‘RY ' i‘ M CC L l. EG E 0 C A M‘ P S . f; R48-836-6m i EXAS AGRHIULTURAL EXPERMENT $TAT|UN j . ‘ _ A. B. OONNER, DIRECTOR i COLLEGE STATION, BRAZOS-COUNTY, TEXAS ‘ULLETIN N0. 526 SEPTEMBER, 193s DIVISION OF AGRICULTURAL ENGINEERING Calibration 0f Cotton Planting Mechanisms % F fa —-~e 3 ' >7 :3 1* a P; JKGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS T. O. WALTON, President ' HE ..\a:..uQR a. gnaw». a3, Tests were malde with different types of planting mechanisms on cotton planters to determine the number of cottonseed planted per acre and the percentage of seed hulled. Different speeds and adjustments of the planting mechanisms and different sizes of seed were used. ~ Cell-drop planting mechanisms dropped an average of 39,776 cottonseed at low plate speed and 254,724 cottonseed at high plate speed, or 8.61 and 55.16 pounds per acre, respectively. Picker wheel-drop planting mechanisms dropped an average of 33,996 cottonseed at the smallest adjustment and 549,064 when Wide open, or approximately 7.36 and 118.87 pounds per acre, respec- ‘ tively. From 47,596 to 87,043 more medium-sized Truitt cottonseed than large-sized Ducona cottonseed were dropped per acre by cell- drop planting mechanisms with the same plates operated at the same speeds. Picker wheel-drop planting mechanisms dropped from 43,085 to 151,068 more Truitt mediuJn-sized cottonseed than large-sized Ducona cottonseed per acre. The percentage of cottonseed hulled by cell-drop planting mech- anisms ranged from .001 to 1.47 per cent, while the highest per- centage of seed hulled by the picker wheel-drop planting mechan- isms was .46 per cent. At an estimated germination of 70 per cent, cell-drop planters dropped sufficient seed per acre to give an average ranging from 2 to 12 plants per foot. To obtain a perfect stand of one plant to the foot, a minimum of 1 to a maximum of 11 plants per foot would have to be thinned out. The number for picker wheel- drop planting mechanisms ranged from a minimum of 2 to a maxi- mum of 27 plants per foot, requiring the removal of from 1 to 26 plants per foot to leave one plant per foot. é78zq CONTENTS Introduction History of cotton planter development Cottonseed planting mechanisms Requirements of planting mechanisms Method of calibrating cotton planters Equipment and procedure Experimental results Cell-drop planting mechanisms- Picker-wheel planting mechanisms Hill-drop planting mechanisms Summary and conclusions 10 13 15 17 17 24 31 32 ' ‘ ‘YJXZWWW BULLETIN NO. 526 SEPTEMBER, 1936 TCALIBRATION OF COTTON PLANTING MECHANISMS H. P. Smith, Chief, and M. H. Byrom, Asst. Agricultural Engineer, Division of Agricultural Engineering. The selection of a cotton planter equipped with a planting mechanism that will drop the desired quantity of cottonseed and distribute them uniformly in the seed furrow is often a problem. The individual has no way of knowing in advance the quantity of seed a cotton planter will distribute per acre. The manufacturer does not put a seeding rate gauge on the planter because cottonseed of difierent varieties vary in size and the planter will not drop a uniform quantity of seed per acre of each variety. For this reason the individual who desires to know with some degree of accuracy the quantity of seed the planter will dis- tribute per acre should calibrate it each year with some of the‘ seed he intends to plant. ’ The cotton planter equipped with the cell-drop type of mechanism is usually provided with three plates, and when any plate is used, it can be operated at three difierent speeds. This range of speeds and this number of plates permit the selection of nine different rates of seed distribution, which should be sufficient to meet the requirements of most field conditions. Planters equipped with the picker-wheel type of planting mechanism permit a choice of a wide range of seed distribution rates. The slightest movement of the shutter will vary the size of the opening through which the picker wheel picks the seed from the hopper and will give a different seeding rate per acre. Because of the different types of planting mechanism on the various cotton planters on the market and because of the fact that the seed of different varieties of cotton vary greatly in size, it was considered desir- able to conduct tests to determine the amount of seed that may be planted with different types of machines when seed of various sizes are used. The results reported in this bulletin cannot be taken as the actual quantity of seed of all varieties of