Minimum Tillage Systems for Cotton: Reduced Energy, Time, and Particulates

Minimum Tillage Systems for Cotton: Reduced Energy, Time, and Particulates

Summary

Energy requirements and airborne particulate (PM10) production of conventional and reduced tillage management systems for irrigated cotton production were compared at two locations in central Arizona. Tillage systems tested included: Conventional (shred, disk, rip, disk, list), Rotovator (shred, rotovate), Sundance (shred, root pull, rip/list), and Pegasus. At each site, conventional tillage produced the greatest quantity of PM10, whereas the Sundance and Rotovator produced between 41 and 60%, and the Pegasus system 5 to 15% as much PM10 as conventional tillage. Fuel consumption followed a similar pattern: Conventional tillage consumed 3.09, Sundance 1.26, Rotovator 1.70, and Pegasus 0.91 gal/acre.

Objectives/Performance Targets

1. 1. Compare three minimum tillage/controlled traffic systems to a conventional system in terms of profitability/efficiency, sustainability, and particulate generation.

   2. Evaluate commercially viable methods of reducing emissions from tillage operations.

   3. Demonstrate minimum tillage systems at field days, thereby permitting first hand observation by growers, extension personnel, etc. of their functionality and performance.

   4. Disseminate results through the popular press, Extension bulletins, and technical manuscripts.

Accomplishments/Milestones

1. Work accomplished to date:

a. Fabrication, testing, and modification of an implement-mounted PM10 collection device that can easily and quickly be transferred between field implements, along with a computer-based data collection system that records ground speed, fuel consumption in real time.

b. Data were collected for the 2000 growing season from field plots at two locations (Marana Agricultural Center and Maricopa Agricultural Center) in central Arizona comparing a Conventional Tillage system (shred, disk, rip, disk, list) with three minimum tillage systems: Rotovator (shred, rotovate), Sundance (shred, root pull, rip/list), and Pegasus (single combined operation). Data from the 2000 growing season have been analyzed and summarized.

All reduced tillage systems significantly reduced PM10 production relative to the conventional system. Data comparing the systems are shown in Table 1. The Sundance and Rotovator systems produced approximately half as much PM10 as the conventional system, whereas the Pegasus produced 5 to 15% as much. PM10 production from the individual operations are shown in Tables 2 (from the Maricopa site) and 3 (from the Marana site). In all cases, the shredding operation was the greatest contributor to airborne particulate generation, producing between 45 and 94% of the total PM10.

Fuel consumed during the various tillage operations, averaged between the two experimental sites, is shown in Table 4. The conventional tillage system consumed the greatest amount of fuel, followed by the Rotovator and Sundance systems. The most fuel efficient system was the Sundance.

Table 1. PM10 production from minimum tillage systems relative to conventional tillage.

Tillage System PM10 production (% of Conventional Tillage)

Maricopa Marana
Conventional 100a 100a
Sundance 49b 60b
Rotovator 41b 59b
Pegasus 15c 5c

Table 2. PM10 production from individual operations in tillage systems at the Maricopa Agricultural Center.

Conventional Sundance Rotovator Pegasus

Shred 45a Shred 92a Shred 94a – 100
Disk 1 7c Pull 8b Rotovator 6b
Rip 4c
Disk 2 23b
List 21b

Table 3. PM10 production from individual operations in tillage systems at the Marana Agricultural Center.

Conventional Sundance Rotovator Pegasus

Shred 68a Shred 83a Shred 91a – 100
Disk 1 2b Pull 17b Rotovator 9b
Rip 11b
Disk 2 12b
List 6b

Table 4. Fuel consumption used during individual operations in various cotton tillage systems (average of values from the Maricopa and Marana Agricultural Centers.

Tillage System Operation Fuel Consumption (gal/acre)

Conventional Shred 0.44
Disk 1 0.61
Rip 0.82
Disk 2 0.59
List 0.64
Total 3.09

Sundance Shred 0.45
Rootpull 0.36
Rip/List 0.45
Total 1.26

Rotovator Shred 0.45
Rotovate 1.25
Total 1.70

Pegasus Pegasus 0.91
Total 0.91

c. Data collection has started for the 2001 growing season.

d. PM10 production associated with individual tillage operations within each tillage system were quantified, so additional strategies for reducing PM10 emissions can be evaluated.

e. A presentation was made to commercial cotton growers, regulatory personnel, Extension personnel, and the public at the 2001 Arizona Cotton Field Day demonstrating equipment and summarizing results to date. A field side descriptive presentation was made at the 2001 Marana Field Day.

f. Cotton yield information was taken from each plot at harvest. Ginning has not been completed so final yield results are not known at this time.

g. The survey instrument to elicit willingness to adopt information has been designed. Pretesting will be completed by mid-January, 2002. The list of cotton growers (approximately 200) in Maricopa and Pinal Counties has been developed. The survey will be a census. The questionnaire has been submitted to the University’s Human Subjects Committee for approval. The baseline data for conventional tillage and the partial budget model have been completed.

2. Work remaining:

a. Finish collecting and analyzing field data from the 2001 growing season.

b. The willingness to adopt survey and analysis will be completed in 2002. The partial budget analysis of the three reduced tillage systems relative to the conventional system will be completed as well during that time frame. This economic research will produce a M.S. thesis, a journal article, and other joint publications with collaborating faculty.

c. Disseminate results via Extension Bulletins, additional grower field days, and produce at least one technical manuscript for publication in a refereed journal.

Impacts and Contributions/Outcomes

The main functions of this research are to demonstrate alternative tillage systems to cotton growers and to quantify potential reductions in associated time, fuel consumption, and PM10 production. The ongoing economic analysis of alternative tillage systems will delineate economic impacts of adopting alternative tillage systems. Air quality in the major cotton growing areas of central and Southern Arizona has been significantly degraded by airborne particulates, prompting the state to develop best management practices to reduce agricultural PM10 emissions. Lack of locally calibrated data has hampered that effort. The information generated through this study will be forwarded to the Governor’s Agricultural Best Management Practices Taskforce.

The economic analysis will generate an understanding of the willingness on the part of cotton growers to adopt alternative tillage systems given the relative economic advantages of these systems compared to conventional tillage practices. Factors influencing the adoption decision will be measured and analyzed.

It is hoped that the results of this study, disseminated directly to growers, will encourage adoption of alternative tillage methods. Information forwarded to the Governor’s Agricultural Best Management Practices Taskforce will be used in their continuing efforts to develop effective Best Management Practices. These impacts are expected be long-term, and measurable impacts may not be immediately apparent.

Collaborators: