Potential Nitrogen Mineralization of Agricultural Wastes in Typic Natraqualfs: Implications for Jasmine Rice

Abstract

ABSTRACT Problems of salt-affected soils can be alleviated by organic amendments, but their nitrogen (N) mineralization pattern, crucial to providing proper N synchronization with crop demand, can differently be influenced by salinity and sodicity. An incubation study was carried out objectively to investigate the mineralization and kinetic release of N in three organic wastes (OWs) – rice husk (RH), rice straw (RS), burnt rice husk (BRH) in saline-sodic (SS) and sodic (Sod) soils. The OWs were mixed into the soils and inorganic N was measured under aerobic condition (field capacity) for 28 days followed by waterlogged condition until day-112. The mineral N mineralized from all OWs was, on average, <20% of N input released into the mineral N pool with RS mineralized the highest. Mineralization occurred less in SS than in Sod soil. Nitrogen mineralization peaked at 28 days with net immobilization observed after 21-day of waterlogged condition. The mineralization rate and mineralizable N pool of these OWs had a better fit to two-pool than first-order model, showing the highest quantities in respective RS, RH and BRH and fast N pools constant rate greater in SS than in Sod soils. Net N mineralization differed among OWs, soils and incubation times. The N mineralization pattern of OWs was a function of both N sources and soil salinity. The pool and rate of mineralizable N were predicted from the initial material’s total N. The findings can lead to proper N management for jasmine rice in salt-affected soils using inorganic wastes to partially supply N.