cotton the planters tested will dis- tribute. The data should, however, enable the individual user to have some idea as to the number of seed and the quantity of seed that will be planted per acre and the adaptability of the different types of planting mechanisms to the planting requirements on his farm. HISTORY OF COTTON PLANTER DEVELOPMENT Primitive Cotton Planters: The first attempt to improve upon the hand method of planting cotton was made by filling a cow horn full of seed and scattering them along the furrows. Other early and ingenious 6 BULLETIN NO. 526, TEXAS AGEFCULTURAL EXPERIMENT STATION arrangements consisted of barrels or kegs with holes bored at intervals around the middle through which the seed dropped as the barrel or keg rolled along the furrow. " Figure 1. Dow Law Cotton Planter. First Improved Cotton Planters: The first great forward step in cotton planters was the invention of the Dow-Law Planter about 1870. This planter (Fig. 1) included a trapezoidal hopper mounted upon a wooden frame, at the front end of which was a steel furrow opener blade. The Figure 2. Carolina Cotton Planter. CALIBRATION OF COTTON lr¢ANTING MECHANISMS 7 drive wheel was located between the opener and hopper. This wheel, about two inches wide, was made of wood;\ it rolled in the furrow behind the furrow opener, pressing the loose soil, upon which the seed were dropped, into a firm seed bed. In the center and at the bottom of the hopper was an adjustable feed-gate, which could be regulated to give any Figure 3. One-row walking mule-drawn cotton planter. Figure 4. One-row riding mule-drawn cotton planter. 8 BULLETIN NO. 526, TEXAS AGRICULTURAL EXPERIMENT STATION desired flow of seed. The seed were covered by a drag-board attached to two springs suspended from the rear of the frame. A slight improvement over the Dow-Law Planter was known as the Carolina Cotton Planter (Fig. 2). The main difference between the two was the method of driving the seed agitator. In the Dow-Law Planter the agitator was driven by a pitman, while the Carolina Planter used a chain running over sprockets, which caused the agitator to work with a rotary instead of a reciprocating motion. Modern Cotton Planters: With the development of cottonseed by- products, such as cottonseed oil, meal, and hulls, cottonseed becamea o Figure 5. ~TWO-I‘OW riding mule-drawn cotton planter. Figure 6. Four-row tractor cotton planter. CALIBRATION OF COTTON PLANTING MECHANISMS 9 valuable marketable commodity instead of an encumbrance about farms and gins. Hence, inventors studied economy in seed planting. € ; beginning somewhere in the 80's, the principle used in corn was adopted and force-feed cotton planting mechanisms were de- Since 1900 cell-drop and picker-wheel planting mechanisms, enable the cotton farmer to plant almost any quantity of seed conditions require, have been designed. Some mechanisms, how- , will plant more seed per acre than others. Hill-drop attachments are of recent origin, having been developed within the past ten years. cell-drop or picker-wheel drop planting mechanisms and hill-drop ents can be obtained on all types of planters, including the one- walking (Fig. 3), the one-row riding, mule drawn (Fig. 4), the IQ‘ ' w \ ‘ “ . . a , / A n I I : v1.1 uuuuuuuu :1 e n u < n 1 11 0 v Y Y 0 n K I " . L. nnnnn LL " A n I 1.1 I A u n : n» I ~ ~ n C Y U V A L II Lfistun One Row Walking N One Row Rldmg Two Row Rulmg fiTwo, Three, and Pour Row Tractor C] Lattle Cotton Grown or no lnformquorw Avanlable. 2 -,l,. 1 K~_N£9V 7.3 Map of Texas showing areas {different types of cotton planters lfgzinate. nnnn ull 10 BULLETIN NO. 526, TEXAS AGRICULTURAL EXPERIMENT STATION two-row riding, mule drawn (Fig. 5), and the four-row tractor mounted (Fig. 6). It appears that the type of planter used is influenced by soil type, type of farming, and climatic conditions, as there are definite areas in the state of Texas where difierent types of planters predominate. Figure 7 shows the areas where each type of planter is most used. COTTONSEED PLANTING MECHANISMS Good cultural practice and good seed may be of little consequence unless the seed are placed in the ground in such a way that a good stand of plants will be obtained. Therefore, the dropping mechanism on the modern planter is important. The method of- getting the cottonseed from the hopper into the seed tube and thence into the soil determines the type of drop used on the plan-ter. There are two types in common use, the cell or single seed drop and the picker-wheel