Sustainable Vegetable Production in Rural Mississippi

Field experiments were conducted for two growing seasons (2001 and 2002) to compare the effect of conventional cropping system on “California Wonder” bell pepper, “Better Boy” tomatoes, “Georgia” collard green and “Beauregard” sweet potato yield and quality with those of transitional and organic cropping systems. While conventional involves monocropping under intensive use of purchased farm chemical, transitional and organic cropping systems involve crop-herb (sweet basil, dill, sage) intercropping under reduced-chemical and non-chemical input respectively. The effect of the cropping systems on soil and water quality were also investigated.

The studies were conducted at the Alcorn State University Incubator Farm ( McLaurin loam) and Model Farm (Memphis silt loam) located in Preston (East Mississippi) and Lorman (Southwest Mississippi) respectively. A split-plot arrangement in a randomized complete block design was used for each study established on a one hectare plot. The cropping systems made up the main plot, whereas, the test crop made up the subplot. Each field plot was established side by side and separated by uncultivated alley, about 1.5m wide on all sides, to prevent overlapping of the different farming system effects. Fertilizer application and pest control varied with cropping system. For the conventional farming system, fertilization which was based on soil test results were 120 kg ha-1 each of anhydrous ammonia, triple superphosphate and muriate of potash. For the transitional farming system, 80 kg ha-1 each of ammoniun nitrate, single superphosphate and murate potash. Additional fertilizer sources included on-farm nutrients from cover-cropping, and composting. For the organic farming system, rates of organic nitrogen, rockphosphate and sul-po-mag applications were 980 kg ha-1 , 850 kg ha-1 and 350 kg ha-1 respectively. Additional fertilizer sources also included on-farm nutrients from cover-cropping, and composting.

Data from both years indicated that conventional cropping system supports higher yields compared to transitional and organic cropping systems. However, the overall productions per given area for transitional and organic cropping systems increased substantially because of additional harvests from their respective herb companions. Therefore, when additional profits from the sale of intercropped herb are considered, transitional and organic cropping systems could be comparative to or greater than the conventional farming system. In 2001, organic cropping system increased fruit/leaf K, Ca, Fe and Zn compared to other treatments. In 2002, organic copping system also increased fruit/leaf K, Ca and Zn. Organic cropping system increased extractable P, K and Mg for both growing seasons compared to other treatments. Soil nitrate-nitrogen and orthophosphate were increased by the conventional cropping system compared to other cropping system. However, cropping system did not affect cation exchange capacity, organic matter, and acidity in either of the cropping seasons. The significant reduction in nitrate-nitrogen and orthophosphate in plots subjected to organic cropping systems indicate that this cropping system do not encourage water pollution by these nutrients, since phosphates and nitrate-nitrogen are known to be associated with surface and ground water pollution.

The results of the study were presented at the Mississippi Academy of Sciences in Biloxi, Mississippi, and at the Small Farmers Conference in Jackson, Mississippi. With the completion of the current growing season more data with photo documentation will be generated.