Developing Sustainable Soil Building Strategies for Tropical Fruit Groves within the South Florida Redland

Abstract

Tropical fruit production has become a lucrative industry in Miami-Dade County. Consequently, developing sustainable farming practices to be applied to these systems to ensure healthy soils and economically viable fruit production is becoming increasingly important. The study is focused on the incorporation of cover cropping as a management strategy for perennial tropical fruit production and its applications for local growers. Cover crops are plants that are grown to cover soil to reduce erosion, increase soil fertility, and enhance farmland biodiversity. The project was specifically designed to test the impacts of highly prolific legumes sunn hemp (Crotalaria juncea) and velvet bean (Mucuna pruriens), intercropped with young carambola (Averrhoa carambola) trees on soil and plant health parameters. Sunn hemp and velvet bean were grown for two 90-day growing seasons and were left to decompose as green manure after termination. Carambola trees and surrounding soil were monitored over a 1.5-year period to quantify changes among six fertilizer treatments. Along with the field study, surveys were formulated and distributed to local growers to assess likelihood of cover crop adoption within the community. The goals of this work are threefold: 1) to understand the impact of legume cover crops on soil parameters 2) to understand the interaction between legume cover crops and carambola health/fruit production 3) to understand the perceptions of local fruit producers concerning cover cropping as a management strategy. Results indicated that sunn hemp was most successful in biomass production and providing available nitrogen to soils, while velvet bean was most stimulatory for short-term soil microbial parameters. Sunn hemp treatments were comparative to poultry manure fertilizer for contribution of soil carbon and nitrogen over the sampling period. Trees treated with sunn hemp exhibited high fruit yields and exceeded other treatments in regard to tree health parameters. Surveys conducted amongst the Miami-Dade County agriculture community revealed that farmers were interested in learning about cover cropping and attending workshops and informational sessions. Through logistic regression analysis, likelihood to cover crop was positively influenced by farm size, previous experience with cover crops, believing the practice is economically viable, and valuing cover crop importance.