Organic fertilizers are enriched in plant nutrients which may enhance the soil chemical properties. However, studies on the effect of long term fertilization on soil chemical attributes is yet lacking in Bangladesh. Therefore, an experiment was conducted to assess the changes of soil chemical properties as influenced by long term manuring and nitrogen fertilizer in silt clay loam soil under rice-wheat cropping system. The experimental plot received different organic materials for the last 26 years (1988-2014). Five types of organic materials treatments such as control (no manure), cowdung, compost, green manure and rice straw were applied at the rate of 0, 25, 25, 7.5 and 1.5 t ha-1, respectively in a yearly sequence. Three levels of nitrogen viz. 0, 75 and 100 kg ha-1 for rice and 0, 80 and 120 kg ha-1 for wheat were applied in this study. Long term application of different organic materials positively increased soil organic carbon and total N, P, S and decreased pH and K, Ca and Mg availability. Increase in soil organic carbon was found maximum under green manure and lowest in rice straw applied soil. The green manure contributed to the maximum accumulation of soil nitrogen. N dose of 80 kg ha-1 was found effective in increasing availability of soil nutrients.
Effect of Incorporation Levels of Green Manure Crops on Rice Yield and Soil Chemical Properties
