Developing Sustainable Dryland Cropping Systems in SW Colorado and SE Utah Using Conservation Tillage and Crop Diversification

Developing Sustainable Dryland Cropping Systems in SW Colorado and SE Utah Using Conservation Tillage and Crop Diversification

Summary

Winter wheat yield at Yellow Jacket, CO and to a lesser extend at Eastland, UT was significantly better after a 13-month fallow than after pinto bean, chickpea, corn, safflower, or oat. This was due to earlier wheat seeding and more available soil moisture after fallow than after spring grains. Furthermore, minimum tillage resulted in higher wheat yield than conventional tillage at Yellow Jacket. Cutworm activity and damage were minimal in the spring of 2002 but high moth counts in August through October at Yellow Jacket and Eastland indicate a high risk of potential crop damage in 2003.

Objectives/Performance Targets

Research Objectives:

1. Determine the effectiveness of alternative soil and crop management systems on crop yield, soil and water conservation, soil fertility, and pest management.

2. Evaluate the costs and returns of these systems in the context of the whole farm enterprise.

Educational Objectives:

1. Increase grower awareness and adaptation of conservation tillage practices.

2. Provide information on alternative cropping systems and how they can be used to enhance the sustainability of dryland cropping systems in the project area.

Accomplishments/Milestones

The 2001-02 crop season was one of the driest on record in the Four Corners area. It followed two years of below-average precipitation. At Yellow Jacket, CO the total precipitation from October 2001 to August 2002 was 3.5 in. or 24% of normal. September rainfall was above normal (2.68 in. vs. 1.56 in.) but came too late for most of the 2002 crops. Winter wheat production at the Yellow Jacket site averaged 12.5 bu/acre with a huge difference between wheat after fallow and wheat after spring grains. Wheat after a 13-month fallow averaged approximately 21 bu/acre compared to 4 bu/acre (0 to 8.7 bu/acre) on average for wheat after pinto bean, chickpea, corn, oat, or safflower. The higher wheat yield after fallow is likely due to earlier seeding and more available soil moisture at planting. This is similar to what happened in the Year 2000, although wheat yields were generally higher in 2000 than in 2002 due to slightly better weather conditions in 2000. Wheat after fallow produced significantly more grain with minimum tillage (MT) (24.7 bu/acre) than with conventional tillage (CT) (17.2 bu/acre) at Yellow Jacket in 2002 and could be attributed to more available soil moisture at planting with minimum till.

Winter wheat yields were even lower at Eastland, UT and at Goodman Point, CO because of late planting and low moisture availability. At Eastland, wheat after fallow was re-seeded twice due to soil crusting and did not emerge until spring e.g., at the same time as wheat after pinto bean. Still, wheat after fallow (11.4 bu/acre) out-produced wheat after beans (4.3 bu/acre). Winter triticale produced approximately 6 bu/acre after pinto beans and less than 1 bu/acre after corn (after safflower). Wheat after pinto beans averaged 4.7 bu/acre at Goodman Point. Wheat after chickpeas produced less than one-bushel per acre both at Yellow Jacket and Goodman Point. Wheat protein averaged 19% at Goodman Point, 17% at Yellow Jacket, and 15% at Eastland.

Oat, safflower, corn, chickpea, and pinto bean were planted on April 12, May 7, May 15 (corn and chickpea), and June 14, 2002, respectively. Oat, safflower, and corn had good emergence and stand but run out of water quickly. Chickpeas and pinto beans were planted in mostly dry soil resulting in poor emergence and growth since there was very little precipitation through July. Similar conditions existed at Eastland and Goodman Point. None of the spring crops were harvested at any of the experimental sites, although safflower could have yielded approximately 150 lb/acre in the wheat-safflower-fallow rotation and 400 lb/acre in the triticale-safflower-corn rotation, if it were harvested. The cooperator at Eastland did not think it was worth his time to harvest safflowers, especially since they were late to mature and there was a heavy infestation of Russian thistle in some of the plots.

