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Developing Carbon-Positive Organic Systems Through Reduced Tillage and Cover Crop-Intensive Crop Rotation Schemes

Investigators
Delate, Kathleen
Institutions
Iowa State University
Start date
2008
End date
2012
Objective
Organic row crop and small grain producers rely on a suite of tillage operations to control weeds thought to lead to soil degradation. Further, many organic producers require off-farm inputs to maintain fertility. Thus, the long-term goal of this project is to provide a regional range of models of organic compliant no-till production systems to row crop and small grain producers that will avoid much if not all tillage operations and decrease the dependence on off-farm fertility inputs through the use of leguminous cover crops.

To reach this goal, over the course of 3 years, experiments in 6 states will be conducted and analyzed. All the experiments will demonstrate the use of an experimental roller/crimper field tool and integrate weed suppressing and soil building cover crops in an organic crop rotation.

The objective of each experiment will be to determine the effectiveness of the individual system in terms of soil quality by maximizing soil cover, minimizing erosion, and improving soil biological processes, increasing fertility, reducing ecological and economic costs and optimizing yield stability.

The experiments will be conducted at university and on-farm sites to provide analysis of system performance over a wide range of field and operator conditions. As the analysis of the experiments proceed a data base of field operations, weather conditions, soil health parameters, fertility profiles, crop performance, equipment effectiveness and weed suppression will be compiled. This data base will be used in compiling the yearly reports on the experiments

. Yearly reports will be presented to producers during annual field days at 6 university sites and 6 on farm sites. Additionally the reports will be presented to producers at regional organic conferences at Iowa State University in November and in February at the Upper Midwest Organic Conference in La Crosse, Wisconsin.

The 3 year result of the experiments will also be analyzed and presented to a peer reviewed journal for publication and for oral presentation at the annual conference of the American Society of Agronomy.

Other outputs will be extension publications from each participating university and additional presentations to local groups, such as the Neely-Kinyon Association in Greenfield, Iowa. A guidebook of Best Management Practices for Organic Soil Management will be published within 6 months of the end of the project to serve as a reference to all producers who seek to improve soil quality.

More information
Non-Technical Summary: Of the issues faced by row crop producers those resulting from soil erosion and compaction and fertility loss remain the most challenging. In an effort to address these issues of soil quality, at least in part, many producers have successfully adopted a system that limits the number of field operations required to produce a crop. This system is commonly referred to as no-till or reduced-till and relies on pesticides and synthetic fertilizers that are not allowed in a certified organic production system. The goal of this project is to design and execute a multistate, multisite, multiuser no-till system that will allow the organic row crop producer to forego a suite of tillage operations that may reduce soil quality and drive up the cost of production. Over the past few years the Rodale Institute has designed and experimented with a roller/crimper field tool capable of killing a weed-suppressing cover crop. When the roll/crimper is mounted on the front of a tractor with adequate horsepower, a planter can be mounted on the rear allowing planting to be accomplished at the same time as the cover crop is crushed. If the crushing of the cover crop results in a residual mat sufficient to suppress between row weeds, then the only remaining field operation is harvest. Integrating the roller/crimper tool with weed suppressing and soil-building cover crops into an organic rotation, soil quality will be enhanced by maximizing soil cover, minimizing erosion, and improving soil organisms and biological processes and reduce ecological and economic costs and optimize yield stability. Improvement in soil health will be measured by tracking nutrient cycling and biological processes, microbial populations and nitrogen mineralization rates. Enhanced ecosystem services on organic farms will be determined by measuring carbon sequestration, soil moisture and crop microclimates, weed suppression and biological controls through cover crop-intensive systems. Economic benefits will be measured by accounting for returns to organic farmers resulting from the reduction in costs of production through reduced tillage, specifically in field operation labor, reduced dependence on external sources of applied fertility, and lower energy costs. The information will be disseminated at field days and conferences, publications, appropriate and a guidebook of Best Management Practices for Organic Soil Management that utilize a farmer-centered approach to improve soil quality in organic systems. The expected primary impact resulting from this project will be a reliable determination of whether the roller/crimper field tool combined with cover crops can reduce the number of field operations now common among organic row crop producers and provide a significant contribution of soil quality and fertility. If this result is positive, it could reasonably be expected that the otherwise static organic grower base would increase. More producers would be willing to consider organic production because crops could be grown without excess weeds and tillage, soil quality would increase and they could receive premium pricing while reducing their overall economic and ecologic cost of production.

Approach: Organic crop rotations to examine the effect of tillage and crop sequence on soil quality, yields, weed populations and economic performance in spring 2008. Tillage and crop sequence treatments will be a randomized complete block design as a 2 X 2 factorial experiment: tilled (disking) versus no-till (rolling/crimping) and wheat-rye/bean-oat-vetch/corn versus wheat-hairy vetch/corn-oat-rye/bean and will be replicated 4 times at each location. Minimum plot size is 30 X 50 ft. Spring wheat will be the rotation baseline, followed by rye and hairy vetch to be terminated in the spring by disking or by roller/crimper. Pinto beans (western ND) and soybeans (all others) will be drilled into the cover crop treatments in 2009. Corn will be seeded into disked or rolled/crimped hairy vetch at all sites. In the no-till plots, a front-mounted roller/crimper and rear-mounted seeder will plant the corn and bean plots. Those same crops will be seeded in the tilled plots. Oats will be drilled in March 2010 in all plots and followed by rye and hairy vetch. In 2011, pinto beans (ND) and soybeans will be seeded directly into the disked or rolled/crimped rye and corn will be seeded into disked or rolled/crimped, hairy vetch. Soil samples will be collected from each plot in fall 2008 and 2010. Cover crop density will be determined by counting hairy vetch and rye plants in 3 areas in fall 2008, 2010 and spring 2009 and 2011. Fall and spring plant densities will be compared to determine winter hardiness and biomass. Disking or rolling/crimping effectiveness in terminating cover crop growth will be assessed 14 days after the operation. Stand establishment of corn and beans will be assessed 21 days after seeding by counting randomly selected plants in 17-ft of three 30-inch rows. Oat stand will be determined by counting plants within three 1-m2-quadrat areas in each plot. N fertility in corn plots will be evaluated in each treatment in the corn and bean years (2009 and 2011) through the Late-Spring Nitrate Test and the Corn Stalk Nitrate test. Bean and corn yields will be determined. Above-ground weed biomass will be determined prior to terminating cover crop treatments and when subsequent crops reach maturity. Light penetration will be used to assess weed suppressive potential of cover crops. From April to November monthly soil moisture will be measured at a sampling depth of 6, 12 inches and 36 inches in semi-arid sites. Weather conditions will be recorded at station sites. Data collected on-farm will include field histories, planting dates, equipment settings, field operations, crop conditions, weed pressure, weather and yields. Economic analysis will account for costs, yields, revenue and carbon inputs and outputs to calculate financial and energy budgets. Data will be analyzed by either repeated measures (between-subjects) ANOVA using the generalized linear models: REPEATED subroutine of SAS 8.1, or by the standard generalized linear model (PROC GLM) of SAS. Technology transfer techniques will include Field Days, conference and classroom presentations, websites and publications, including a guidebook on Best Management Practices for Organic Soil Management.

Funding Source
Nat'l. Inst. of Food and Agriculture
Project source
View this project
Project number
IOW05168
Accession number
213847
Categories
Pesticide Residues
Commodities
Produce
Grains, Beans, Legumes