关键词: 旱地, 冬小麦, 降水量, 磷肥优化, 磷素吸收, 土壤磷盈余

Abstract:

【Objective】 The effects of phosphorus (P) fertilization on the yield, P uptake and utilization of dryland wheat under different precipitation patterns and summer-season precipitation were investigated to provide the theoretical basis and practical guidance for optimizing the management of P fertilizer application and increasing yield of dryland winter wheat.【Method】 This study was based on a winter wheat P fertilization experiment that started in July 2018 at three sites in Weibei dryland area of Plateau Loess, China. The field experiment included two treatments: optimized P application (+P), and no P application (-P). The precipitation, winter wheat yield, precipitation efficiency, soil water storage, P fertilizer use efficiency, wheat P uptake, and soil P budget under different precipitation years were analyzed over three years. 【Result】 The wheat yields in dry and intermediate years were 3 432 and 4 549 kg·hm^-2, respectively, while the wheat yield in wet year was 7 634 kg·hm^-2. Compared with the -P treatment, the +P treatment significantly increased the wheat yield by 5.8%. Overall, the winter wheat yield showed a linear plus platform correlation with annual precipitation and precipitation in the summer fallow season. In the dry years, the annual and summer-seasonal precipitation use efficiency under +P treatment were significantly lower than those in the -P treatment, with a decrease of 9.5% and 8.0%, respectively; however, in the wet year, they were significantly higher by 13.1% and 12.9% than those under -P treatment. Soil water storage in 0-100 cm soil layers in intermediate year was significantly lower by 10.5% and 10.8% than that under the dry and wet years, respectively, while in the wet year, the application of P fertilizer had no significant effects on soil water storage in 0-300 cm soil layers. Additionally, in the dry and intermediate years, the +P treatment significantly increased the topsoil available phosphorus contents by 29.1% and 17.8%, respectively. The P use efficiency increased with the increasing annual precipitation and summer-season precipitation and the partial factor productivity and agronomic efficiency of P fertilizer were the highest in the wet year, with increases of 74.0% and 176.3%, respectively, compared with the dry year. The soil P budget under +P treatment in the wet year was the lowest, significantly reduced by 67.9% and 62.9% than that in the dry and intermediate years, respectively. The soil P budget under -P treatment was deficient, and it was significantly higher in wet year than that in dry year and intermediate year. 【Conclusion】 Under P fertilizer input, winter wheat yield and P uptake and utilization had different effects in different precipitation year patterns. Therefore, it was necessary to consider the changes in precipitation when applying P fertilizer in dryland winter wheat production. Based on the similar results under the precipitation in summer season and annual precipitation, more attention should be paid to the precipitation in summer season, by which it could predict the target yield and optimize the P fertilizer application rate, in order to ensure the reasonable application of P fertilizer and improve crop yield.

Key words: dryland, wheat, precipitation, optimized phosphorus application, phosphorus absorption, soil phosphorus budget