drop, which is sometimes called the reverse feed type of drop. Hill-dropping attach- ments can be used with either type of dropping mechanism. ' Cell-Drop Mechanism: The cell or single seed dropping mechanism consists of a metal plate about 8 or 9 inches in diameter, around the outer edges of which are holes called cells (Fig. 8). The shape of the cells varies according to the ideas of designers. Cells in the plates used Table 1. Characteristics of seed plates of cell type dropping devices for cotton planters. Cell Ratio of plate travel to _ planter wheel travel Planter Platew Plate Thlckness (Plate Speed) Number Number Diameter of plate Number Capacity ._._ in inches per Shape Average plate size seed Low Medium High 1 1832 8% thick 25 U 2" 8 1.33 1 71 1 1754 " medium 25 U 2 to 3 . . . . . . . . . . . . . . . . . . . . . . . . 1 1768 " " 2S U 3 t0_4 . . . . . . . . . . . . . . . . . . . . . . . . 2 378A 8% medium 2O U 2 1 23 1.38 1 60 2 7980A " thick 32 U 3 . . . . . . . . . . . . . . . . . . . . . . . . 2 7942A "' thin 4O U 3 . . . . . . . . . . . . . . . . . . . . . . . . 3 M-17 9% thin 52 U 1 71 1.08 1 4 3 M-17A " medium 50 U 2 . . . . . . . . . . . . . . . . . . . . . . . . 3 *M-17B " thick 15 U 1 . . . . . . . . . . . . . . . . . . . . . . . . 4 G391A i 9% thick Ellip- 3 4 G596 " " tical 2 4 G393 " " " 3 4 G576 .. .. .. 4 4 II II I! 4 4 n n n 3 ‘Hill-drop plate. in this study were. either elliptical or U-shaped (Table 1). Most planters are regularly equipped with three plates, but special plates may be ob- tained. The cells differ in size and number. The plates, also may be of PR£$$£3FE - swarm:- CALIBRATION OF COTTON PLANTING MECHANISMS 11 mcw-caaezama cur-raw;- HVER"? CIETLL Ffilmiffifi ' saw PLATE fiiiiTfiTfifi ifiifififiilfifi scams Figure 8. mechanism for planting cotton. A typical cell-drop planting different thickness (Figs. 15, 17, 18, and (19). This variation in number and size of cells a.nd thickness of plate makes it possible to plant cottonseed at dif- ferent rates and to handle seed of different sizes. Pro- vision is made on most cell- drop planters for operating the plate at three speeds, thus changing the seeding rate without changing the plate. Table 1 shows the ratio of plate travel to the planter wheel travel for four planters. To get cottonseed into each cell as the plate ro- tates, feed springs are at- tached to projections inside the hopper just above the cells. As the plate turns, an agitator stirs and sepa- rates the seed, causing them to work down under the feed springs, which gently press one or more seed into each cell (Fig. 8). Just before a cell reaches the point above the seed tube, a yielding cut-off slips under and separates all sur- plus seed that may be resting on the sections of the plate between the cells and on the seed in the cells. As the cells pass over the seed tube, a knockout under spring pres- sure partially drops into each of them (Fig. 8) forcing the seed downward through the cells into the seed tube, through which they fall into the seed furrow. Some cell-drop planters use a rigid cut-off, which sets at Figure 9. Cell-drop planting mechanism with plate mounted eccentrically with the hopper. (Note the spur wheel knockout.) 12 - BULLETIN NO. 526, TEXAS AGRICULTURAL EXPERIMENT STATION an angle across the cells to push back the surplus seed. These planters also use spur-like wheel knockouts, the prongs of which extend down into the cells, punching the seed out through the plate into the seed tube (Fig. 9 and 10b). Picker Wheel Mechanism: This type of dropping mechanism uses a horizontal rotating agitator plate with radial fins or fingers and a picker wheel, located under the fingers on the rear side over the seed tube. The picker wheel is set at right angles to the radial fingers and rotates in the opposite direction against them. For this reason, it is sometimes termed a reverse feed. There are three distinct types of picker wheels used in Figure 10. Cell-drop and picker-wheel drop planting mechanisms used on planters Nos. 4 and 7. A. Picker-Wheel drop. B. Cell-drop with spur Wheel knockout. I this dropping mechanism, the narrow wheel With recessed teeth (Fig. 11), the wide wheel with uniformly spaced teeth (Fig. 10a), and the wide a wheel with staggered teeth (Table 2). The quantity of seed discharged by the dropping mechan- ism is regulated by a shutter, which may or mary not cover the wheel. As the shutter is opened, increas- ing the open area about the picker wheel, more seed are dropped. Table 2 shows the size of shutter openings used in three planters. In operation, one or two stirring arms (fastened to and extending up- ward from the agitator plate) .keep Figure 11- Picker-Wheel d?” used the seed loose and in contact with on planter No. 6. A ~ CALIBRATION OF COTTON PLANTING MECHANISMS 13 he fingers, which press the seed downward on the picker wheel that in turn picks them out of the hopper and feeds them into the seed tube. Table 2. Characteristics of picker-wheel dropping devices for cotton planters. Ratio of Shutter Diameter Width picker- Picker- of picker of No. Height wheel Planter Wheel wheel rim of o to " Distance ‘ Type in in teeth teeth planter Length Width above . inches pinches wheel in in or below travel inches inches wheel 6 narrow. . . 3% pg 12 M" 5 . 2S 2% % - %" 7 wide... . . 3%} i-Z- 18 M" 3.33 2% 1 4" 8 narrow. . . 311g f’; 14 )4" 3.92 2% 1 I/é" ; Hill-Drop Mechanism: The earliest hill-drop mechanisms consisted of cells spaced at suitable intervals in the planter plate and large enough ;(to hold suflicient seed for one hill (Fig. 18), or of picker wheels with 4e notches cut in their surfaces so spaced as to drop the seed in hills (Fig. i 12). These hill drops were located in the bottom of the planter hopper, Qjand it was necessary for the seed for each _ 1155 "a hill to fall from the hopper through the seed tube to the soil. In falling a distance of some 18 or 20 inches the seed became sepa.- _ rated and scattered along the furrow to such an extent that it was difficult to distinguish _» one hill from another. Later someone con ceived the idea of placing a valve in the, lower part of the seed boot close enough to the ground to prevent the seed from scatter- ‘ ing when they were dropped (Fig. 13) 7 Walking and riding horsedrawn planters and i, tractor planters equipped with hill-drop - - Figure 12. Regular and hill- mechamsms are now avallable. Horsedrawn drop Dicker Wheels used on planters are equipped with a trip valve in the planter N0. 7. boot, while tractor planters are equipped with a rotary valve type of _ hill drop. The trip valve type will not withstand the strain of the higher speeds attained by tractors. ~ REQUIREMENTS OF PLANTING MECHANISMS Most planting seed are used as they come from the gin. More or less lint is left adhering to them. Small sticks, leaf trash, and bur sections are also found among the seed. The amount of lint and trash present will greatly influence the rate at which seed will be dropped and the frequency with which the hopper will have to be cleaned. The size of the seed is also an important factor. The picker-wheel drop is less afiected by trash and lint than the cell drop. The picker-wheel tends to pick the trash out along with the seed, while in the cell drop trash may accumulate "to such an extent as to keep some of the cells from being properly filled. 14 BULLETIN NO. 526, TEXAS AGRICULTURAL EXPERIMENT STATION N; l. F1 ~ SAW "room 0 PICKER WHEEL Q /MAIN_ AXLE mm / MAIN FRAME SIDE BAR/ Cj/ // a a seen SPOUT-——> ' 1;" ARM . l ~// 1/ BOOT “I / 1/ ) omvs GEAR TRwARM SHAFT ' é? omvzu cam /. t" ’ ¢°"";§g'"° sperm-sermon cm 4 POINT- I4" DROP CAM BRACKE; 5 POINT- W020? cm -'- on e00 .,/ , SPRING CRANKARM TO TRIP VALVE Q ° _ <—-—ADJUSTABLE VALVE ROD wrrn SWIVEL DOUBLE LIP VALVE LOWER LIP CLOSED, ACCUMULATING SEED. UPPER LIP OPEN RUNNER HILL OF SEED IN FQRROW? Figure 13. seed boot. Cutaway View of hill-drop installed in‘ Quantity of Seed Required: The na- ture of the cotton- seed, the type of soil in which they are to be planted, and climatic condi- tions largely deter- mine the quantity of seed planted. A recent survey re- vealed that from ten t0 fifty pounds of seed per acre are planted in the cot- ton growing areas of Texas. From sixteen to thirty pounds is generally used, while twenty- one pounds is the average for the state. Tests reported in this bulletin were undertaken to de- termine to what ex- tent the various planters on the market would meet the requirements of the cotton growers of Texas. Number of Plants Per Acre: It has been found that cotton plants spaced twelve inches apart give the best yields under most conditions in Texas. * This would require 14,520 plants per acre, when the rows are three feet apart, or 12,408 when they are three and one-half feet apart (Table 3). From three to five pounds of seed would be suflicient to produce the required number of plants, provided they were properly distributed and germinated 100 per cent. _ Table 3. Number of plants per acre with diflferent row and hill spacing. One Plant to Every Width of row in feet _ _ _ 4 inches 8 inches 12 inches 16 niches 20 inches 24 inches . l 3 43,560 21,780 14,520 10,890 8,712 7,260 3% 37,338 18,669 12.446 9,334 7,468 6,223 4 32,670 16,335 10,890 8,168 6,534 5,526 . 