Kan plianplaeng khong nitrogen nai dinna an nuang machak kansai watsadu luachai insri.

Rangsit soil, an acid sulfate soils, and Roiet soil, a sandy infertile soils, were used in the study. The results from the pot experiment showed that adding organic waste materials increased NH4+-N content in paddy soils. The increase in the amount of NH4+-N in the soil amended with organic waste materials was lower than that in the soil amended with chemical fertilizer. The amount of NH4+-release from organic waste materials differ in the decreasing order as follows: for Rangsit soils, castor meal > activated sludge from beer factory > sludge from whisky factory > filter cake > rice straw compost; for Roiet soils, castor meal > activated sludge from beer factory > sludge from whisky factory > rice straw compost > filter cake. The increasing order in the amount of the released nitrogen correlated inversely with the order of C/N ratio. The rate of NH4+ released of organic waste materials in Rangsit soils was slower than that in Roiet soils. The increase of soil temperature in the range of 20-30 C increased both the intensity and the rate of NH4+ released from organic waste materials under the submerged condition. This effect was significant in organic waste material with low C/N ratio in the Rangsit soils. The rate of decomposition and NH4+-N release or organic waste materials in paddy soils decreased when the rate of application was increased. It was also found that the total nitrogen uptake of the rice plant from the soils amended with organic waste materials through the whole duration of plant growth decreased in the following order: in Rangsit soils, chemical fertilizer > castor meal > activated sludge from beer factory > sludge from whisky factory > filter cake > check. Among the various kinds of organic waste materials examined, filter cake was the most effective in increasing pH of the soils. Organic waste materials enhanced algal growth and increased the amount of algal debris and mineralizable N in the upper layer (0-2 cm) of paddy soils.