IMPROVEMENT OF PHOSPHATE FERTILIZER APPLICATION TO Azolla

概要

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To improve the methods of application of phosphorus or supply of soil P to Azolla (A. microphylla), basal application, split application, inoculation of P-enriched Azolla, and soil disturbance were compared. Soil disturbance did not increase the floodwater P content. Phosphorus was applied to inoculum production plots to enrich Azolla with P. Thus, phosphorus-enriched Azolla could multiply 5-7 times after inoculation until it became P deficient. Trials on the methods of enrichment of Azolla with P showed that the best method was to broadcast twice 4.33 kg P (10 kg P_2O_5/ha) at 2-day intervals and to harvest Azolla 3 days after P application. Addition of P once or twice 2 weeks after the inoculation of P-enriched Azolla further increased the biomass production. Efficiency of P application was analyzed in terms of N gain in relation to the amount of P applied. This ratio in the P-enriched Azolla treatment was higher than the economically sound ratio-5-, and higher than or equal to that in the standard split application.
社団法人日本土壌肥料学会の論文