4% 29,670 14,825 \ 9,213 7,417 5,934 4,945 5 26,136 13,068 8,712 6,534 5,227 4,356 | - 3"‘ Texas Agricultural Experiment Station Bulletins No. 340 and No. 360. CALIBRATION OF COTTON PLANTING MECHANISMS l5 The young cotton plant, however, is very susceptible to disease and insect injury, and frequently plants die in large numbers. This and the fact that not more than an average of 70 per cent of the cottonseed planted will germinate make it necessary to distribute a much larger quantity of seed than the number of plants required. METHOD OF CALIBRATING COTTON PLANTERS To calibrate or test a cotton planter t0 determine the quantity of seed of a certain variety of cotton that will be planted per acre with a par- ticular plate or setting, the following directions should be observed: (1) Determine the width in feet between rows. (2) Divide 43,560 (the number of square feet in an acre) by the width between rows. The result will be the distance the planter must travel to plant one acre. (3) Find the circumference of the planter wheel in feet. Divide the distance to be traveled in planting an acre by the circumference of the wheel. This will give the number of revolutions the wheel must make to plant an acre. Wheel slipage is not considered. (4) Fill the seed box with cottonseed and place a box under the seed spout. (5) Jack up one of the wheels. Tie a rag around one of the spokes so the revolutions can be counted. (6) Engage the clutch and turn the wheels, counting each revolu- tion. Turn at about the speed the planter will travel in the field. To determine the quantity that will be planted per acre, when" the wheel has been turned the equivalent of .1; to é an acre, weigh the cottonseed that have been dropped and multiply the amount by 4 if é acre was selected, or by 2 if % acre was sown. At least three trials should be made and the results averaged. EQUIPMENT AND PROCEDURE Methods of Making Tests: Truitt seed were used in five tests for each‘ plate andspeed combination possible with the cell-drop planters, and in five tests at each of four settings of the shutter (that is, one-fourth open, one-half open, three-fourths open, and wide open) with the picker-wheel drop. All tests were for the equivalent of one-fourth acre with the rows spaced three feet apart. The results of the five tests were totaled and averaged and the result multiplied by four to obtain the quantity dropped per acre. Similarly, three tests were run in each of the planter combina- tions with Ducona seed. 1c BULLETIN NO“. 52s; TEXAS-AGRICULTURAL EXPERIMENT STATION The seed were thrown from the seed belt into a box, after which they were‘ weighed- To determine‘ the percentage of injury caused by the planting mechanism of each p-lanter tested, all seed of each test made with Truitt seed were screenedlto remove the seeds that were hulled. The hulled seed were counted ‘and the percentage of injury calculated. The percentage of injury to Ducona seed wasnot determined. Equipment Used in Tests: The one-row riding type planter was selected for calibrating the dropping mechanism because it could be readily mounted on a stand and operated by means of an electric motor and belts, the arrangement of which is shown in Figure 14. A belt six inches Figure 14. Stand used in testing cotton planters with planter mounted on stand. wide and six feet long was mounted in an auxiliary frame attached to the stand in such a way that the seed passing through the planter would drop upon it as they normally drop in the seed furrow. The planter wheel was belted to the motor so that it would turn an equivalent of two and one-half miles an hour. The seed belt moved un- der the seed tube at the same speed. A revolution counter was mounted on the end of the planter axle to count the revolutions of the planter wheel so that each planter could be tested for the same equivalent part of an. acre. . Several typical commercial one-row riding planters were selected for testing; some of these could be converted from the cell-drop to the picker- wheel drop by changing the hopper mechanism. ' - As a general rule, cell-drop planters are made so that the plate can be operated at three speeds termed low, medium, and high. The picker- wheel drop can be operated at one speed only. :.CALIiBRA-TION QOF‘ COTTON PLANTING MECHANISMS 17 Kinds of Cottonseed Used: As the size of seed varies for difierent varieties of cotton, the Truitt and Ducona varieties were selected to test. The Truit-t has representative small seed averaging 4,619 seed to the pound. _ The Ducona’ isfa fair representative of the large seed varieties, averaging about 3,780 seed to the pound. The seed were used as they came from the gin; that is, they were not delinted, recleaned, or graded. EXPERIMENTAL RESULTS Cell-Drop Planting Mechanisms Planting Mechanism Number 1 The complete dropping mechanism of -this planter with all accessories is shown in Figure 8. The seed plate has the seed cells on the outer edge; these cells are U-shaped (Table 1). A sloping by-pass permits seed that cling to the plate to pass back into the hopper. Two fiat stirring armskeep the seed agitated and fed down under the feed springs into the seed cells. __ ' Results with Truitt Seed: Table 4 shows the actual number of seed dropped per acre, the equivalent in pounds, and the percentage of seed hulled, while Table 5 shows the number of seed dropped in relation to the number of plants obtained when 70 per, cent of the dropped seed germinate. Table 4 shows that plate No. 1832 (Figure 15) dropped 63,916 Truitt \ a seed at low speed, while plate No. 1768 (Figure 15) dropped 254,724. Figure 15. Plates tested with planter No. 1. seed at high speed. The equivalent in pounds was 13.84 for plate No. 1832 and 55.16 for plate No. 1768. The percentage of seed hulled ranged from .59 per cent at low speed to 1.47 per cent at high speed for plate No. 1832. Figure 16 shows the regularity with which this planter dropped the seed. It will be noted that while there was a tendency to bunch the seed to some extent, this was not enough to be an objectionable feature. 18 BULLETIN NO. 526, TEXAS AGRICULTURAL EXPERIMENT STATION I r ti‘ i? i i! . I’ Figure 16. How seed were distributed by plate N0. 1768 on planter No. 1 at 10W, medium, and high speeds. Q The number of plants per foot at 70 per cent germination ranged from 3.08 to 12.28. In other Words, for every plant left approximately two will have to be removed per foot when the planter is set -to drop the minimum amount of seed, and approximately 11 plants will have to be removed per foot for each one left when the maximum amount of seed are dropped. This gives a rather wide range in the quantity of seed that can be distributed and should make the planter adaptable for use under most conditions. Results with Ducona Seed: The tests on planter No. 1 with Ducona seed revealed that the larger seed could be handled by the dropping mechanism as readily and efliciently as the smaller Truitt seed. A lar- ger quantity of the Truitt seed was dropped in every test. Plate No. 1832 at low speed dropped 4.52 pounds of seed per acre more Truitt than Ducona (Table 4). With each plate and at each speed the quantity gradu- ally increased until with plate No. 1768 at high speed 10.80 pounds more Truitt seed were dropped. The number of plants removed per foo-t for each plant left ranged from less than one for plate No. 1832 at low speed to 7.08 for plate No. 1768 at high speed (Table 5). 19 .325 596-25 u. CALIBRATION OF COTTON PLANTING MECHANISMS . 32S 232 8.2 @812: .. . 3.2 818 00. Rm ww.w ~00. 80 oww. m2 2.0 02m 00 20. 3 . . . .00_:w0M w 00 .00 8.... w?» 000. 8w .3 . 00 02. 000 ww0. 0.8 3 .0 Sm. 0w m8. 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The number of plants thinned out for each plant left, 12 inches apart in the row, ranged from 1.74 for the one-fourth shutter opening to 18.19 at full opening. The number and percentage of hulled seed were not obtained for Ducona seed. Figure 22. _HoW picker Wheel shown in Figure 10A and used on planter N0. 7 distributed cottonseed at the different settings of the shutter. The seed were dropped regularly at all shutter openings (Fig. 22). Very few blank spaces were noted on the seed belt. The uniformity of drop was probably due to the wide picker Wheel, which permitted no seed to get out of the hopper except those picked out by the picker-wheel teeth. Planting Mechanism Number 8 \ This dropping device was equipped with a narrow picker Wheel similar to that used by planter No. 6 (Fig. 11).