Reduced-Tillage Weed Management for Organic Farming
Sustainable Agricultural Systems Laboratory
2013 Annual Report
1a.Objectives (from AD-416):
Develop improved agronomic approaches for terminating cover crops, establishing crops, and suppressing weeds in reduced-tillage, high residue organic farming systems. Evaluate the performance of minimum-tillage organic systems in the long-term Farming Systems Trial.
1b.Approach (from AD-416):
Component experiments will be conducted by the Coooperator to investigate the following factors for improving and increasing the consistency of reduced-tillage organic systems. First, cover crop mixtures at selected ratios will be assessed for facilitation of cover crop kill, ease of planting and crop establishment, and weed suppression. Second, the timing of planting relative to cover crop kill will be assessed for interactions with the cover crop mixture factor. Third, the spatial distribution of cover crop species relative to planting patterns will be explored. Fourth, rescue cultivation approaches will be evaluated that effectively control weeds with minimum soil and residue disturbance. The long-term Cooperator's Farming Systems Trial (FST) provides a unique opportunity to determine the long-term effects of tillage in organic systems and how they compare to the well-known effects of tillage in conventional systems. The FST has recently been redesigned to include a tillage split (plow tillage versus reduced-tillage) within both the organic and conventional systems. We propose to enhance the capability of the Cooperator to collect data during the next five years at FST in order to more comprehensively determine weed population dynamics and crop performance in these systems. In addition, influences on soil quality and how these changes indirectly affect weed and crop responses to tillage will be determined. This information will be used by both ARS and the Cooperator to develop peer-reviewed publications as well as recommendations for improved no-tillage organic systems that can be distributed through field days, web-sites, and other appropriate technology transfer channels.
The third year of a field trial has been completed. The field trials were designed to determine the optimal timing of high residue cultivation in a cover crop-based organic rotational no-till soybean production system. High residue cultivation is designed to undercut weeds below the surface mulch residues. Early cultivation will have a small impact on weed root systems while late cultivation permits competitive effects from weeds on the crop. Defining the optimal cultivation timing is critical. An additional trial was conducted to determine the optimal timing and method of planting soybeans into a heavy cereal rye cover crop. Three years of field work have been completed. We are currently analyzing data and preparing manuscripts resulting from these trials.