sp. G. 1.19, diluted to 20 cc. This was evaporated to dryness in a platinum dish, filtered, and the same dilution noted above was added. The phosphorus was then removed and the iron and aluminum determined according to the method of Krug; 27 see also L. A. Cong- don and J. A. Carter. 13 Briefly, this method removed phosphorus as ammonium phos- phomolybdate. It was washed with ammonium nitrate water and the iron and aluminum was precipitated in the filtrate with ammonia in slight excess and as cool as possible. Boiling has a tendency to precipitate white molybdic oxid. The precipitate of iron and aluminum was redissolved in nitric acid and reprecipitated as above, a procedure which insured no contamination by molybdic oxid. d "The calcium was determined in the filtrate from the iron and aluminum in the usual way, with ammonium oxalate, and burned to calcium oxid, except that the am- monium oxalate was added in the cold to an acid solution instead of to the usual ammoniacal solution. The ammonia was then added in the cold, slightly warmed, and allowed to settle until the next working day. "This procedure naturally produced a fine crystalline precipitate and it was neces- sary to use the best grade of filter papers in order to obtain a clear filtrate. "Magnesia was determined in the filtrate from the calcium determination in the usual way. "The alkalies were separated in platinum by means of platinum chlorid. Solution was effected with hydrochloric acid, and barium hydroxid was used to remove mag- nesium in purifying the combined chlorids." Adjoining the main crop, at the same date (May 18, 1921), were planted eight rows intended as thin planting and eight rows intended as thick planting. The rows thickly planted developed stands averag- ing one plant to 9.79 inches and those thinly planted, one plant to 13.21 inches. *Analyses of the feed nutrients were made under the direction of Dr. O. R. Over- man of the Division of Dairy Chemistry of the University of Illinois. The methods of analysis prescribed by the Association of Official Agricultural Chemists were followed. "The analyses of the ash and this statement concerning them, were made by J. M. Lindgren, Chemist, Division of Applied Chemistry, University of Illinois. c "The true ash in each case was not determined, as some carbon always remained in the ash. This was necessary in order to conform with considerable work done previ- ous to the analysis of the ash, so as to conserve the alkalies." AUTHOR'S NOTE. The samples of the sunflower plants and seeds were ground in a steel mill equipped with hard steel grinding plates. The possible contamination of the samples by iron due to this procedure was not determined, altho in view of the large amount of iron present in the samples the contamination, if any, is believed to be relatively small. /925] THE SUNFLOWER AS A SILAGE CROP 411 A second planting of four rows was made on June 8, which devel- oped an average stand of one plant to 10.02 inches. This planting was severely attacked by rust, with the result that the yield was greatly decreased. A third planting of four rows was made on June 29. A very poor stand, one plant to 17.85 inches, resulted, owing to dry weather at time of planting. A fourth planting was made on July 20. This planting developed a stand of one plant to 9.53 inches. Yields of the "thick" and "thin" plantings were determined by harvesting part or all of the crop for silage. Yields of the late plantings were determined by the method of random sampling outlined above. RESULTS SECURED We may consider first the results with respect to acre yields of the main crop as indicated by the field samples. Percentage composition of the crop is the result of the quantitative growth relations of the plant, and while the qualitative data must be obtained before the quantitative estimates can be made, the qualitative changes are the re- sult rather than the cause of the quantitative relations. The qualita- tive results may therefore be logically considered after the quantitative results. YIELDS OF CROP AND CONSTITUENTS Table 1 shows the estimated yields per acre of the crop as a whole and of certain of its constituents as estimated from the field samples. The data represent the averages per plant of the corresponding field sample multiplied by 14,662 (the number of plants per acre). In the samples taken 65 and 75 days after planting, the seeds were not de- veloped at all, or not developed sufficiently to permit separating them. From later samples the seeds were separated and the data for the crop are the sum of the estimates for stalk and seed as separately determined. Eighty-six days after planting, the total quantity of seed obtained from the 60 plants constituting the field sample was insufficient to permit an ash analysis. The plants which were to constitute the last two field samples were selected on September 12, and cheesecloth tied about their heads at that time in order to prevent loss of seed by shattering or the depreda- tions of birds. Data from Table 1 are shown graphically in Figs. 2 and 3. The highest yield of crop is indicated at 86 days (Fig. 2), August 12, after which the green weight falls off quite rapidly, especially after 117 days, September 12. This decrease in green weight is largely due to loss of water, as shown by the fact that the dry matter of the crop increases up to 117 days. After 117 days there is a considerable decrease in dry matter of the crop as a whole. The dry matter in the seed, however, 412 BULLETIN No. 268 [June, IOP: ESTIMATED FROM SAMPLES TAKEN IN THE FIELD AT INTERVALS AS INDICATED ds per acre for the crop and certain of its constituents ujSoj};^ V a o. *00 OOcMO O->*"* OCCMO NONCCM oo oe NO * or. CM CM* OOONOO NOCMOO TfChM- I^ON OOOCN 4-CMI^ *<*" CM f mOin cMf^o ^mr^ -n-c^** r^r^-* inNO CO OO OO ON t^. ON ^(^CTv lor^OO t^f-M^ a < jn Jl n S f^v> t^ rsj CM ^ ON r^il^O ro-^f^ O VO ^C >ri-H f f^-^^-i -H *?; oor->o r^t^^S ON r^ O trj ^r * O uinipog ^^1^- oo Osooo r^r^M* <>\Ou^ M*oocs ^o^". OO r^ oo^-O ONCS^H O^^n t^t^^H -^ino uinis -SB10J Oi^ -4* OOI^LTJ -^oofS rsjr^i-^ iricTs-^ 1 OONO I^O O iof>C7\ MO'* O-*-* t>-\O-* ^^^^^ d r^i * Or^r^ 1^. C\ CM f^i -*f *o f^ r-l ^H ** o ^- *^ cso C"- snjoqd -solid t^ r^ oc ^*-I^ON so^^m ct^-f^ oocaovo ^^rMf^> f^r^ ^^ i^, ON * u->tn^M CSCN^ voot^ ocr^- i^iO O\ O 00 O OOfNO Or^oo ^fMt^ uini -S3USBJ\ r^ -^ C4 t^>^^\o O 1 ^*^ CM Q tN inO*'"* \or^t^ O * CS O O O\ mr->o\ ^ONro 1^ ON ^O ^t'fMr^ t^-* * i^>ui-*''irtiOT(<^r^c^ uojj * < O .en Orics CN-* vo oo >OCMOC tMC^ O QOCOO\OtOVOXC009^<^' uinpiir) 001^ rn ^^i-^oo in * so CN *" \o i^oou-j mi^oo SOO t^ \O-*O O'*'* OOOOO cst-O ^CSSO Lr 1 ,^ OC' OO* lO OfMfM f . c"iOO OCSf^ CMf^tn >^>t^ O CM 4 -HCKOvf^t- uinu -luinjY ** o * "i moioo Tfvoo \OCTv"i ocooe CMOO f~ t^ 00 OO O\ f. MII^. OOi-iO ^i-*LO -H cs .^.T.\OVOO r^t~- 1 B JL 3 o CX r^ OO i r-l vo (M OO tomCN m-^-O rv^\o O*om c^-*** r^r^t^t^r^r^.oocNt^i^*o CARBOHYDRATES 1 E >L ON VO O ON CN O \O NO "") -^ NO fN ^ r^ ^ f^ t^ NOt^m CM^* LOU-. O ONCON NOONio CMOOO O^i*n cnoOfM O '"' ^t" ^n r^ m NO CM 10 OO w> f^ r^j cs NO OO NO NO *"> csm ^^totot^u^i^NOu-jio-^m ,3 IN m ON NO NO m i i ^t* O CM rs ONCM m* ir^ ON* O -" CMCMC^C^mfnCMC^CMCM m r-^. i i NO NC f*^ C^ONC*I NO O NO t * * CM !*-< m ~*cM -i i* i imin * in NO TABLE 1. GROWTH OF THE SUNFLOWER C Expressed in yiel a'pnj^ mo fn m NO ON in -NO O Tf^oor* 1 ! cnfnNO m -iJ 1 in in in n M- ^in ^CMNO m* tn rMCM-^ J3UEUI XjQ Ccs f> oc ^ t^ <* . * in -^ O -^ ONOI^ cnl^ O oc t oo ON oo-*im NO ON CM ON rn cs Tf CM NO in * O J3JEM t^oo t^nO *"*oo NO'J'O i^o^ NCm < inNOi -rt^ ON O O O CN CN Tft^-cM NOOON -^inO t^- NO ^ < O oo CNinin ooinm cMmNC oc oc NO ooin^r NOCMON mNO ^1 *^ O CS 00 CM O ^t*^NO ' CM T* * CMCM mmmmcMmcMCM*^* J3JJBU1 HS3JJ ^ ^* en NO CN in in O ONI^NO cMroin moo * CMOOO in Q r^ oc *^ r^ f^ <-H in oo <* rn * in*^r^ * mm oco ocin-f NOOr^ oc (M i oc* ON CMOCO CM^-ON ^^^^.^^.^^^^ . "Nitrogen-free extract dOJD JO UBJ "o"o S-J-p"o ^"-TJ"H ^'-^"5 rj-^"^ =2-j~o d-ri'o jSJS c/5cniS tc;S c/5" 3 ^ cc/2^ toc^.5 tc.S SunuB|d UIOJJ SABQ inin NONO NO NO NO NO r^r^ r^r^ oooo NOr^ oooo C^ ON OO * * CMCM mm uei'wa CM*^ CMCM fMCM < CMCM CMCM m m CM 1 *- CMCM 1 1 CMCM 1 1 t OO II il ON ON 1 ' ' 1 OO t^ OOOO OOOO ONON ONON N 'iduieg * CM tT.J NOt^ OOON CM NOI-^ CM CMCM CMCM mm 7925] THE SUNFLOWER AS A SILAGE CROP 413 continues to increase thruout the period. The graph gives an idea of the distribution of dry matter between seed and stalk. The porportion of dry matter in the seed increases thruout, but at the point of high- est dry-matter yield, 117 days, there is less than one-fifth as much dry 40000 Growth or Sunflower Crop Be 9e toe m Days of+er Plan-ting '27 /36 FIG. 2. GROSS FEATURES OF THE GROWTH OF THE SUNFLOWER CROP Showing dry matter in the seed, dry matter in the crop (including seed), and green weight of the c/op. matter in the seed as in the stalk. In a comparable crop of corn grown for silage during the same season, the dry matter in the grain was equal to about one-half that in the stalk. (Table 8.) Fig. 3 shows the chief organic constituents (from a feeding stand- point) of the dry matter; namely, nitrogen-free extract, crude fiber,, protein, and fat. There are relatively large amounts of nitrogen-free extract and crude fiber and small amounts of protein and fat. 414 BULLETIN No. 268 [fune, >* ? I I I ! I ! 