Cutworm activity was monitored at Yellow Jacket and Eastland as part of the Western Region IPM Cutworm Regional Survey and Forecast Project. Cutworm outbreaks represent serious but sporadic events in southwestern Colorado and southeastern Utah. The main crops that are attacked are winter wheat and alfalfa. The two main species of concern are the army cutworm [Euxoa auxiliaris (Grote)] and the pale western cutworm (Agrotis orthogonia Morrison). Very little cutworm activity or crop damage was observed during the last week of May at Eastland or Yellow Jacket. Adult cutworm moth totals (average of two traps) for Eastland were 484 pale western cutworms and 213 army cutworms during an 11-week period in August through October. This corresponds to a high risk for potential damage in 2003 from pale western cutworms and a low risk for potential damage from army cutworms. The moth totals for Yellow Jacket were 369 pale western cutworms and 1473 army cutworms in 13 weeks (20 Aug. to 12 Nov.). These numbers correspond to a high risk for potential damage in 2003 from both species. The threshold for potential damage the following spring is 200 moths for pale western cutworm and 800 moths for army cutworm.

Preliminary conclusions:
Of the three years since the field plots were established, 2002 was by far the driest followed by 2000, and to a lesser extend, 2001. Spring crops failed almost completely in 2000 and 2002. Winter wheat after fallow was superior to wheat after spring grains in those two years. There was also a yield advantage of MT wheat-fallow compared to CT wheat-fallow in 2001 and 2002. Growing one crop each year in the semi-arid environment of southwestern Colorado and southeastern Utah may not be feasible in the long-term. Two- or three-year (and possibly 4-yr.) rotations with one fallow year would be preferable. Soil disturbance (tillage) should be minimized to enhance soil water storage and conservation. These and other hypotheses will be tested for one more year, at no additional cost to WSARE, before making recommendations as to the (i) feasibility of dryland cropping systems in the project area and, (ii) the continuation and future direction of this project. With some luck (moisture) and thorough data collection and analysis, we will be able to:
(1) Confirm earlier results and formulate new hypotheses;
(2) Make meaningful comparisons and inferences regarding the economic feasibility of the cropping systems that have been tested;
(3) Identify trends and/or formulate relationships as far as soil fertility and pest dynamics are concerned and;
(4) Submit a proposal for the continuation of this project.

Impacts and Contributions/Outcomes

One workshop was organized on Feb. 20, 2002; in conjunction with the Southwestern Colorado Research Annual Advisory Committee meeting to discuss WSARE99-056 results to date and explore new avenues for research and education in the project area, such as organic farming and crop rotations involving a cover crop. A total of 34 people attended the workshop. The Principal Investigator later visited with several farmers and current and prospective project cooperators and made presentations at Soil Conservation District meetings in Montecillo, UT and Dove Creek and Cortez, CO to discuss the SARE project and present a proposal for its continuation beyond 2003. Tours of the field trials were planned for the summer of 2002 but cancelled because of the drought. A limited survey was conducted to find out more about cropping systems, challenges, and farming trends in the project area. This information along with the project and other research results was used in an oral presentation made by the PI at the ASA/CSSA/SSSA Annual Meetings in Indianapolis, IN on November 13, 2002. The title of the presentation was "An in-depth look at cropping systems in SW Colorado and SE Utah". The 2000 and 2001 project results were published in May 2002 in:

Berrada, A., G.A. Peterson, P.D. Ayers, T.M. Hooten, R.W. Hammon, R.L. Sharp, and J. Skouson. 2002. Developing Sustainable Dryland Cropping Systems in SW Colorado and SE Utah Using Conservation Tillage and Crop Diversification: 2000 & 2001 Results. Agric. Exp. Stn. Tech. Bull. TB02-2, Colorado State Univ., Ft. Collins, CO.

Farmers in the project area have appreciated the fact that we are doing "research and education that addresses dryland farming concerns in this area and not working only on irrigated agriculture where the results can be more immediate". This project, in addition to providing research-based information, has served as a catalyst for discussion and exchange of ideas relating to dryland cropping sustainability.