Effect of combined fertilization techniques on nitrogen and phosphorns in soil in the black soil region

In this experiment，the effects of fertilization techniques combined with organic manure，biological fertilizer and chemical fertilizer on nitrogen and phosphorus in the soil are investigated．The results show that compared with single chemieal fertilizer，soil full nitrogen content in every treatment of combined fertilizers increases by 0．05gkg，rapidly available N increases by 6．6～44．6mg／kg exceptforthetreatment II，soilfull phosphorus contentincreases by 0．15～0．29 gkg，rapidly available phosphorus increases by 15．68～51．07rag／kg；the recruitments of full nitrogen and rapidly available nitrogen increase by 0．2～0．25g／kg and 11．6～39．4rag／kg，respectively，and full phosphorus and rapidly available phosphorus increase by 0．09～0．24g／kg and 23．59～57．82mgkg，respectively．The economic benefits(net income)in every treatment increase by 19．4％ ～ 37．3％ compared with the control group．