1 spun oj - Jdd p/3/A 1925~\ THE SUNFLOWER AS A SILAGE CROP 415 So far as the stalk is concerned there is evident a pronounced dis- position toward an accumulation of material up to 96 days and a loss of material after that time, except as to crude fiber. This period of loss marks the period of development of the seed, a loss presumably associated with this development. In the case of the seed there is a variable rate of increase thruout, except as to nitrogen-free extract. The increase in fat is the most striking of the changes. Fat is the chief storage product of the sun- flower seed, and the decrease in the amount of nitrogen-free extract is probably due to its use in the formation of fat in the maturing seed. Ash, as may be seen from Table 1, shows the same general relation as the organic constituents in its quantitative changes that is, in the stalk an increase followed by a decrease and in the seed an increase thruout. The same relation holds also with respect to the constituents of the ash, except in the case of aluminum in the stalk which, like the crude fiber in the stalk, continues to increase thruout. The crude fiber and aluminum of the stalk seem to perform differ- ently from the other stalk constituents. The crude fiber represents, from the standpoint of the plant, a structural material which is neces- sary to maintain both the form and position of the plant and is not readily utilized for the formation of the constituents of the seed. In a way, the crude fiber of the stalk is the most representative constituent of the plant which may be used to describe its growth as a physiological process. The growth curve of crude fiber in the stalk (Fig. 3) bears a general resemblance to the typical growth curves of annual plants and of animals. The same may be said of the aluminum of the stalk and of the various constituents of the seed (except nitrogen-free extract). While the present work was not undertaken as a physiological study of plant growth, nevertheless the production of farm crops is basically a problem of the physiology of plant growth, and this fact may justify an analysis of the data of Table 1 on the basis of one interpretation (Robertson's) of growth. MATHEMATICAL EXPRESSION OF GROWTH Robertson* 3 in his studies of growth, has used and attached much significance to the following equation as descriptive of growth phe- nomena: log- - K(t-.tJ (1) A x in which x and t are the variables, x being the growth accomplished at any time, t; A is a constant and represents the value of x at the completion of the growth cycle; t^ is a constant and equals t when x equals % A; and K is a constant. The equation has the invariable property of symmetry of its curve about the point of its intersection with the ordinate at t=t a , as a center. Up to this point the curve is convex to the base, and to the right of this point it is concave to the 416 BULLETIN No. 268 {.June, 1925] THE SUNFLOWER AS A SILAGE CROP 417 base. The lower limit of the curve is zero and its upper limit is the value of A. Theoretically these limits are never reached, but practically they are very closely approximated within a short range of t; the larger the value of K, the shorter the range of t. a TARLE 2. GROWTH OF THE SUNFLOWER AND CORN CROPS: VALUES OF THE CONSTANTS TO THE GROWTH EQUATIONS OF FIGS. 5-24 Data for corn are from Bulletin 175, Purdue University Agricultural Experiment Station Constituent Fig. A K ti SUNFLOWER Crude fiber in stalk 5 2700 .033 78.5 Crude fiber in stalk, 1st cycle Crude fiber in stalk, 2d cycle 6 6 2200 480 .042 .082 72.5 110 Aluminum in stalk 8 7.5 .033 97 Iron in seed 17 .235 .081 92 Calcium in seed 18 3.3 .050 97.5 Potassium in seed 19 12.5 .060 98 Phosphorus in seed 20 2 34 .054 100 Ash in seed 16 50 .053 100 Dry matter in seed 9 1450 .058 102 Crude fiber in seed 13 580 .060 103.5 Magnesium in seed 21 4.3 062 104.5 Sodium in seed 22 .55 .045 106 Protein in seed 11 240 .054 107 Sulfur in seed 23 5.2 .034 108 Aluminum in seed 24 4 .060 108 Fat in seed 15 560 046 108 CORN Crude fiber in stalk, 1st cycle 7 1030 075 66 5 Crude fiber in stalk, 2d cycle . . . 7 680 033 133 Crude fiber in ear 14 350 .047 95 Protein in ear 12 552 038 109 Dry matter in ear .... : 10 6000 .038 112 The above equation has been applied to the data of Table 1, Rob- ertson's method and tables being utilized in the first approximation to the values of the constants. The purpose of the present work and character of the data hardly seem to necessitate the further refinement of the estimates of the values of the constants by the method of least squares, as contemplated by Robertson's method. The constants of the equations as applied to the data of Table 1 and also to similar data by Jones and Huston 23 for the corn crop are given in Table 2. The data are shown graphically also in Figs. 5 to 24 inclusive. Time (t) is conveniently reckoned in days from the date of planting. Some days elapsed, of course, before the plants reached the height at which they were cut and subject to measurement. The zero point of t makes no "See pages 424-28 for further discussion of this equation. 418 BULLETIN No. 268 [/', difference, however, since the point of origin of the curve is virtually at 1=^. x is expressed as a percentage of A in the graphs. Growth in Stalk of Sunflower and Corn Crude Fiber in Stalk. Fig. 5 shows the observations on the crude fiber in the stalk of the sunflower and the equation and the curve de- scribing them as a single growth cycle. The curve gives a fair fit to the observations. The observations, however, suggest a small and rapid second growth cycle imposed upon the larger and slower first growth cycle. In Fig. 6 the data are treated from this viewpoint and a some- what better fit of the curve expressing the sum of the two growth cycles is obtained. The root mean-square error of the single cycle curve is 66 pounds, and of the double cycle curve, 40 pounds. The difference thus indicated is due primarily to the one observation at t=106; and if this observation is ignored, the errors are respectively 45 and 43 pounds. The observations might not warrant the assumption of a second growth cycle except that there are physiological grounds to ex- pect such a condition. The development of the seed head of the plant may be responsible for a second growth cycle in the present case, since there is a consid- erable amount of fibrous material in the head. (The seeds only were separated, the remainder of the head being included with the stalk portion of the sample.) The plant ceases to grow in height at about the time of pollination of the flowers (Reed and Holland*). Cessation of growth in height does not necessarily imply cessation of growth in diameter of stalk or amount of leaf and stem material. In view of the lack of sufficient data as to the crude fiber content of the head (minus the seed) it cannot be said, therefore, that growth in the head is entirely responsible for the second growth cycle. Fig. 7 presents similar data for the corn plant taken from Jones and Huston. 23 In this case the plants were cut at the ground level, in sampling. The crop was insured a regular minimum supply of water, by irrigation weekly if necessary. These data may" be very closely represented by a two-cycle equa- tion, assuming that the second cycle is at its maximum velocity at the last observation, 133 days after planting. It seems improbable that any material growth occurs after this time (October 8), but this would not preclude the termination of a second growth cycle before completion 'Reed and Holland 40 studying the growth of the sunflower in height in centimeters find the equation log = 0.042 (t 34.2) 254.5 -x to apply. Time (t) is reckoned in days beginning some time after planting, not defi- nitely stated, so that ti cannot be connected with the corresponding constant in the crude-fiber equation above. It may be noted that their K has the same value as in the present crude-fiber equation for the first growth cycle of the stalk. 