Phosphorus fertilization to the wheat-growing season only in a rice-wheat rotation in the Taihu Lake region of China

Crop production in the Taihu Lake Region (TLR) of China has been greatly improved by increasing phosphorus (P) fertilizer input. However, overuse has led to accumulation of P and increased the risk of environmental pollution. In this study, we investigated the effects of four P fertilization regimes in paddy soils at two field stations (CS1 and CS2) during four years of a rice-wheat cropping system. The fertilization regimes were as follows: P fertilization only during the wheat-growing season (PW), P fertilization only during the rice-growing season (PR), P fertilization during both the rice- and wheat-growing seasons (PR + W, current farming practice), and no P fertilization during either season (Pzero, control). The PW treatment did not reduce crop yield in either CS1 or CS2 compared to the PR + W. Moreover, soil Olsen-P concentrations during each rice-wheat rotation were maintained, and a positive increase in phosphate utilization efficiency by 1.2-3.6% (p > 0.05) was observed over the four rice-wheat rotations. In contrast, the PR treatment reduced the straw and grain yield of wheat by 8.74-43.2 and 19.4-47.7%, respectively, as did the Pzero treatment by 7.21-60.0 and 19.6-84.1%, respectively (p < 0.05). During the rice season, the PW treatment showed no significant differences in P fractionation and microorganism communities compared to the PR and PR + W treatments. The results suggest that the PW fertilization regime is suitable for rice-wheat rotation systems in agro-ecosystems such as the Taihu Lake Region of China.