MASS LOSS AND NUTRIENT DYNAMICS ASSOCIATED WITH GREEN LEAF LEACHING OF CROPLAND AGROFOREST TREE SPECIES OF BANGLADESH

Nutrients leaching from green leaves can contribute a major role in cycling and supply of nutrient to the agricultural crops in any agroforestry system. This study focused on the nutrients (N, P and K) leaching from green leaves of Acacia auriculiformis, Eucalyptus camaldulensis, Mangifera indica, Artocarpus heterophyllus, Litchi chinensis, Khaya anthotheca and Swietenia macrophylla as the common cropland agroforest tree species of Bangladesh. Green leaves of the selected species were leached in deionized water and the experiment was continued up to 192 hours. Mass loss (%) of green leaves, Electrical Conductivity (EC) and Total Dissolved Solid (TDS) of leaching water of each species showed significant (p 0.05) curvilinear relationship with leaching time. Initial concentration of NH4, PO4 and K in leaching water of green leaves of individual species was found to increase significantly (p 0.05) up to 72 hours and remained almost constant at the later stages. All the tree species showed similar pattern K NH4 PO4 of nutrients release during the leaching process. The highest concentration of 3,242 ppm NH4 was observed for S. macrophylla, highest concentration of 1,934 ppm PO4 was detected for L. chinensis and highest concentration of 9,258 ppm potassium was found for A. auriculiformis. This study showed that E. camaldulensis was the best in terms of nutrient return through green leaves leaching process followed by A. auriculiformis and L. chinensis.