1925~\ THE SUNFLOWER AS A SILAGE CROP 419 of its full capacity, as by frosts or by death of the plant from other cause. The data on the stalk include the husk, and the development of this organ may be responsible in whole or in part for the second crude- fiber growth cycle. According to the equations for the two cycles, the second cycle accounts for 24.8 percent of the crude fiber of the stalk (that is, all of the plant above ground except the cob and kernels) 133 days after planting. Schweitzer 45 gives data which indicate 19 percent of the crude fiber of the stalk as present in the husk 131 days after planting. Grindley* found 18 percent of the crude fiber of a 100 bushel crop of corn to be present in the husk. Accordingly, the development of the husk may be largely responsible for the second cycle. Assuming the data of Figs. 6 and 7 to represent the facts for the sunflower and corn crops, respectively, there is evident a pronounced and significant difference in the two crops. In the first, or vegetative cycle, the sunflower is slow-growing (low value of K), while the corn is quick-growing (high value of K). In the second cycle, associated with the reproductive activities of the plant, these relations are reversed, i.e., the sunflower has a short growth period and corn a long period. Also, if the indicated incomplete development of the second cycle for the corn stalk correctly represents the facts, the two crops are distinctly different in this respect. There is indicated, in short, a very marked difference in the two crops with respect to the relative development of their vegetative and reproductive functions. Further discussion of the significance of the differences in the constants of the equations from the standpoint of the genetic possibilities of the two plants and the bearing upon stock-farming practice is given below (page 427). Aluminum in Stalk. As mentioned above, aluminum is the only stalk constituent given in Table 1 which does not show a depletion in absolute amount coincident with the development of the seed. Some chemical difficulties were encountered in the aluminum determinations and this perhaps accounts for the irregularity in the observations (Fig. 8). One observation (10.86=144.8% of 7.5 at t=127) is omitted in the graph and disregarded in fitting the curve. The fact that crude fiber and aluminum alone do not undergo de- pletion suggests that they are in some way associated. It would be possible, as in the case of crude fiber, to treat the aluminum data as representing a two-cycle phenomenon, but the observations are so irreg- ular that the simple curve only is used. Treated as representing a single cycle, they may be compared with the crude-fiber curve of Fig. 5. The two equations have the same value of K, but quite different values of t t . Aluminum in the stalk is directly proportional to the crude fiber of 18.5 days preceding. Assuming that it is associated with the crude fiber, the lag in its appearance supports the idea that it is not a neces- MJnpublished data, Illinois Experiment Station. 420 BULLETIN No. 268 [June, . (X) (XJ 1925~\ THE SUNFLOWER AS A SILAGE CROP 421 sary constituent, but rather an unessential accumulation collecting mechanically according to the volume of tissues represented by the mass of the crude fiber." Growth in Seed of Sunflower and Ear of Corn Growth of the seed differs from growth of the stalk in that all of its constituents as given in Table 1 (except nitrogen-free extract) con- tinue to increase thruout the growth period. Dry Matter in Seed and Ear. Data for dry matter in the seed of the sunflower are given in Fig. 9, and for comparison Jones and Huston's data for the dry matter in the ear of the corn crop are given in Fig. 10. The value of K for the sunflower is much greater than for the corn, that is, the sunflower has a much shorter period of growth. It is necessary in interpreting the corn data, on the basis of the equation used, to assume that the ear is potentially capable of a considerably greater' growth of dry matter than is actually realized. Protein in Seed and Ear. The data for protein are presented in Figs. 11 and 12. Comparison of the equations and curves leads to en- tirely similar deductions as to the differences in the two crops, as in the case of dry matter. Crude Fiber in Seed and Ear. The data for crude fiber are given in Figs. 13 and 14. The differences in the equations and curves in this case, while of the same kind, are not so marked as noted for dry matter and protein. It may be noted also that whereas in the case of dry matter and protein the values of A are considerably greater for corn than for the sunflower, this order is reversed in the case of crude fiber. Crude fiber is not, however, a desirable stock feed and 85 percent of it in an ear of corn may be eliminated by the simple and common pro- cedure of shelling the corn. It is not commercially practical to elimi- nate the crude fiber of the sunflower seed for stock feeding. Fat in Seed. Fat or oil is the principal product stored as reserve nutritive material in the sunflower seed. The growth of the seed in fat is shown in Fig. 15. In order to reconcile the observations and the growth equation used it is necessary to assume that t a is considerably delayed for fat as compared with the other constituents of the seed, and that the growth process is terminated before its normal comple- tion. In this respect there is similarity to the growth of the ear of the corn crop in various constituents as above noted. This peculiarity may have some significance in connection with the possible improvement *The possible association of aluminum with crude fiber might be investigated in the seed of the sunflower. The seed contains some aluminum and a large proportion of crude fiber, nearly all of which is in the shell of the seed. The shell can be readily separated mechanically and determination of the accompanying separation of aluminum might give some light on the association of the two. The ratio of aluminum to crude fiber is much less in the seed than in the stalk. 422 BULLETIN No. 268 [June, I 1 fXJ \ tJ3& -"d "77 OVZ j"> 4ufj*j 1 $ T- 1925} THE SUNFLOWER AS A SILAGE CROP 423 (X) Jit? -"<> f t7 oes y (xj 424 BULLETIN No. 268 [June, 7925] THE SUNFLOWER AS A SILAGE CROP (X) LJJ.MOJJ 426 BULLETIN No. 268 [/"<", of the sunflower as an agricultural crop. The growth in fat is undoubt- edly associated with the depletion of nitrogen-free extract noted in Table 1. Ash and Mineral Elements in Seed. Data for the ash are given in Fig. 16, and data for the elements of the ash are given in Figs. 17 to 24. The figures for the elements are given in order of increasing value of t 15 as in Table 2. The growth in iron (Fig. 17) seems distinctly different, in that it is accumulated apparently at a very early stage of growth of the seed. It may be noted that phosphorus (Fig. 20) has the same value of K as protein (Fig. 11). Protein is thus proportional to the phosphorus of seven days preceding. The observations on aluminum (Fig. 24) are very irregular. The value of K has been arbitrarily taken to be the same as that for crude fiber. Significance of the Growth Constants The comparisons made here between the sunflower and corn crops are faulty in that the crops were not grown under the same conditions. The corn in the Indiana experiments yielded 76 bushels per acre, which is considerably more than the yield that might be expected under the sunflower crop conditions. Environmental conditions affect the values of the constants, espe- cially A, in the equation used to describe growth. The significance of the constants becomes clearer by considering the derivation of the equation. Derivation of Growth Equation.* The equation is that expressing the course of a monomolecular chemical reaction which is autocatalyzed. The velocity of such reaction at any moment is proportional to the product of the amount of untransformed and transformed material. It is expressed as: V-Ma-x) (2) dt where a is the amount of reacting material to start with; x is the amount converted at any later time, t; and kj is a constant. It is apparent that the greatest velocity will be at the time when x=a x= 1 / 4 a. This is accordingly the point of inflection in equation (1). Equation (2) inte- grated gives: log = K(t- tl ) (3) a x in which K=k 1 a and t t is the time when x=% a. 'Adapted; see Robertson 43 for fuller treatment. 1925~\ THE SUNFLOWER AS A SILAGE CROP 427 This pertains to the forward reaction. Where the reverse reaction proceeds sufficiently so that it needs to be taken into account we have: -^ = k 1 (a-x)-k 2 x 2 (4) dt k 2 being the velocity constant of the reverse reaction, and other notation as above. Equation (4) rearranged and integrated gives: log =K(t- tl ) (1) A ~ x i, KJ a that is, the equation used, and in which A = , other notation as above. In applying equation (1) to the expression or interpretation of growth phenomena it is obviously inadequate to include the entire meta- bolism of the organism involved in growth. It is conceivable, however, that it may represent some one reaction upon which the other growth activities depend, and being the limiting factor in the velocity of growth serves to determine, as well as to describe, the whole growth process. Genetic Significance of the Difference in the Constants. In equa- tions (2) and (4) ^ and k 2 are constants, unaffected by the value of a and specific for the particular chemical reaction concerned. In the liv- ing organism, a is presumably subject to some modification according to the level of nutrition. Accordingly A in equation (1) may vary considerably owing to the nutritional environment, but K/A(=k 1 -|-k 2 ) a should be theoretically unaffected by the nutritional level and should afford an index of inherent growth qualities of the organism. The farmers' practical interest, however, in the sunflower and com- peting crops is in the yield per acre, that is, A itself in the equations as above applied. But in K/A, a large value of A tends to give a small value of K/A. A large value of K gives a large value of K/A, but a large value of K means a short growing period, which is associated with a low yield. That is, K/A as a specific constant varies inversely with the crop yield, as between different species or varieties. If K/A is a specific constant, independent of environment, then its reciprocal, A/K, is likewise a specific constant independent of environment and affords an equally fundamental index of inherent growth limitations. The ex- pression A/K has the advantage (for the present purpose) of varying directly with (not necessarily in exact proportion to) the agricultural *In the equations above- K = kia and A = . Hence K/A = k, + kz. See Robertson, page 39. 