Effects of Organic Wate Materials on Dynamics of Nitrogen in Submerged Paddy Soils

Abstract

Studies on the effects of organic waste materials (OWhl) on dynamics of nitrogen in Rangsit and Roiet paddy soils were conducted. OWM examined were rice straw compost (RSC), activated sludge (AS), whisky sludge (SW), filter cake (FC) and caster meal (CM). OWM increased NHicontent in paddy soils. The amount of N released from OWM was partly controlled by CIN ratio. The increasing order in the amount of the released N correspond to the decreasing order of CIN ratio. Time course of NHlformation varied among OWM and also between the two type of soils. OWM were classified into three group according to their time course of NHiformation : (1) slow release, RSC, FC (2) rapid release, AS, SW and (3) delayed rapid release, CM. The rate of NH; release in Rangsit soil amended with OWM was slower than that in Roiet soils. Nitrogen uptake by the rice plant was found to be correlated with N release in the soils and rice yield. OWM especially FC increased pH of the soils. Application of OWM enhanced reduction state of the paddy soils.