Reduction of nitrogen fertilization by estimating soil nitrogen mineralization in paddy soil supplied with rice straw and rice straw compost every year
2006
Emoto, Y.(Shizuoka-ken. Citrus Experiment Station, Shimizu (Japan)) | Sugiura, H. | Matsumoto, M. | Yamamoto, M.
We studied the fertilization method for paddy rice plant with the compound fertilizer for suppling the insufficient nitrogen in basal fertilizer and top dressing. Soil nitrogen mineralization estimated by absorption spectrum at 420nm wavelength of exudates extracted with phosphate buffer at pH7.0. The experiments were conducted at a rice field with gray lowland paddy soil and supplied rice straw or rice straw compost for long period of time. The results obtained were as follows: 1. The measured amounts of mineralized soil nitrogen exceeded the estimated amounts in the plots supplied with rice straw and rice straw compost when analyzed in the panicle formation stage, but both figures became equivalent each another in the maturing stage. The discrepancy in the panicle formation stage may be caused by air drying effect of paddy soil because of fair weather and high atmosphere temperature continued for 9 days prior to transplanting. 2. The measured amounts of basal fertilizer increased and those of top dressing decreased than the estimated ones because of air drying effect of paddy soil. The yield and quality of rice grains in the test plots were the same to or better than those of control plots. 3. Thirty five to sixty percent of nitrogen fertilization in the conventional fertilization method could be reduced in this fertilization method.
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