Effect of long-term applications of P fertilizers and crop residues on p adsorption and p balance in soils under corn-clover cropping system [electronic resource].

Includes reference.

In the permanent experimental site, started in 1988. in the farm of Soils and Water Department, Assiut University. ground corn stover and ground clover straw (CR) were incorporated in the surface (0.00- 0.25 m) soil layer at an average rales of 5,45 ton fed⁻¹ year' and 3.71 ton fed⁻¹ year'. respectively. Six rates of fertilizer P fertilization (0. 100. 200, 300, 400, and 500 kg superphosphate fed⁻¹) were also applied each season. The results showed that the amount of Olsen's PI required to give the maximum P uptake in grains was equal to 46.8 and 51.4 ppm P in P fertilization management without crop residues (-CR) and with crop residues (+CR). respectively. In both P fertilization managements (-CR and +CR), P application significantly (p,0.05) and curvilinearly increased the dry malter accumulation and grain yield of corn plants. The P apparent balances showed that in both P fertilization managements (with and without CR), P fertilization rate of 62 kg P₂O₅ fed⁻¹ (400 kg SP fed⁻¹ each growth season) and higher were more than the requirements of corn-clover cropping system, and resulted in accumulation of P in soil. Phosphorous adsorption in the surface layer of soil treated with all levels of mineral P fertilizer appeared to be decreased with incorporation of crop residues into soil.

Summary in Arabic.

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