428 BULLETIN No. 268 [June, value of the crop. Where K/A is a specific growth velocity constant, A/K is a specific growth capacity constant. Comparison on this basis theoretically eliminates the effect of environmental differences. The constants A/K for the sunflower and corn crops as derived from the foregoing growth equations are given in Table 3. From Table 3 it appears that the sunflower is preeminently a stalk crop and a crude-fiber crop, while the corn is preeminently a grain crop. When the crude fiber in the stalk of the sunflower is compared with that in the corn, the sunflower is found to have a much higher value than the corn (440:165=2.7:1). When the dry matter in seed and ear are compared, the sunflower has a much lower value than the corn (250:1579=1:6.3). Again, as to the ratio of crude fiber TABLE 3. COMPARISON OF SPECIFIC GROWTH-CAPACITY CONSTANTS OF CERTAIN CONSTITUENTS OF THE SUNFLOWER AND CORN CROPS A/K x 10 2 Sunflower Corn Crude fiber in stalk a 440 165 Crude fiber in seed or ear 97 74 Dry matter in seed or ear 250 1579 Protein in seed or ear 44 145 "Weighted average of first and second cycles. in stalk to dry matter in seed or ear, the sunflower is much higher ( ~^: ' = 17:1 1. This is striking evidence of the inherent superiority of the corn crop as a stock crop. Possibly the sun- flower is better fitted to survive, if it were only a matter of natural struggle for existence, but as a cultivated crop the corn is evidently much more highly improved.* Undoubtedly the sunflower may be much improved by breeding and selection, but starting with its apparent inherent handicap of running to stalk and crude fiber, it would seem to have little prospect of ever competing with corn even as a silage crop, where conditions permit the growing of corn. As a seed crop, the sunflower has the further unfavorable features of a very limited time when it may be harvested without excessive loss of seeds by shattering and the difficulty of harvesting and storing the seed. As indicated by the data of Tables 2 and 3, the sunflower, as com- pared with corn, produces both absolutely and proportionately to the other constituents a very large amount of crude fiber. The crude fiber of farm crops tends to decrease somewhat in digestibility as the crop grows mature, reducing the palatibility of the crop as a feed. Herein, "Possibly the growth-equation constants as used are not entitled to the significance implied in the present treatment. The proof of their value is to be found in a wider application of the method under various conditions and a critical scrutiny of the results as to their rationality and usefulness. 1925} THE SUNFLOWER AS A SILAGE CROP 429 apparently, lies the reason why the sunflower should be harvested, for silage, at an early stage of maturity if the best use is to be made of the crude fiber of the crop. Corn harvested at an early stage of maturity may develop an objectionable degree of acidity in the silage, but the sunflower does not seem to be subject to this disadvantage of early harvest. COMPOSITION OF CROP The percentage composition of the fresh green crop is given in Table 4, and the percentage composition of the dry matter of the crop is given in Table 5. The most striking change is in the water content which, starting at 89 percent 65 days after planting, falls off gradually at first and then very rapidly after 117 days. Up to 117 days, there is an excessive amount of water in the crop for silage purposes. Placed in the silo in this condition, there is a loss of plant juices by seepage from the silo. It is therefore advisable to allow the plants to dry to some extent in the field after cutting them and before hauling them to the silo. After 117 days the water content falls off so rapidly that ten days later it is too low for best preservation in the silo. The changes in percentage water content of course affect the per- centage content of the other constituents. Changes in these are best considered, therefore, on the basis of the composition of the dry matter as given in Table 5. It may be noted that the proportion of fat in- creases markedly in the seed as growth proceeds. The proportion of crude fiber also increases markedly in both stalk and seed. The other constituents ash and nitrogen-free extract, particularly the latter decrease with maturity. The crude protein of the stalk likewise de- creases with advancing maturity. YIELD AND COMPOSITION OF CROP AS ENSILED Samples of the main crop as it was being ensiled at three different stages of maturity were obtained by taking small random samples from the silo during the filling process. These samples were collected in cov- ered milk cans. At the close of the day's run, this large composite sample, having a bulk of fifteen to twenty-five gallons, was subsampled and the subsamples dried as usual. The analyses of these samples, together with calculations of yield of the crop per acre, shown as Tables 6 and 7, serve as a check upon the field samples taken about the same dates and from which the composition of the crop was determined, as presented in Tables 4 and 5. Thus sample No. 5 corresponds closely to the calculated results from the combination of samples 3 and 4; sample No. 11 to samples 8 and 9; sample No. 25 to samples 26 and 27. It will be noted that the results obtained by the two methods of sampling are in general agree- ment. The yield of fresh matter in the crop is lower in two of the cases 430 BULLETIN No. 268 S i s "I >i to v u 2 S b! o. 5 e w at Cd s 5 o f s t^. e- ^ s P. u oo cs oo u-, t-OOVO f^-* O so O mom < t-^ O o' 1000 ^"pN^ NO t^- ON (^- vO ^ in ininr^- CM ^f ^** ^Jc*4CM 00 TC n T^moo C^OON ^t* in m CMOCM r"^ OCM ON in ***< int-~m vOO^O OO'NOOO ^NOm \omt-' o\ in ON CM^OO O OOO CMln O 00 NO- CM CM ri CM CM NO o * OOOOON ? o, O\oo\O * C-OC <~l c (nooo O*n r^ootn in incN ooin\o C oo OO O o*'* UMO i^>i^> 10 1^ i/l t/^ CS tn -^* ^< C IAI tA>u^ in io i^)U^ LTJ to 10 wi loin O OO to O S OOO OO OO* OO OO c'o* Of^QOONC vo^O ON CN OO -- oo oo oo t^o\ \ooo\o 00 OO OOOO OOOO OOOO OOOC OOOO OOOO 00 O\O\ OOO TTT"i" TT TT i-T 11 11 ^ ti 111 10 10 u-j 10 10 10 io l o 10 *o 'sC ^C I s -* t** I s *. tnt> OOON C CMCM CMC CM oo ONin 1925] THE SUNFLOWER AS A SILAGE CROP 431 S-a u & o O u 5J a SgS 35; S =S8 35S -S3 8=5 * is-oo ~~P u. c^ c* r^ (** C^-^CTN , s o *j .2 rt w S 333 !j?g 2;?.^ S^i? S = S KSSv 00 0004 ^04 -u 04 vo VO vo OOOvf*- Os^f^ O-. f> VO O VO <*1VO"1 r^ u~o4 OvOCO> U v J 9 S SR5! ^SS S^S L?c-S SSS ^S goo goors. *T *J vc rs. >P"i oomf- uir^t^ oo Q ui lor^ov in u~. 01 VD Q Q <. " u vo ^^j^ *g,f-. ovocvo ^oo- 03- fs-g- K S3 rt 5* a * sss ass sss RSR , ss* 55 as s?is ^ ' 3 *e I 1 *-. oot^CN oo i^ cs oocMt^i r^c^^f t^ooON csoo^o R ^ 8 = S 3* . __ _ _ .0 r>i vo c^i^f Ot^^o ^t^-u^ cs^o^K r* < ^ i C\ ^"CT\ 2 SS 3 < t*-v . r- i i o r- i <* O f^O r^r^.O C-^ON Or^t>- CO 0-04 0-t^-H 2g. u h 1) O -*t) *!> *!) "!> *W ."*) "o "o"o "o"5"c ^ ^ MW^ wc^ a>c/3 u;c^ vjoo^ C^M^ ^ ^^ ^^^ ill .2 & c Q*S- ^0 d do do do do do dc 04 i/T* rrt>f~ |l 5^10 tovovo vovo vcvo r^sfs. fs.rs. oooo 5\O IS.OOOD OvO 1 . GO 01 04 f>ro "o oo rs. ON VOQO vo O OOO\ vOfs-O- 2 n c CJ5 a oo oo oooo ooao oooo or. oo oooo oooo T T TT TT TT TT TT ~T io\oinu-t m^ i^urt LDLA tnu-> w-.^ 00 ONOv OOO 1 0404 040404 vo L III vcvo rs.fs.rs. u "S-d CO 04 *>* VOr~ 00 O\ 04 VOts. 0( 04O4 OIO4 f*tO oo oiX Ovo'fs- 04 O4m cnmcn 432 BULLETIN No. 268 [June, x -> H Q. % U w >O u rt UH a r-< CO CN 4s I'll o oo CO oo so oo O> oo O so 5 w S J: > x /-I Q> oo CN co O> so co CN CO oo CO o CN u u g J CO CN so CN CN CN * "O 'S 2 o O oo OO OO so r~^ so 1 CO O SO CN 1 O co (-, Q cj E CN O so r~- 1 so CN 1 oo SO-H W) OO ^ O co co CO CO SO CN |8 . i oo co CO OO CO oo o OO vo r~- oo CO CO SO CO CO oo * a U V V oo It CN o> CN ON B ]j ^ 00 oo oo oo OO "o, S>v 1 1 1 1 1 u ad 1* C/5 ^ O-* CN CN 1925] THE SUNFLOWER AS A SILAGE CROP 433 S. o - s W C8 Q .S i "O " oo cs CS OO OO CO SO -H CN >o cs r^ rt "O n ^1 1^ cs JC f^?S S 8s (_, n I: L sB r^ so oo oo -H *< w-> oo cs r^- ON i-i co so so f *"<*< co co u , 11 *-" * Q Tf o O> O> O CN i i co >o r^ o> co t^. 