A five-year P fertilization pot trial for wheat only in a rice-wheat rotation of Chinese paddy soil: interaction of P availability and microorganism

Abstract

The need for efficient use of phosphorus (P) in agriculture has been highlighted recently by concerns about the finite amount of P fertilizer resources. However, in the Taihu Lake Region (TLR) of China, farmers’ injudicious and excessive use of P fertilizer has led to a dramatic spike in P accumulation. A five-year (ten consecutive crop seasons) pot experiment was conducted using four paddy soils with three P concentrations (2 P-rich, 1 P-moderate, and 1 P-deficient soils) from the TLR under four P fertilization regimes: P fertilization only for the wheat season (PW), P fertilization only for rice season (PR), P fertilization for both rice and wheat seasons (PR + W), and no P fertilization during either season (Pzero; control). Over 5 years, compared to the PR + W treatment, the PW treatment did not decrease crop yield (P < 0.05) because it could supply enough available P sources (124–210 mg kg-1 labile P and moderately labile P) for crop growth and similar microorganism community composition. Also, compared to the Pzero treatment, applied P fertilization significantly increased the concentration of labile P and moderately labile P. Additionally, applied P fertilization decreased acid phosphatase enzyme activity and increased the total relative abundance of microorganisms significantly in P-rich soil, although they decreased in P-deficient soil. Arbuscular mycorrhizal fungi (AMF) showed significant positive correlations with soil labile P (P < 0.05), which indicated that AMF played important roles in the transformation of P in the soil P pool. P fertilizer applied only for the wheat season may be a viable option for saving P fertilizer and sustaining crop yields in the current rice-wheat rotated system of China, and effective utilization of AMF which are related to P availability in the soil will be important in the future reasearch.