- Agronomic: rye, grass (misc. perennial), hay
- Vegetables: cucurbits, peppers
- Animal Production: feed/forage
- Crop Production: cover crops, nutrient cycling, tissue analysis
- Education and Training: demonstration, display
- Pest Management: allelopathy, mulches - killed, mulching - plastic, physical control, weed ecology
- Production Systems: transitioning to organic
- Soil Management: green manures, nutrient mineralization, soil analysis, soil microbiology
Cereal-legume cover crop mixtures are of particular interest to growers because they provide the opportunity to effectively suppress weeds, control erosion, and scavenge leachable nitrate while also fixing atmospheric nitrogen. The goal of this project is to optimize seeding rates for mixtures of cereal rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth) based on a grower’s principal goals and crop management practices. The study involves the novel application of the replacement series experimental design, in which treatments will consist of a bare ground control and a gradient of 7 rye:vetch mixture proportions, from 100 % rye to 100% vetch. Following cover crop kill and incorporation, each mixture plot will be planted with both cucumber and bell pepper, and each crop will be grown with and without black plastic mulch. The performance of the cover crop mixture rates will be evaluated with respect to cover crop biomass accumulation, N-dynamics, weed suppression, subsequent vegetable yield and quality, and soil microbial biomass and community structure. In addition, cover crop performance measurements for plastic vs. no-plastic treatments will be compared in order to produce results relevant to both small- and large-scale growers. The outcomes of the proposed study will include greater awareness among vegetable growers of the benefits of cereal-legume cover crop mixtures, expanded adoption of such mixtures, and better decision-making regarding rye-vetch mixture seeding rates, potentially resulting in yield gains and input savings. Results will be communicated to both the scientific and grower communities through targeted publications, presentations, and field demonstrations.
Project objectives from proposal:
32 plots consisting of 4 replications of 7 rye-vetch mixture treatments plus a bare ground control were planted in September 2008 at MSU. The mixture treatments include the following proportions of rye:vetch: 100:0, 83:17, 67:33, 50:50, 33:67, 17:83, 0:100 and 0:0. With the rye monocrop seeded at 94 kg/ha and the vetch monocrop at 42 kg/ha, the resulting 50:50 mixture corresponds to a commonly cited optimal seeding rate from Clark et al. (1994)*.
Following cover crop incorporation in the spring, each mixture treatment will be divided in two—one half planted with 2 rows of slicing cucumber and the other half planted with 2 rows of bell pepper. For each crop, one row will be on black plastic mulch while the other will not. The experiment will help address the following 5 objectives.
Objective 1: Quantify trends in cover crop biomass accumulation and N-dynamics across mixture rates. Cover crop biomass will be sampled for each mixture treatment just prior to spring incorporation. Total biomass yield by species, as well as residue C:N, will be measured, and N-contribution will be tracked for each treatment (mixture rate x crop x plastic use) through bi-weekly sampling during the growing season.
Objective 2: Study the effect of mixture rate on weed populations and suppression. Two permanent 1?4 m2 microplots will be randomly marked in each non-plastic cropping area for evaluation of weed population density and species composition. Weed populations will be assessed three times during the growing season, corresponding to dates of cultivation.
Objective 3: Evaluate the effect of mixture rate on vegetable yield and fruit quality. Following harvest, total yield of cucumber and pepper for all treatments will be measured and fruit will be graded based on size and quality according to market specifications.
Objective 4: Evaluate the effect of mixture rate on soil microbial biomass and community structure. For soil samples from each treatment, microbial biomass will be estimated using the Chloroform Fumigation-Incubation method and functional diversity will be estimated with the BIOLOG method.
Objective 5: Study how the use of black plastic mulch affects optimal seeding rates for cover crop mixtures. PM treatments will receive no additional weed control while no-plastic treatments will be hoed uniformly at intervals in order to simulate small-scale organic production. Results of the above cover crop performance measurements for plastic vs. no plastic treatments will be compared in order to elucidate meaningful trends in seeding rate optimization.
*Clark, A.J., A.M. Decker, and J.J. Meisinger. 1994. Seeding rate and kill date effects on hairy vetch-cereal rye cover crop mixtures for corn production. Agron. J. 86:1065-1070.