10 SO CO CS cs <*< oo cs i i SO 10 <}< -H CS CS CO CO * * B.S "O 1) 3 -> u O CS O O CN y matter SO OO D V, OO 00 OO OO OO oo oo oo oo oo Q s> 1 II 1 I 1 1 1 1 1 o. c/? ~ " CS CN 2^ cs cs 434 BULLETIN No. 268 [June, where the yields were calculated from the weights of the loads delivered to the silo and from the samples thereof, than the yields calculated from the field samples taken at corresponding dates and shown in Table 1. As the field was fully a mile from the silos, it is believed that these differences are due, in part, to loss of moisture from the plants during the brief time they were exposed to a drying atmosphere after they were cut and before they were weighed. Another contributing factor was that the plants as harvested for the silo were cut at a greater height from the ground than when obtaining the field samples. COMPARATIVE YIELDS OF SUNFLOWERS AND CORN A ten-acre portion of the field upon which the sunflowers were grown was planted to field corn. The manner of planting was that usu- ally followed in growing the crop for grain, that is, planting in rows 3 feet 6 inches apart and in hills 3 feet 6 inches apart in the row. The crop yielded somewhat less forage per acre than corn grown for silage TABLE 8. COMPARATIVE YIELDS OF SUNFLOWERS AND CORN* Pounds per acre Substance Sunflower Con i crop crop Field A Field B Fresh matter 34 945 19 567 14 340 Dry matter 8 248 5 935 4 808 Crude ash 901 352 288 Crude protein 612 531 414 Crude fiber 3 119 1 275 985 N-free extract 3 184 3 638 2 991 Carbohydrates 6 303 4 913 3 976 Crude fat 432 139 130 a Data for sunflowers taken from Table 1; samples harvested September 12. Data for corn are from a crop grown for silage in the same season, yielding 39 bushels of shelled corn on Field A and 31 bushels on Field B. Corn crop harvested August 25 to 31. (drilled) for the same season, only 5.93 tons per acre of fresh matter containing 4,113 pounds of dry matter. These data are not considered representative of corn grown for silage. Data for two other fields of corn, grown the same season for silage purposes, are considered more representative of the nutrient yield of silage corn, and are therefore brought together in Table 8 for comparison with the data of the sun- flower crop. The sunflower crop, at the time the yield of dry matter had reached its maximum, contained 50 percent more dry matter than the corn. The sunflower crop at that stage had declined greatly in water content, but even then the ratio of dry substance to water was about 1:3.2, whereas in corn it was 1 :2.2. 1925] THE SUNFLOWER AS A SILAGE CROP 435 The differences in the character of the nutrients in the two crops are well illustrated in this table. The yields of crude fiber and nitrogen- free extract of sunflowers are about equal in amount, but in corn the ratio of the two classes of nutrients is approximately 1:3. The yield of crude fat in the sunflowers is much greater proportionately than that in the corn crop. Losses in Leaves. Evidence of the loss of dry matter from the sunflower crop was sought by a study of the composition of living and dead leaves of the same plant. Eighty-four fresh green leaves and an TABLE 9. COMPOSITION OF THE DRY MATTER OF FRESH GREEN AND DEAD SUNFLOWER LEAVES Expressed in percentage of the dry matter Ash Crude protein Crude fiber N-free extract Crude fat Fresh green leaves 18.06 17.25 12.28 47.06 5.36 Dead leaves 17.94 15.59 17.38 44.04 5.06 TABLE 10. AMOUNTS OF VARIOUS CONSTITUENTS PER 100 SUNFLOWER LEAVES Expressed in grams Dry matter Ash Crude protein Crude fiber N-free extract Crude fat Fresh green leaves . . . Dead leaves 306.4 191.5 55.3 34.3 52.8 29.9 37.6 33.3 144.2 84.3 16.4 9.7 equal number of apparently dead, dried leaves were collected, the same number of each kind being selected from each plant. Care was taken to choose leaves corresponding approximately in surface area. The leaves were weighed, dried under the same conditions as the field samples, and submitted for analysis. The results of these analyses and calculations relative thereto are shown in Tables 9 and 10. The dead leaves contained 62.5 percent as much dry matter as those which were living at the time of collection. The dead leaves were relatively poorer in crude protein and nitrogen-free extract, but higher in crude fiber than the others. These data do not, however, necessarily prove that sunflower leaves, following cessation of growth, lose their nutrients thru weather- ing, since it is possible that some of these constituents are withdrawn to other parts of the plant. The severe attacks of sunflower rust may have rendered the infected leaves subject to losses by weathering. YIELD OF CROP IN TERMS OF DIGESTIBLE NUTRIENTS One of the most important criteria of the value of a crop for silage purposes is the yield of the crop in terms of digestible matter. The data obtained in this study include the yields per acre of total crude nutri- 436 BULLETIN No. 268 [June, ents. Portions of the main crop were ensiled at three different stages of development and studies were made of the feeding value of the silage produced (see Bulletin 253 of this Station). The coefficients of digesti- FIG. 25. CUTTING SUNFLOWERS IN THE FIELD Showing condition of the crop at the first stage of maturity, as harvested for silage 87 days after planting. The crop was cut by hand so as to secure a more accurate determination of the crop yield. The yield per acre was 17 tons (85 percent water). bility of the silage which were obtained in those studies were applied to the data obtained in the field studies and thus the yields of digestible nutrients per acre were calculatetd. The results are presented graph- ically in Fig. 26. Marked increases in yields of digestible crude fiber and digestible crude fat were obtained in the later harvests, while there was a slight falling off of the digestible crude protein and a marked decline of the nitrogen-free extract. By postponing harvest as long as practicable there was a gain of about 9 percent in yield of total digestible nutrients per acre. It is believed, however, that the method of determining the amount of digestible matter in the crop at the time of the third harvest, namely, the application of the coefficients of digestion secured from the silage produced from the second harvest, very considerably overestimates the actual yield of digestible nutrients at that stage. The results were cal- culated in this manner in order to give a comparison of the yields of digestible substance at these different stages. It is likely that the actual yield of digestible matter at the time of the third harvest was less than at the second. For a further discussion of this subject, see Bulletin 253. FERTILITY RELATIONSHIPS The extensive use of sunflowers as a silage or seed crop would make it very desirable to have information regarding the fertility rela- tionships and soil requirements of the crop. The comparatively small amount of information at hand regarding these phases of sunflower cul- 1925'\ THE SUNFLOWER AS A SILAGE CROP 437 ture made it seem advisable to obtain detailed information regarding the amounts of the various ash elements in the crop. Q-IZ-21 9- I -'21 9-22-ZI Crude Crude N-Free Ether xtr. Total Prote/n F/ber Extract x8% D/'g Nut. FIG 26. YIELDS OF DIGESTIBLE MATTER IN SUNFLOWERS HARVESTED FOR SILAGE AT THREE DIFFERENT STAGES OF GROWTH Calculations are based on digestibility of the silage as determined with dairy cows. Fertilizing Elements Removed. The amount of the fertilizing ele- ments removed from one acre in the sunflower crop is shown in Table 1. It is very evident that there is a rapid increase in the crop of some of the elements, notably potassium, calcium, and nitrogen during the first part of the period of observation, and almost as rapid a decline in the latter part of the period. Magnesium and sulfur show trends in the same general direction. 438 BULLETIN No. 268 {]unt, The sunflower crop removed a very large amount of ash per acre, a total of 900 pounds as a maximum. The element potassium com- prized about 141 pounds of this, while calcium followed with 119 pounds, magnesium with 54 pounds, sulfur with 30 pounds and phos- phorus with 10 pounds. The amount of nitrogen in the crop was about 98 pounds per acre. In terms of fertilizers of the best grade, these amounts are approximately equivalent to: potassium sulfate, 335 pounds or kainit, 1,420 pounds; sodium nitrate, 600 pounds; limestone, 300 pounds; rock phosphate, 110 pounds. Fertilizing Elements in Seed. The amount of nitrogen and ash re- moved from the soil in the seed of the sunflower crop was very much less than that in the stalks. Nitrogen was present in the seeds in amounts equal to about one-half to two-thirds that of the total ash. Potassium far exceeded in quantity the other mineral elements, being nearly equal to that of the sulfur, magnesium, calcium, and phosphorus combined. Ash Constituents per Ton. The yield of sunflowers per acre is of course dependent upon soil, climate, and other factors, and is therefore subject to variation. Hence, the yields of ash constituents have been expressed in terms of their amount per ton of fresh matter and per ton of dry matter, of the stalks, seed, and whole crop. These data, shown in Tables 11 and 12, bring out the fact that the ash formed a larger part of the dry matter of both seed and stalk during the immature stages than during the more advanced stages. This change was gradual, but quite marked with the principal constituents, potassium and calcium. Some of the other elements show the same tendency, altho this is not so pronounced, especially in the seed. Composition of the Ash. It was shown that there was a pro- nounced variation in the proportions of the organic constituents during development of the crop, but this variation does not, in general, hold to so great an extent for the inorganic constituents (Table 13). The most notable exception to this condition is in the case of aluminum, the de- terminations of which seem to indicate a gradually increasing propor- tion of this element during the growth of the crop. The figures for iron in the early samples are lower than in the later ones, and the data for sodium lack uniformity, but upon the whole the data indicate relatively little change in the proportions of the ash formed by the other elements during the growth period studied. Potassium comprized one-sixth or more of the total ash of the crop and about one-fourth of the total ash of the seed. Calcium was the second greatest ash element of the crop, but the seed contained only one-half as much as the stalk portion of the crop. Magnesium, sulfur, and phosphorus followed in magnitude in the order named, in the total crop, but the distribution in the seed of the fully ripe crop fol- lowed the order potassium, sulfur, magnesium, calcium, phosphorus. 