Energy Consumption and Yields for Cotton Tillage Systems

Transcription

1 Energy Consumption and Yields for Cotton Tillage Systems Item Type text; Article Authors Rein, B. K.; Thacker, G. W.; Coates, W. E. Publisher College of Agriculture, University of Arizona (Tucson, AZ) Journal Cotton: A College of Agriculture Report Download date 08/07/ :36:01 Link to Item

2 Energy Consumption and Yields for Cotton Tillage Systems B. K Rein, G. W. Thacker, W. E. Coates ABSI1tACr The energy consumption of 2 alternative tillage systems for continuous cotton production in Arizona were compared to a conventional system. The tests were conducted at the University of Arizona Marana Agricultural Center. Results of the study in a Pima I clay loam soil showed the sundance treatment to have the lowest energy requirement of 39 Hp -hr /ac (73 kw- h/ha); the USM system had the second highest of 58 Hp -hr /ac (107 kw- h/ha). The conventional system required 67 Hp -hr /ac (124 kw- h/ha). Average yields for all 3 systems were not significantly different. A continuation of this study will be conducted to determine long -term effects on energy consumption, yields, and soil compaction. INTRODUCTION The principal functions of the primary tillage operations in a continuous cotton cropping system in Arizona are: 1.) to uproot the cotton stalks preventing the regrowth of the stub cotton that provides a host for the bollworm to reproduce on, and 2.) to reduce the density of the soil and to construct or form the seedbeds. The desert soils of Arizona have certain characteristics that must be considered when planning tillage operations. They are easily compacted if worked too wet and will turn up clods that are difficult to break down if plowed or chiseled when too dry. Conventional tillage practices for a continuous cotton cropping system in Arizona typically includes shred stalks, disk, subsoil or plow, disk, disk, float, and list. More than half the fuel required for machinery operations in producing a crop of cotton in Arizona is used before the plants emerge (Cannon et. al, 1977). Previous research on cotton production in Arizona evaluated the use of a chisel -lister for minimum tillage (Cannon, 1975). Results of that research showed a savings of almost 75% of the fuel and labor inputs used in a continuous cotton cropping system. The primary drawback was that the chisel -list systems created very rough seedbeds that made planting extremely difficult. A 10 -year study in Texas showed that tillage required only to reconstruct the elevated seedbed between each growing season produced yields of cotton comparable to conventional systems (Wilkes, et al 1979). However, merely reconstructing the beds will not satisfy Arizona requirements for controlling bollworms. In the past 3 years new cotton tillage machinery has been introduced in Arizona that reduces the number of tillage operations and satisfies Arizona plowdown requirements. It is important to Arizona cotton producers that any changes in cultural practices not result in yield reductions and that any reduction in cotton tillage costs be verified. 39

3 OBJECTIVES The objective of the research reported here was to compare the energy consumption and yields of 2 reduced tillage systems for continuous cropping to a conventional tillage system. Tillage Systems The following describes the first year's sequence of operations after picking through seeding for each production system. Conventional System 1.) Shred stalks with a 4-row flail shredder. 2.) Level the beds by disking parallel to the rows with a 13.5 foot offset disk. 3.) Subsoil with parabolic shanks spaced 27 inches apart at a depth of inches on a diagonal direction. 4.) Disk across the other diagonal with same disk. 5.) Apply herbicide and lightly incorporate it with the disk. 6.) List to form beds with 14 -inch listers spaced 40 nches apart. 7.) Pre -irrigate 8.) Mulch beds with a rotary tiller for planting. 9.) Plant Uprooter- Shredder -Mulcher (USM) System 1.) Uproot, shred, and bury the stalks in the furrow with the USM. 2.) Subsoil and reshape the beds with a 4 -row chisel- lister. Subsoil in the bed inches deep. 3.) Shape the beds with a 6 -row bed shaper for banding herbicide. 4.) Pre -irrigate 5.) Mulch beds with rotary tiller to incorporate herbicide and prepare beds for planting. 6.) Plant The USM, developed by S. Ben -Dor, Automotive Industries Ltd., is the principal implement used in this system. It was designed to maintain the same beds and furrows each season. It is a 2 -row implement with sweeps that cut the cotton plant root approximately 6 inches below the surface. A pair of PTO driven counter -rotating rubber wheels grab each row of stalks just above the soil line and extract the stalk and taproot from the soil. A set of belts feeds the stalks into a shear -bar chopper. The chopped stalks are discharged down a chute behind a furrow opener. Soil falling back into the furrow covers the chopped stalks. Sundance System 1.) Shred stalks with 4 -row flail shredder. 2.) Uproot stalks with Sundance uprooter. 3.) Shred stalks again to reduce size of tap root and remove lower nodule. 4.) Subsoil and reshape the beds with a 4 -row chisel -lister. Chisel in the bed inches. 5.) Shape the beds with a 6 -row bed shaper for banding herbicide. 6.) Pre -irrigate 7.) Mulch beds with a rotary tiller to incorporate herbicide and prepare beds for planting. 8.) Plant Sundance Farms of Coolidge, Arizona, designed their system for growing cotton using subsurface trickle irrigation. Since subsurface trickle laterals are left in place for several years, the beds and furrows must be maintained from season to season. The unique implement developed for their system is an uprooter that pulls the stalk loose with 2 converging disks. The edges of the disks are forced 1-2 inches into the ground and rotated by contact with the ground and flanges welded to the outside of each disk. The convergence of the lower portions of the disks, toward the rear, causes the root to be gripped and lifted. Shredding the stalks close to the 40

