Reduction of chemical fertilizer at rice [Oryza sativa] growing on successive livestock manure applied paddy field

Effects of successive application of each livestock manure, such as, cow manure, chicken manure, and pig manure, on fertilizer reduction cultivation of paddy was studied by evaluating chemical property of the soil and yield and quality of the rice. The paddy fields used for the experiment were subject to successive application of each green manure for 8 years since 1993 at the rate of 1.5 tons /10 a/yr. The contents of available phosphorus (Av-P) in chicken manure plot, and in pig manure plot were 41.2 mg/100 g and 30.3 mg/100 g respectively. As these amounts were exceeded the required level for paddy, phosphoric acid fertilizer reduction cultivation was possible in the paddy field, where chicken manure or pig manure was applied successively. Further, exchangeable potassium in pig manure plot was 26.9 mg/100g, which was also exceeded the required level. These findings suggested that fertilizer reduction cultivation was possible in the paddy field where pig manure was applied successfully. The yield, the number of paddies per one square meter, the nitrogen absorption at harvesting stage, and the content of protein in brown rice were investigated from 2001 to 2004. Yield of brown rice in cow manure and chicken manure plots with half of basal and top dressing and in pig manure plot with no basal and half of top dressing gave 95% or more than that of conventional fertilizer plot. The number of paddies per one square meter was in the range of target number in Yamaguchi prefecture in all fertilizer reduction plots except in chicken manure and pig manure plots of non-fertilizer. Nitrogen absorption at harvesting stage in chicken manure and pig manure plots with half of basal and top dressing and no basal and half of top dressing was more than the conventional fertilizer plot. Content of brown rice protein of all fertilizer reduction plots except in no basal and half of top dressing in chicken manure plot was less than that of conventional fertilizer plot. Therefore, it can be concluded that half of basal and top dressing were able to reduced in paddy field, where cow manure and chicken manure were applied successfully, and complete basal and half of top dressing were able to reduced in paddy field where pig manure was applied successfully.