7P25] THE SUNFLOWER AS A SILAGE CROP 439 2-c C^l ^^ ^5 "^ OO ^* V O "^ ^xt 4 'O ^xt* V O ^O "^ O * CS CS OO CS H S OC ~H \O ^ *^ O O OS CO O -< O O ^ ON 1^ NO s^^s Os *o ^o r*^ ON r^> \& so ^^ ^^ NO t^- O OO O NO OO w-> CS _ . . ^ . . CN- CS -* 1 CS CSUOCO 01 -j s 8 : : R2S asa jj 8s ,,,- OO NO OO 05 M H ^H O CO-- <^)NO l o ONO CSO oo r^ -H Tf CO |s ^y O to vo NO r-or-. i^-^t^ oor^oo MM*N U^Tf^ X b. " o M 00 Tt< CM O ON CS ON 04 O I- 00 -H sss Kg;- w .e CS CN CS-- CS CS CS I---HNO ON co ON ^^2 s 1 r U oo ^^ ^^ f*} *^> fN rs ^* Os c^ ^^ "^ S2S8 ON CS OO s *3 2 c H; '-5 o U S r in rr d| ? 5 , . . ss ?SK a!J8 Rg ON NO f 1 ^ H CS CS .1 u _) w> TJ<.- ON ON OOOONO Ocooo O -i.- O-^O CSOCN 'fCSCO ON O . c U II ? OS M i cs co * Nor^ OOON -^cs CS CS NO r- CS CS CS COCO 440 BULLETIN No. 268 w c K C W >, t -5 < u- ? 5 2 Q b U O. = en CS CS T(< O OO **< OOOO CSSOO OCSCS O >* O co - ' <*< co oo rf O in co oo in oo ON co oc ON co ^f *F CN ON * cs r** ^H rf r^ ^H cs so ON oo so in CN CS CS CSCSCSCNCNCSCS I-HI-I O cs r-~ i -H co Q cs ^ r^ *< <- -nsoin O CO * Tf Tf Tfi CS SO CO CN OO t^ O CO"' Tf CN O-- t^~sor^ OO-- r^ini >nsoso vnsoin ON r^ o <* -H co r^ ~ oo O' T}< ^H-. OooON < Tf i Ot^oo i i so O *OI CSCS-.CSl-l' I-HCS< I-HI-H-H CS . . r~- cs CN 1 1^- so ON in CS ON ON O ON ON ON r^o o-^cs sot^--H ONO-* 1 CS . ON * oo ON ON 1^ t^ ON rfi CS so O oo t^ SO CO -^ CO CO -H CO CO -H CO CS -H CS f.f. ~H OD tj\ Or^oo ONONON ^so^ ^fO\sO oo' 4< L^\ **!.. QQ in ^H in O so ^ ON *-+ co i * *< O ' Tf rf * cs m -H <*< in co co so CS cs in O ,. .. - ,sor^ cocsoo cssor~ > > * cs -NTfso CJ ON so r^ ^socs coinON co^foo 00^3^ VP T * < Tr! J3 .- -. v. ^ , r~- cs t^ in -n so co co oo >n in > N ' - -e O Q. O 4J .'! .*4) "fl> "4) >*1> **WC - -C -C " i ^C "^ ;G "rt JJ J3 ^ ^ c/?cn^ c/} on ! CS CO Tf 1925] THE SUNFLOWER AS A SILAGE CROP 441 Jj 8 .2 1 S m O U!fl U J> & 2 w o a o> p IB ON- O O rt so-- ONffON I-HOO ON CO _ ff- oo so t-- ON-- ONCN<- , i to i ON i ON C/3 CN SO CN CO t^ ff vo O CN CO SO oc O oo to ff ff CO so co co co r- CO CN ON CO CN ON co ff O o O "^ ON oo ff -H to oo ON O O vo o CN *< vo ON- O ON O H co CN cosoco -^ ON ff f^ooO O oo ONOOON tosovn OOONOO vooovo oo i ON O CN O- OOCNCN t-^ ff OO votoOO OOCNON ONOOO ON ff O- ^f to vo so iff CNOOON CNCNO COOOSO ON vo ~H CN r^ so i oo so vo so > i oo ON so VO OO I^SOI to to to TfTfto VO ft? SO votovo i so O i ON ON ONCNSO ON ~* co 60 O CN CN- ONCNff Ot^SO i ii i CN CNt^-O ONfff~~ sooosO vooovo ON i O ON O ' totol sOffso vosovo toooso VOONSO sooosO SOCOSO I^voto OOCNCN OOON SOCOI vor^-co t^cooN cNsor^ ooooo c^3 to i-H to <^j c-^ vo O CN vo co ^^ to ff i < CN to to to f- vo ff t-^ ff COSOCO CN so CN ff SO CO ^-.COCN OOONSO OOOOff OOVOCO OCNCN f^- ff so ON so r^- r^ ff ff ON ON to ^^ oo f^ Or--O i i so > i OffO -HCO'-H ONffoo J2 nj IS O to CN ON CN ON CN i r~- CN so vr> so oo -H ON -.Ooo- OO CN so co O OO so CN so CN ff ff ff CO t^- OH to rf CN CO o ff " so CN ON f^ '-' ON oo -H ON so CN C ' ff ^ ff -H "o ,0 ff vr> I OO^HSO CNt-^^* CNCNCN SOVOSO SOVO-H co r-~ t^- cNffco ffooco ffffff Offff i ON so CO ' CO CN vo CN SOCOSO t^ r^- 1^- vo ff Tf ff t^ CO I s I 0. eg -o -<$ P^ ^-C -C rt o rt 4> ^ n QJ ^ rt U -C ca 1J JC co V -C C enen cnen^ enon^ onen^ enen^ enen! 5^ so " so i CN CN 442 BULLETIN No. 268 [fum, A noteworthy feature of the sunflower ash, not commonly found in plants, is the presence of aluminum in significant amounts. Pal- ladin 35 states that "aluminum occurs in plant ash rather infrequently." Pfeffer 36 agrees with the above statement, for he says, "Aluminum, tho universally distributed, is present only in small amount in most plants, except in Lycopodium chamaecyparissus and L. alpinum, where it forms 22 to 27 percent of the ash." Jost 26 states, "Thus it would not be sur- prising ... if it turned out that aluminum, which forms 22 to 39 TABLE 14. EFFECT OF TIME OF PLANTING UPON YIELDS OF THE SUNFLOWER CROP COMPUTED FROM WEIGHTS OF RANDOM SAMPLES (TAKING PLANTS IN DEFINITE SEQUENCE) AND ANALYSES OF SUBSAMPLES THEREOF Pounds per acre Sample No. Date planted Date harvested Age of crop Distance of plants in row Part of crop Fresh matter Water Dry matter 28 1921 6-8 1921 9-24 days 108 inches 10 02 Whole... 20 214 14 989 5 225 29 . 6-29 9-24 87 17 85 Whole.. 13 193 10 943 2 250 35 ... 6-29 10-6 99 18 54 Whole.. 5 888 4 532 1 356 30.. 7-20 9-24 66 9 53 Whole.. 10 189 8 888 1 301 36 7-20 10-6 78 10 69 Whole.. 7 778 6 509 1 269 37 7-20 10-24 96 13.57 Whole... 4 345 3 117 1 228 Yield of the Constituents of the Dry Matter Sample No. Ash Crude protein Crude fiber N-free extract Carbo- hydrates Fat 28 687 560 1 971 1 847 3 818 160 29.. 384 336 661 808 1 469 61 35 167 160 545 435 980 49 30.. 232 272 297 474 771 26 36 170 192 352 517 869 38 37 143 176 353 496 849 60 percent of the ash of Lycopodium chamaecyparissus . . . and yet ap- pears in the minutest traces in most plants, including several other species of Lycopodium, has a special function to perform in these plants. Large quantities of aluminum occur in species of Symplocos and Orites (Czapek II). Jamano (Bot. Centrbl. 99, 2) found that aluminum was of service in the development of barley." THICKNESS OF PLANTING It was planned to secure data on the comparative yields of sun- flowers planted thickly and thinly. The main planting was expected to give a stand of plants 8 inches apart in the row, the thin planting 16 inches, and the thick planting 5 inches, but the results were as shown 19251 THE SUNFLOWER AS A SILAGE CROP 443 in Table 6, samples Nos. 5, 11, and 25 representing the first or main planting, No. 10 the thin planting, and No. 24 the thick planting. The differences in thickness of the plants in the various plots were too small to give conclusive results. TIME OF PLANTING The data shown in Tables 4, 5, and 14 include, under samples Nos. 28, 29, 35, 30, 36, and 37, data obtained from the plantings of sunflow- ers made at intervals of twenty-one days following the planting of the (T670J 5600 S-IS-^I Harvested 9-2Z-2/ 6-Q-2I 9-24-2/ 6-29-21 7-20-ZI Dry Crude Crude Matter Prote/n Fiber //-free Ether Extract Ext.x2%. FIG. 27. YIELDS OF CRUDE NUTRIENTS IN THE SUNFLOWER CROP, AS AFFECTED BY TIME OF PLANTING main crop, from which the bulk of the data is derived. Samples from the later plantings were taken in the same manner as from the earliest planting. Chief interest in a study of the best time for planting sunflowers is centered about the comparative yields per acre from sunflowers planted 444 BULLETIN No. 268 [June, at different times. These data are presented in Table 14 and illustrated in Fig. 27. The differences in yield of the various plantings is very striking. This is well brought out in a comparison of the yields of dry mat- ter, but the yields of the various constituents of the dry matter show FIG. 28. SUNFLOWERS GROWN TO STUDY EFFECT OF TIME OF PLANTING UPON YIELDS View of first, second, and third plantings on July 19; planted May 18, June 8, and June 29, respectively. FIG. 29. LATE CROPS OF SUNFLOWERS GROWN TO STUDY EFFECT OF TIME OF PLANTING UPON YIELDS View of second, third, and fourth plantings on August 22; planted June 8. June 29, and July 20, respectively. similar relationships. The dry-matter yield of the later plantings ex- pressed in proportions of that of the first planting, were five-eighths, one-fourth, and one-sixth. As is pointed out below, these proportions do not hold for the yield of all the constituents of the dry matter. The later samples varied somewhat in composition from the crop of the first 1925} THE SUNFLOWER AS A SILAGE CROP 445 planting. The yield of crude fat in the later plantings is materially less, particularly in the third and fourth plantings, because of the lack of seed development. Practically no seeds developed in the last crop, altho it was sampled as late as October 24. In spite of frosts severe enough to kill the corn plants many of the sunflower plants were still living at that time. Several factors seemed to contribute to the failure of the later plantings to produce yields equal to that of the early one. Dry weather interfered with the germination of the third planting, made June 29. The effect of this is shown by the distance of the plants in the rows being more than 60 percent greater than that of the first two plantings. The later plantings appeared to be more susceptible to disease than the first planting, for it was found in taking the samples that many of the plants had become partially decayed and, being broken over, were not in position to be harvested by the usual methods. Only a few plants of the third planting grew well-developed heads, and of these only a part matured seed. The plants of the fourth plant- ing had attained a height of about four and one-half feet on October 6, having shown practically no development since September 24. Most of these plants blossomed, but very few