4 ground following the operation reduces the amount of unshredded root remaining and removes the bottom nodule. Killing the tap root in that manner guarantees that stub cotton will not regrow in the early spring. Experimental Design and Procedure: The test plots were located on the University of Arizona's Marana Agricultural Center. The soil type is a Pima I clay loam with mechanical analysis of approximately 28% sand, 40% silt, and 32% clay (Post et al, 1978). The surface layer ranges from inches deep, averaging approximately 24 inches. The 3 systems were set up in a randomized design with 4 replications of each system for a total of 12 plots. The plots were comprised of 12 rows, spaced 40 inches on center, each 565 feet long. The conventional system plots also had 8 border rows on each side to accommodate equipment turn around for diagonal operations. All data used to evaluate the field operations were obtained from the center 4 rows of the plots. Four -row equipment was used for all operations with the exception of the USM implement (2 -row) and the bed shaper (6 -row). Wheel traffic was restricted to every other furrow in the USM and Sundance Systems. The parameters measured were implement draft, travel speed, and PTO torque and speed if required. Travel speed was measured by means of a wheel driven from a front tractor tire. A magnetic pick -up sensed the rotation of a toothed sprocket fixed to the wheel. Drawbar draft was measured with a 50,000 lb load cell while draft for 3 -point hitch mounted implements was measured with strain -gage bridges cemented to an intermediate three -point hitch assembly. PTO torque was measured with an 833 foot /pound torque transducer. A magnetic pick -up measured PTO speed off a sprocket that was part of the torque transducer. Measurements were taken at 0.2 second intervals for those implements with no PTO power requirement and 0.5 second intervals for those implements using PTO power. All transducer outputs were input to a Campbell Scientific 21x data logger and down loaded to magnetic tape. Data was transferred from tape to ASCII comma delineated files and analyzed using a Quattro spreadsheet software program. RESULTS AND DISCUSSION The following results are from the first year of a 3 -year study that will compare energy and power consumption, soil compaction, and yields for the 3 tillage systems. Overall the energy data was fairly consistent. The highest coefficient of variation of 36 was found for the stalk shredding and is not unusual for that type of operation. The coefficient of variation for the other operations varied from 5 to 15. Results of the mean energy consumption for each operation for the conventional, sundance, and USM systems are shown in figures 1 through 3 respectively. Subsoiling required the most energy for the conventional and sundance systems although the USM required the most energy for the USM system. Energy consumption for subsoiling the conventional system was higher than the other 2 systems due to the closer shank spacing, 27 inches vs. 40 inches. The USM implement had the highest energy consumption for any individual operation. Approximately 72% of its energy consumption was for draft and 28% of the energy was consumed for the PTO. Shredding stalks and mulching were primarily PTO loads with very small draft loads. The energy for mulching the conventional system was substantially less than the energy to mulch the other 2 systems since the soil had been worked more for the conventional system. The total energy consumption for each system are shown in figure 4. The conventional system had the highest total energy consumption of 67 Hp -hr /ac (124 kw- h /ha). The USM system had the second highest with 58 Hphr/ac (107 kw -h /ha) and the sundance system had the lowest energy consumption of 39 Hp -hr \ac (73 kwh/ha) even though the sundance system had 2 more operations than the USM system. That was primarily due to the minimal amount of soil disturbance in uprooting the stalks. It is important to note that the field was not floated as is often done in conventional tillage, which would have resulted in an even higherenergy consumption for the conventional system. Yields were determined by harvesting the center 4 rows of each plot with a 4 -row cotton picker, dumping to a wagon, and weighing the seed cotton yield with a set of portable scales. Yields from the first year's data were low for all 3 systems due to herbicide damage resulting from an application of herbicide at layby. Average lint yields for the conventional, USM, and sundance systems were 782 pounds /acre, 735 pounds /acre and

