Phosphate composition and transformation of fertilizer phosphorus in the light-chestnut soil of the Transvolga Saratov region under irrigation as depending on the fertilizer rates, methods of application, and time of interaction with the soil

摘要

The evolution of variations in the soil phosphate pool as related to different rates and methods of applying phosphate fertilizers has been revealed in a long-term field experiment on light-chestnut soil in the Transvolga Saratov region under irrigating conditions. It was shown that the fertilizer phosphorus under periodical (at 240 kg/ha every 3 years) or single (at 960 kg/ha once in 12 years) application of P_2O_5 was more available in the soil than the phosphorus from natural soil phosphates. With an annual application of P_2O_5 of 80 and 160 kg/ha for 12 years, the majority of fertilizer phosphorus was fixed in forms extractable by 0.5 N NH_4F.