developed any seed. The composition of samples from the later plantings is similar to that of the samples from the first planting taken about the same num- ber of days after planting, except that the samples from the later plant- ings were higher in dry-matter content and thus higher also in most of the constituents. When compared upon the dry-matter basis, the later plantings were found to contain a greater proportion of crude pro- tein and ash, to be very similar in fiber content to the first planting, and to be lower in nitrogen-free extract. It is self-evident that the character of the growing season of any one year plays an important part in determining yields and also the composition of the crop. Seasonal differences affecting the yield and composition of the sunflower crops produced from seed planted at dif- ferent times during the same season were not taken into account in the present investigations. SUMMARY AND CONCLUSIONS Data on the yield and composition of a sunflower crop grown in 1921 were obtained from samples collected in the field at eight stages of growth and from the crop as ensiled at three stages of growth. These data pertain to fresh matter, dry matter, crude protein, crude fat, crude fiber, nitrogen-free extract, ash, and the elements Al, Ca, Fe, Mg, P, K, Na, and S; all in stalk and seed separately. The feeding value of the silage and digestibility factors were determined for the three stages (reported in Bulletin 253). Thickness and time of planting were also studied. A review of literature has been included, and data from Bui- 446 BULLETIN No. 268 [/MM-?, letin 175 of the Indiana Experiment Station, on the corn crop, have been used in making comparisons. Data from the field samples have been analyzed mathematically X (following Robertson) by use of the equation, log = K (t t x ), A x in which x is the growth accomplished at any time, t, and A, K, and t x are constants. Each of the constituents of the seed (except nitrogen- free extract) exhibits the reverse curve so generally characteristic of growth in animals and annual plants. In the stalk, crude fiber and aluminum only exhibit the same trend, the various other constituents undergoing marked depletion coincident with seed development. In the stalk of both sunflower and corn, growth in crude fiber is interpreted as a two-cycle phenomenon. In the first, or vegetative, cycle the sun- flower is slow-gr owing while corn is quick-growing; in the second or reproductive cycle, the reverse is true. The specific growth-capacity constants (A/K) of the two crops indicate comparatively that the sun- flower is inherently a stalk and crude-fiber crop, while corn shows a high development of the reproductive function and is inherently a grain crop. Consequently it is desirable to ensile sunflowers at a much earlier stage of growth than corn, since it is a general fact that crude fiber de- creases in digestibility with advance in growth, with an accompanying decrease in the palatability of the crop as a feed. Checks upon the method of field sampling used for. determining yield and composition of the crop were obtained by weighing and samp- ling the crop at harvest. The two methods are in general agreement, except that the crop was subjected to losses of moisture enroute from field to silo. Such losses were largely prevented in the field-sampling method. Sunflowers produced 50 percent more dry matter per acre than two fields of silage corn grown near-by. The yields of ash, crude fiber, and crude fat were very much greater in the sunflower crop than yields of these substances in corn. The corn crop, however, proved superior in production of nitrogen-free extract. The early death and withering of the lower leaves of sunflowers is considered responsible for the loss of nutrients, altho nutrients from these leaves may have been transferred to other portions of the plant. Results of digestibility studies conducted with silage produced in this investigation (Bulletin 253), when applied to the field data, indicate no marked increase in yield per acre of digestible nutrients after 87 days from the planting of the crop. The sunflower crop removed large amounts of fertilizing elements from the soil, the total ash amounting to 900 pounds per acre. The elements present in largest amount in the crop were, in the order of their magnitude, potassium, calcium, nitrogen, magnesium, sulfur, and phos- phorus. Aluminum and iron were present in samples of both seed and 19251 THE SUNFLOWER AS A SILAGE CROP 447 stalk in appreciable amounts, altho the possibility of contamination of the samples by iron during their preparation for analysis was not pre- cluded. The seeds were very rich in potassium and nitrogen, altho they contained less than 6 percent of the total ash of the crop. The relative proportions of the ash elements in the seed differed from those in the total crop. Marked reductions in the total ash in the crop occurred toward the close of the season. In contrast to marked changes in proportions of the organic con- stituents during growth, the changes in the relative proportions of the ash constituents studied were much less. Aluminum constituted a rather distinct exception to this. Studies of the effect of time of planting upon yield and composi- tion showed very pronounced decreases in yield due to late planting, and minor effects upon the composition of the crop. REVIEW OF LITERATURE INVESTIGATIONS DEALING WITH COMPOSITION OR YIELD OF SUNFLOWERS Amos and Woodman 1 of Cambridge University, England, report yields of 20 tons of sunflowers containing 18.5 percent of dry matter, while maize gave yields of 14 tons containing 17 percent of dry matter. Anthony and Henderson 2 report the composition of sunflowers at five different stages of growth. Their results show little progressive change in composition during growth, except that there is a tendency for a decrease in carbohydrate content and an increase in fat content. "Sunflower silage yielded much heavier per acre than corn silage." Atkinson and Nelson, 5 at the Montana Station, found little differ- ence between the yields of sunflowers (reported as silage) planted April 29 and those planted May 29 and June 4. Rows 36 inches apart gave slightly greater yields of green forage than those planted in rows 8 inches apart, and nearly double the yields of rows 42 inches apart. Yields of dry matter are not reported. Bartlett 7 compared the yields of Maine field corn, red clover, and sunflower heads, finding that the yields of dry substance were 4,224 pounds, 3,400 pounds, and 2,040 pounds per acre, respectively. The yields of fat per acre in the three crops were 156 pounds, 133 pounds, and 317 pounds, respectively. Blish 8 determined the composition of sunflower silage produced from sunflowers ensiled at different stages of growth. "The percent- ages of food constituents do not differ greatly in plants of various stages of maturity up to the point where seeds are formed and partially hard- ened. With advancing maturity, other things being equal, there is a slight increase in dry matter, protein, fiber, and digestible carbohy- drates." The Canada Experimental Farms 11 report yields of over 8 tons of sunflower heads per acre. They further find that the weight of the 448 BULLETIN No. 268 {.June, dry matter in sunflower heads was 3,767 pounds per acre when the yield of sunflowers (whole plant) was 7,219 pounds of dry matter. Holden 18 reports a greater tonnage of sunflowers than silage corn or field corn at the Scottsbluff, Nebraska, Station. Jensen 21 reports the yields of sunflowers over a five-year period, the seed having been sown each year on five different dates at one-week intervals. While there was considerable variation in the results, the earliest planted sunflowers tended to give the largest yields of fresh matter. Jones, 22 of the Oregon Station, reports a larger tonnage of sun- flowers per acre over a series of years than either oats and vetch or corn grown for silage. McHargue 30 determined the amount of iron in seeds by the col- orimetric thiocyanate method. The amount of iron found in sunflower seeds was .0034 percent, compared to .0039 percent in wheat, .0050 in oats, .0074 percent in soybeans and .0026 percent in yellow corn. The New Hampshire Station 34 reports sunflower yields 40 percent larger than those of corn. Putnam, 37 in time- and rate-of-planting experiments in northern Michigan, found that plantings of May 26 gave larger yields than plantings of June 2 and June 9. "Row y s at distances of 24 to 36 inches gave the best quality of silage." "The 30-42 inch rows gave the heavi- est yields and also required less seed per acre for a stand than did the closer plantings." Quayle 38 found the yield per acre in pounds of sunflowers during 1920 and 1921 to be 50 percent greater than corn. Quesenberry et al, 39 at the New Mexico Station, found that early plantings (April 19) "do not produce as heavy a tonnage or as succu- lent plants as the later seedings." Schafer and Westley 44 report comparative yields of 2.35 tons of dry matter per acre in sunflowers and 1.56 tons in corn at the Washington Experiment Station. Shaw and Wright 46 report the composition of the sunflower plant at seven stages of growth and the corn plant at nine stages. Their results show that when these two