Optimum rate of fertilizer application for qing-geng-cai [Brassica rapa var. chinensis] cultivation in a rain-cover plastic house
2008
Homma, M.(Gunma-ken. Agricultural Technology Center, Isesaki (Japan)) | Sunaga, F. | Shoji, T. | Koshiba, M.
In the cultivation of Qing-geng-cai in a rain-cover plastic house, the application of a nitrogen fertilizer has an appreciable effect on crop yield. Further, the rate of nitrogen fertilizer application, 10 kg/10 a, is optimum because the quality and the yield of the crop attained upon the application are equal to those attained upon the application of conventional fertilizers for all seasons. On the other hand, phosphate and potassium fertilizers have very little effect on the yield. However, the application of these fertilizers is necessary as they replenish the soil nutrients that are lost due to continuous cropping. Therefore, based on amount of nutrient absorption, the optimum rate of phosphate and potassium fertilizer applications is 14 kg/10 a and 10 kg/10 a in summer and 20 kg/10 a and 14 kg/10 a in winter and spring, respectively. Further, as the measures of the cultivation in the field which excess phosphate accumulated in the soil, cultivation can be carried out without using the phosphate fertilizer when Truog-P2O5 in the soil exceeds 80 mg/100 g.
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