‘ The seed control shutter opened CALIBRATION OF COTTON PLANTING MECHANISMS 31 slightly wider, and the picker wheel did not project as far into the’ hopper. This planter was tested only with Ducona seed. Table 6 shows that the number of Ducona seed dropped at each of the settings was slightly greater than for planter No. 6, and that the plant ratios were correspondingly greater (Table 7). The number of seed dropped ranged from 97,675 for the one-fourth shutter opening to 461,311 for the full opening, or 25.84 and 122.04 pounds, respectively. The small one-fourth shutter opening permitted almost a bushel of seed to be dropped, while the maximum was about four bushels per acre. At 70 per cent germination the number of plants ranged from 4.71 per foot for the one-fourth setting to 22.24 per foot at the wide open setting, requiring the removal of from 3.71 to 21.24 plants per foot to leave one plant per foot. HILL DROPPING At the time these tests were made no hill-drop attachments for the seed boot were available. Tests were made with three picker-wheel drops and one plate hill drop. Results for the hill-drop plate No. 17B for planter No. 3 are shown in Table 4. The table shows that consider- ably less seed were dropped with the hill-drop plate than with the regu- lar plates Nos. 17 and 17A. The tests indicated that when the hills were formed by the planting mechanism, the seed separated in dropping and scattered on the belt until it was hard to distinguish the hills. Exper- ience in the field has proved that this type of hill drop is not satisfactory. All planters are now equipped with a valve in the seed boot near the ground. . The hill-dropping mechanism is placed in the boot of the seed tube, and the regular planting mechanism is used to extract and drop the seed from the seed hopper. The number of seed per hill is varied in cell-drop planters by three methods: (1) by running the seed plate slower or faster, (2) by changing the plate to drop a different number of seed, and (3) by varying the speed at which the valve operates. The rate at which the valve opens and closes also determines the spacing of the hills. The number of seed dropped per hill can be obtained from Table 3, which shows the number of hills per acre for different row and hill spacings. For example, if the rows are spaced 3 feet apart and the hills are to be spaced 12 inches apart, there will be 14,520 hills to the acre. If the planter is dropping 94,348 seed to the acre (Table 4, planter No. 1, plate No. 1832 at medium speed), by dividing the number of seed the planter drops per acre by the number of hills desired per acre, the number of seed per hill is obtained; in this case 94,348 divided by 14,520 gives 6.50, or approximately 7 seed to the hill. If 70 per cent of these seed germinate, approximately 5 plants per hill may be expected (Table 5). 32y BULLETIN NO. 526, TEXAS AGRICULTURAL EXPERIMENT STATION sUMnfARY AND CONCLUSIONS Tests were made on cell-drop and picker-wheel drop cotton planting mechanisms to determine the quantity of cottonseed planted perxacre and the percentage of seed hulled in passing through the difierent types of planting mechanisms. The smallest number of cottonseed dropped per acre by the cell-drop planting mechanisms tested was 39,776 at low plate speed, while the largest number was 254,724 seed at high plate speed. This is equivalent -to 8.61 and 55.16 pounds, or approximately i‘; and 12 bushels per acre. Picker-wheel drop planting mechanisms had a wider spread than the cell-drop planting mechanisms between the minimum and maximum quantities of seed dropped, ranging from 33,996 to 549,064 seed per acre. The equivalent in pounds is 7.36 and 118.87, or approximately i and 3% bushels per acre. The size of the seed materially influenced the quantity of seed dropped. When the same plates and speeds were used to drop medium-sized Truitt cottonseed, from 47,569 to 87,043 more seed were planted per acre than with the larger-sized Ducona seed. Seed dropped by picker- wheel drop mechanisms ranged from 43,085 to 151,068 more medium- sized Truitt seed than large Ducona seed per acre. The percentage of seed hulled by cell-drop planting mechanisms ranged from .001 per cent to 1.47 per cent. The highest percentage of seed hulled by picker-wheel drop planting mechanisms was .46 per cent. If 70'per cent of the smallest and largest number of seed dropped by cell-drop planting mechanisms germinated, the number of plants ob- tained would range from approximately 2 to 12 per foot. To obtain a perfect stand of 14,520 plants per acre, from 1 to 11 plants per foot would have to be thinned out. The number of plants per foot for picker- wheel drop mechanisms ranged from 2 to 27, requiring the removal of from 1 to 26 plants per foot to leave one plant per foot.