plants are compared upon the moisture-free basis, they are similar in total protein and albuminoid protein, but that the mature sunflower plant contains smaller proportions of reducing sugars and non-reducing sugars than the corn plant. The sunflower plant contains very small amounts of starch, whereas the corn plant beyond the "milk stage" contains very large amounts. Yields of the crops are not included. Thatcher 52 compared the yields of dry matter in corn and sun- flowers grown in Ohio for silage. The yields (fresh basis) of sunflow- ers during a three-year period were 14.28 tons per acre, while for corn the yields were 12.78 tons. The yield of dry matter in the sunflowers 7925] THE SUNFLOWER AS A SILAGE CROP 449 was 5,218 pounds, compared to 7,251 pounds in corn. The dry matter of the sunflowers contained greater proportions of protein, ether extract, fiber, and ash than that of the corn, and the yields per acre of the same constituents, with the exception of fiber, were also greater. The greatest difference in composition and yield was with the nitrogen-free extract, which was greater for corn. Vinall 53 says: "The yields of sunflowers have been consistently larger than those of corn or other silage crops in the northern part of the United States and the higher altitudes of the Rocky Mountain region, where the temperatures are low during the summer season." Zavitz 56 reports the annual average yield of Mammoth Russian sunflowers in tests at the Ontario Agricultural College from 1902 to 1920, inclusive, to have been 5.6 tons of heads, 1,453 pounds of ripened seed, and 18.2 tons for the whole crop. CROPS OTHER THAN SUNFLOWER: STUDIES OF COMPOSITION, YIELD, OR FEEDING VALUE, AT DIFFERENT STAGES OF GROWTH Corn Armsby 4 determined the yields and digestibility of corn harvested at different stages of growth during a three-year period. He found in- creases of 200 to 300 percent in the total digestible matter per acre dur- ing the interval from the silking stage to maturity, and increases of as much as 37 percent from the glazing stage to maturity. Yields of total digestible matter in the crop ranged from 4,000 to 6,500 pounds per acre. Armsby, Frear, Caldwell, and Holter 3 found that the coefficients of digestibility of fiber, protein, and true albuminoids in corn fodder were quite constantly depressed as the corn advanced in growth and maturity. Coefficients for fat and nitrogen-free extract, however, in- creased somewhat with maturity. Babcock 6 reported analyses of samples of the maize plant which show increases of 110 percent in percentage of dry substance in the samples of plants taken during the period August 18 to September 23. The dry matter showed decreases in the proportions of ash, crude pro- tein, and crude fiber, but a distinct increase in nitrogen-free extract. Burrill and McCluer 9 reported yields of 6,000 to 9,500 pounds of dry matter per acre in the corn crop. Their studies of the composition of the dry matter of the ears, stalks, and leaves and husk portions of the plant showed that the ears were richest in crude fat, crude protein, nitrogen-free extract, and true protein, but lowest in crude fiber. The leaves and husks were richest in crude ash and poorest in nitrogen-free extract. The stalks were highest in crude fiber, and poorest in crude fat, crude protein, and true protein. Caldwell 10 found yields of 6,000 to 7,500 pounds of dry matter per acre in the mature corn crop, of which the ears comprized from 35 to 450 BULLETIN No. 268 [June, 42 percent. The gains in total dry matter per acre from the fully tas- seled stage to the mature stage were as much as 300 percent. Collier 12 found an increase of about 13 percent in yield of dry matter of the corn plant during the period from September 1 1 to Sep- tember 29, altho total protein was slightly reduced in amount. Farrington 16 followed the composition of the dry matter of the corn plant at weekly intervals from June 17 to September 23. Constant and marked decreases in percentages of ash and protein, together with quite uniform increase of nitrogen-free extract thruout the entire period were noted. There was a slight decrease in the proportion of crude fiber. Frear 17 determined the composition and yields of corn at different stages. The crude protein and crude ash in the mature plants formed about half as large a proportion of the water-free substance as they did in plants three to four feet high. Crude fiber was also somewhat less, while nitrogen-free extract showed an increase. The calculated yields per acre of total digestible organic matter on August 2, August 23, and September 13 (mature stage) were 4,054 pounds, 5,287 pounds, and 8,636 pounds, respectively. Hornberger and Raumer 19 followed the growth of the maize plant from June 18 to September 10. During the period of September 3 to September 10 there was a small decrease in the dry matter, this con- sisting of losses of ash, crude protein, and crude fiber. The starch, sugar, etc., and the crude fat increased during the same period, while the amids declined 30 percent. Ince 20 reported the composition and yield of the maize plant dur- ing the later stages of growth. The dry matter declined in its pro- portions of crude protein and ash, but increased in crude fat and car- bohydrates as the plant approached maturity. The yields from the "glazed" to the "ripe" stage suffered losses of total dry matter, crude protein, and nitrogen-free extract, but made gains in crude fat, crude fiber, and ash. The ash yields, however, were decreased in two of the three cases studied. Jones and Huston 23 determined the composition of maize at several different stages of growth and reported the amount of certain constitu- ents per 10,000 plants. The crop suffered some losses of dry matter, chiefly total ash and nitrogen-free extract, while in the shock from Oc- tober 8 to November 12, but lost more than 20 percent of all constitu- ents except fat while standing in the field during the same period. The greatest loss was in the case of ash, the loss being over 40 percent." Jordan 25 found that the daily rate of gain of dry matter in the corn crop decreased steadily from the time the ears were beginning to form until the ears were glazed. "The datg of Jones and Huston have been used in Figs. 5-24 of the present bulletin in making a comparison of the growth of the corn crop with that of sun- flowers. 1925~\ THE SUNFLOWER AS A SILAGE CROP 451 Jordan, Bartlett, and Merrill 24 noted rapid increases in the nitro- gen-free extract content of the corn crop. Ladd 28 reported increases in the yield per acre of the several con- stituents of the corn crop at different stages of growth. Latshaw and Miller 29 estimated the "weight in pounds of the ele- ments removed per acre from the air and soil by 6,200 Pride of Saline corn plants grown at Manhattan, Kansas, in 1920." The estimated amounts of some of the elements were: nitrogen, 156 pounds; phos- phorus, 22 pounds; potassium, 101 pounds; calcium, 21 pounds; mag- nesium, 19 pounds; sulfur, 17 pounds; iron, 5 pounds; and aluminum, 4 pounds. Morrow and Gardner, 31 from results of field experiments with corn, state that "while there has been a fairly uniform increase in the weight of the ash, protein, fiber, nitrogen-free extract, and the fat or ether ex- tract up to the date when the corn was fairly well matured, the compo- sition of the dry matter shows a steady decrease in the percentage of ash and protein; at first there is an increase and then a decrease in the percentage of fiber; a steady increase in the percentage of nitrogen-free extract, and a good deal of variation in the percentage of ether extract, with, in general, a considerable decrease until the plant becomes nearly mature." Morse 32 observed steady decreases of ash, protein, and fiber, but increases of soluble carbohydrates and fat in the dry matter of corn at different stages of growth. Roberts and Clinton 41 report continuous increases in the yields of all constituents of the corn crop from bloom to maturity. Roberts and Wing 42 report results similar to those of Roberts and Clinton. Schweitzer 45 studied dry matter and ash contents of corn at four- teen successive stages. Dry matter continued to increase in amount in the entire plant, altho there was a decline of dry matter in the stalk during the last periods. The ash of the entire plant decreased slightly during the last period, this decrease being caused entirely by falling off in the stalk, as the ear suffered no losses. Shelton, 47 in studies of the composition of corn at different stages of growth, found that with one exception the fat and nitrogen-free extract increased proportionally as the grain developed, while the fiber, ash, and nitrogenous materials decreased. Short 48 reports losses in fodder corn, due to weathering, of 13 to 23 percent of the dry matter and 60 to 72 percent of the protein. Shutt 49 studied the composition of different varieties of corn dur- ing growth and reported decreases in the proportions of the dry matter made up by ash, protein, and fiber, with increases of "nitrogen-free ex- tract and fluctuations in the ether extract." Smith 50 found increased yields per acre of all constituents of the dry matter from the tasseling to the ripe stage, but the proportions of 452 BULLETIN No. 268 [/