Lessons Learned in Conservation Tillage Vegetable Systems in the Sub-tropics and Tropics

Tropical smallholder farmers operating under low-external-input (LEI) conditions rely upon non-intensive on-farm or locally available inputs for agricultural production; however, conventional resources are limited in the tropics and there is sparse data regarding the sustainability of tropical LEI agroecological systems. The primary objective of these studies is to develop tropical cover crop technologies for use as surface mulch in minimum-till vegetable systems to provide alternative weed management strategies and ensure competitive vegetable yields. Cover crop cultural practices including species selection, seeding date and termination strategies, and the manner in which they influence weed diversity and density as well as vegetable crop yield and quality are the primary issues to define. Vegetable system research conducted in three subtropical/tropical locations (Florida, Puerto Rico and the U.S. Virgin Islands) has resulted in several key lessons concerning LEI systems. Successful systems are associated with: 1) cover crop species selection that do not exhibit post-termination regrowth traits; 2) significant cover crop surface mulch that is retained throughout the vegetable crop season; and 3) a reduction in weed establishment leading to reduced weeding frequency. Limitations to the system include a limited number of cover crop species that respond to roller-crimper termination and the overall additional management effort required relative to traditional vegetable systems.