5 pounds /acre respectively. Yields were not significantly different at the 0.05 level by the Student -Newman- Kcul's Test. Trade or brand names are used only for the purpose of educational information. The information herein is supplied with the understanding that no discrimination is intended and no endorsement by the University of Arizona is implied. REFERENCES 1. Cannon, M. D., Stapleton, H. N Minimum Energy Tillage Systems. Technical Bulletin No Univ. of Arizona, College of Agriculture. 2. Cannon, M.D Minimum Energy Tillage Concepts in Arizona. ASAE Technical Paper no Am. Soc. Agric. Engineers, St. Joseph, MI. 3. Wilkes, L.H Minimum Tillage for Cotton. ASAE Technical Paper no Am. Soc. Agric. Engineers. St. Joseph, MI. 4. Post, D.F., D.M. Hendricks, and O.J. Perei Soils of the University of Arizona Experiment Station: Marana. Agric. Engineering and Soil Science, Univ. of Arizona, No

6 CONVENTIONAL SYSTEM OPERATION Shred stalks i Disk 1 Subsoil Disk 2 iiiiiiiiiiiiiiiiii.. P., !.!.!.!.!.1.:.!.!.!. 1.:.!.!.!.!.:.! Disk herbicide i' O i i' J i i. i' i' i'. i.aa..a..v. List.ii'iiiii... ==.e.e. Mulch i ii iii iiiiiiiiiiii % i % %%% % % %% %% %%%%.ii%oa : %%i %O %%i%%%%i :%%:!%:i%:%ii:' %iiiii ii '....O :...:... %%%.%%%%%%%%%%%i ::.:..:1...:!.::..v: ii i 0Ó ENERGY (kw -h /ha) Figure 1. Energy Requirements for the conventional system. Marana Agric. Center, SUNDANCE SYSTEM OPERATION Shred stalks i Uproot stalks Shred stalks 2 Subsoil list ' -O = ='-'- = = d = =' '-=' ' '-4= 28 Shape beds Qmm :!.!.!!!.r,l '. p O. O. p.. O.....v..a..v.a.a...v...vav.vvvv...,. p.... p ,... Mulch ENERGY (kw -h /ha) Figure 2. Energy Requirements for the sundance system. Marana Agric. Center, 43

7 USM SYSTEM OPERATION USN. :';,::Qtij:::s0::O:''i'1Z:ti:%ii'i.!':':y:+ÿs191; Oii i íoiiit3:i i. i PirQii.Ji.l'ei!ili:ii! i i. iofo."ls"rj ':.'j'ij Subsoil list Shape beds Mulch i'iiii'ii'iiiviiiiiiiii%'%i,..:.i.:..!i ENERGY (kw -h /ha) Figure 3. Energy Requirements for the USM system. Marana Agric. Center, SYSYEM TOTALS SYSTEM Convent 1ona1..4J...ObJ...J 0.000iJ.b..O:OJi vaa..o.. o<.. rrvor. v...r... J... voav.... o... o... oo..v... ov..j. :.,.Q.O4;!Qiii.i!...!!.iOi:iJ.:.i!.!.Q.Qi i.i...ji... :Oi:Q.:.iiiiiiiiiii:Jii0: J...J%J... JO J O0iJJii1i.OJ0O.O J.OO.:.;.!..:.0:..:...:.;.:.:.:..:.:..;.:::!O..:::.:::. 73 Sundance.vavrr...a..v...a..rr-.O w...v......J Ji.r... i USM JiO.OiïiiiJOiIi ioiiriijiij JiOii4iOi ioi.oi0 y 107 : : : :.. : :ti : : : : : :. :. : : : :: :: : : :..:. :. :...L: : : O:R 0 i L s0 ENERGY kw-h /ha) Figure 4. Total energy requirements for all systems. Marana Agric. Center, 44