Comparative Assessment of Vegetable Crop Performances and Ecological Indicators during Transition from Conventional to Ecological Agriculture

Abstract

Selected field vegetable crop combinations and increasing dosage of bio-char application, together with other alternative agronomic components of ecological agriculture (EA) were compared with conventional agriculture (CA) during the first three seasons of transition from CA to EA under hot-humid tropical conditions and sandy regasolic soils in Kalpitiya, Sri Lanka. The recommendations of the Department of Agriculture (Sri Lanka) was followed for managing conventional agriculture plots while alternative ecological options were followed for plant nutrient and pest managements. Capsicum-beet, Okra-beet and mae-spinach and radish-onion crop combinations could be selected for intercropping under ecological as well as conventional cropping systems based on their yield performances (Land Equivalent Ratio -LER) or other yield components. Even though plant growth rates and crop yields were lower at the beginning, EA was able to outrank CA by the third consecutive season. A bio-char amendment of 2 kg m-2 could be identified as the best among the different dosages tested. Soil N, P and K contents were increased while accumulation of Cd and Hg were reduced at the end of a three season long ecological agriculture practices. Insect pest/natural enemy incidence were not different between two cropping systems.