ẢNH HƯỞNG CỦA LIỀU LƯỢNG VÀ CÁC DẠNG PHÂN LÂN ĐẾN NĂNG SUẤT CÂY TRỒNG VÀ CÁC DẠNG LÂN TRONG ĐẤT XÁM BẠC MÀU BẮC GIANG

To investigate the effects of rates and types of phosphorus fertilizers application on phosphorus form and crop yield in soil which applied for crop sequence spring rice - summer rice - winter maize on grey degraded soil, were conducted the field experiment at Luong Phong commune, Hiep Hoa district, Bac Giang province. The experiment included 8 treatments with 2 types of phosphorus (super phosphate and fused magnesium phosphate) and 3 rates of phosphorus application (40, 60, 80 kg P2O5 per ha per rice season, and 80, 100, 120 kg P2O5 per ha per maize season ). The research results showed that the phosphorus soluble in soil was highly depended on the rates of phosphorus application and it occupied from 2 to 28% of total mineral phosphorus in soil; aluminum phosphorus and calcium + magnesium phosphorus were dominant phosphorus form on grey degraded soil. Effect of super phosphorus on crop yield was higher than the effect of fused magnesium phosphate. Effect of phosphorus fertilizer application on summer rice yield was quite low, so for crop sequence spring rice - summer rice - winter maize on grey degraded soil, were recommend to apply super phosphorus at the rate 60 kg P2O5 - 0 kg P2O5 - 100 kg P2O5 per ha (no phosphorus fertilizer application for summer rice).