1989 Annual Report for LS89-016
Development of a Low-Input Multiple Cropping System for Small-Scale Farms
Summary
A cropping system was developed in which various vegetable crops are planted sequentially with legumes strategically placed within the sequence to build up soil nitrogen (N) and allow for low-inputs of expensive N fertilizer. Fall-planted leguminous cover crops of hairy vetch, Austrian winter pea, and crimson clover were each followed by spring-planted 'Sundance' summer squash and 'Dasher' cucumber. Squash and cucumber crops were followed by 'Florida Broadleaf' mustard green and 'Vates' collard, respectively. The same vegetable sequences were also planted without benefit of cover crop. Three nitrogen (N) rates were applied to each vegetable crop: (1) the rate recommended by the Louisiana Cooperative Extension Service; (2) one half that rate; or (3) none. The experiment was repeated for three years at two locations in Louisiana, Southern University, Baton Rouge, and the Southern Development Foundation's Farm in Plaisance. The cover crop effect was usually greater with the spring-planted vegetables. Squash and cucumber following crimson clover and hairy vetch generally produced greater yields than those vegetables grown without preceding cover crop. The performance of Austrian winter pea was variable and was apparently adversely affected by wet conditions during 1991-1992. As a result, squash following Austrian winter pea in 1992 produced smaller yields than did squash following the other cover crops. Cover crops effects for fall crops while inconsistent, were greatest in the fall, 1992 when mustards following crimson clover and hairy vetch produced greater yields than other treatments. This trend was also noted with the collard crop. The complete elimination of N fertilizer resulted in reduced yields for all crops. However, yields of crops receiving one-half the recommended N were generally comparable to those receiving the full recommended rate regardless of previous cover crop. Results of this study demonstrate that cover crops can enhance the yields of sequentially planted vegetables, although their usage may not completely eliminate the need for additional N fertilizer. Furthermore, the performance of cover crops can vary from year to year because of climatic and environmental conditions. However, crimson clover and hairy vetch are apparently better choices for cover crops than Austrian winter pea in Louisiana and the humid southeast. The study also suggests possibilities for reducing N applications for vegetable crops to levels lower than those commonly recommended. Finally, the effects of cover crops beyond the first sequentially planted vegetable crop may take several growing seasons to become apparent.
Project Results
Objective One
Results of this study demonstrated that leguminous cover crops can enhance the
yields of sequentially-planted vegetables (summer squash, cucumber, mustard green, collard). Of the three cover crops evaluated, crimson clover and hairy vetch appear best suited for climatic conditions found in Louisiana and the humid southeast. The performance of Austrian winter pea was variable and was apparently adversely affected by wet conditions. Yields of the spring-planted vegetables following the cover crops generally were higher than those grown without the benefit of preceding cover crop. However, their usage may not completely eliminate the need for additional nitrogen (N) fertilizer sources since the complete elimination of N fertilizer usually resulted in reduced yields of the vegetable crops within the sequence. On the other hand, vegetables grown with one half the recommended N rate generally performed comparable to those grown with the full recommended rate regardless of the presence or absence of a preceding cover crop. These findings suggest the possibility for reducing N applications for vegetable crops to levels lower than those commonly recommended.
Objective Two
The economic feasibility of selected cropping sequences is still being assessed. Input costs (labor, fertilizers, chemicals, etc.), and yield data are being analyzed in order to determine differences in economic returns of the selected crop sequences. These data will be used to develop enterprise budgets and make farm recommendations relative to the selected cropping sequences as well as nitrogen fertilizer use. Finally, an effort will be made to determine if the data that was collected is comparable with the Planetor/Budgetor budget generator format.
Objective Three
Research/demonstration plots were established and maintained at two locations: The Southern University Horticultural Farm in Baton Rouge, LA and the Southern Development Foundation's (SDF) 300 acre farm. SDF is a small-scale farm component of the Southern Cooperative Development Fund, an organization with over 20 years experience in agricultural and economic development in the southeast. The farm is located centrally to a large concentration of small-scale farms, many of whom are African-American. Southern University's extension agent for St. Landry Parish was also involved in the project. Numerous farmers visited both sites to observe cover crops and cropping sequences.
Related research will continue beyond the SARE project expiration date. We are evaluating several weed control strategies utilizing cover crops, including low-input techniques. A split plot experiment has been established using the two best cover crops from the previous experiment. Crimson clover and hairy vetch, which were found to be more consistent in plant growth and subsequent nitrogen content than Austrian winter pea, were seeded in December, 1992. Treatments include bare ground (no cover), and three treatments for each cover crop. These include incorporating the cover and covering the rows with plastic mulch, and mowing the covers and planting vegetables in the remaining mulch. All vegetables will be transplants raised in the greenhouse. Pepper and cantaloupe were transplanted in May, 1993 in the treatments mentioned above. Two nitrogen rates (0, 1/2 recommended N) are being applied. The latter was selected because we found that reducing recommended N rates by one half in the previous experiment generally resulted in crops that did as well as those receiving the full rate recommended by the cooperative extension service. Only the bare ground treatments will receive chemical herbicides. Treatments are replicated three times. A fall crop of collard and cabbage will follow pepper and cantaloupe, respectively. Data will be gathered regarding yield, weed pressure, nutrient status of crops and soils, and economic and labor inputs. Materials and supplies for this experiment were purchased from remaining funds from the original project.
Objectives
(1) To develop viable vegetable sequential cropping systems that are ecologically sound and that minimize the use of agricultural chemicals.
(2) To determine the economic feasibility of selected low-input vegetable cropping sequences for small-scale farmers.
(3) To facilitate low-input technology transfer to small-scale producers by coordinating research and extension efforts through existing small farm organizations.
Resource Development
Three journal publications are being prepared involving yield analysis, economic analysis and nitrogen uptake and utilization. The cooperators gave presentations at eighteen conferences and extension meetings. They attended five additional conferences and wrote two newspaper articles about the project.