Use of Cover Crop Practices to Control Weeds in Integrated Lower-Chemical Input Systems of Vegetable Production
Objectives of this project include:
1) Evaluate and compare four different cover crop-vegetable cropping systems with a conventional vegetable cropping system for a) weed control, b) nitrogen cycling, c) soil biological activity, and d) overall economics in broccoli and peppers in a controlled experimental setting.
2) Verify on-farm three different cover crop-vegetable cropping systems and one conventional vegetable cropping system for a) weed control, b) nitrogen cycling, c) soil biological activity and d) overall economics in broccoli and peppers.
3) Utilize cover crop experimental plots and on-farm verification trials as venues for field days, farm tours and workshops to promote viable cover crop management strategies that are economical and practical for the control of weeds in vegetable crops.
Four cover crop management strategies were evaluated on a mixture of hairy vetch (20 lb/ac), crimson clover (10 lb/ac), rye and barley (24 lb/ac each). This mixture, screened from previous work (Creamer, 1992), was found to be superior both in terms of weed suppression and in biomass production, along with subsequent nutrient release. They were evaluated for economic and ecological function in comparison with each other and a fifth control
The five treatments can be described as 1) clean-tilled control; 2) strip-tilled cover crop, rotovated three weeks before and again immediately before transplanting; 3) cover crop killed/laid down with an undercutter bar, before planting; 4) flail mowed immediately before planting; 5) conventional vegetable cropping system using black plastic mulch for weed
control. The target crop for the first year was sweet peppers. For 1999 it was peppers again (due to Spring 1999 weather constraints) succeeded with broccoli.
Each of four replications of the five treatments were evaluated for soil microbial biomass, earthworms, nematodes, nutrients (soil and leaf tissue), nitrogen cycling, and weed density, community composition, and biomass.
Based on first year field experience, two farmer cooperators planted test plots of the cover crop mixture for on-farm evaluation of the same economic and ecological parameters.
The ecological responses to the different cover crop treatments were very different between treatments. Statistical significance is still being evaluated at the time of this report. The 1998 and 1999 growing seasons were very difficult for sweet pepper production, primarily due to an extended drought. The cooling affect of the systems resulting in heavier mulch contrasted dramatically from the heat generated from the plastic mulch system. This led to differing soil biology dynamics, which led to differing nutrient cycling dynamics. Economic evaluation is still be conducted.
We anticipate being able to characterize both the economic and ecological consequences of different cover crop management strategies in vegetables, including degree of weed suppression, dynamics with other crop pests, nutrient cycling capacities and practicality.