Effects of Phosphorus Availability on Plant Growth and Soil Nutrient Status in the Rice/Soybean Rotation System on Newly Cultivated Acidic Soils

Acid soils are worldwide spread, where low phosphorus (P) availability is considered as the major limiting constraint for crop growth, particularly on the newly cultivated acidic soils. Traditionally, the rotation system of rice with leguminous crops has been often used on acid soils. However, little is known about how P availability affects this traditional rotation system on acid soils. In the present study, two years of soil pot experiments had been done using rice (Oryza sativa L.) as the first crop and soybean (Glycine Max L.) as the second crop. The results showed that rice growth were significantly affected by P fertilization on acid soils. Sufficient P application increased plant height, shoot biomass, tiller number, and panicle dry weight compared to that of no P fertilization in both two years’ studies. The growth of following crop soybean was also influenced by P supply, and the P efficient genotype HX1 exhibited more adaptive to low P than the P inefficiency genotype BD2, as reflected by better growth of HX1 than BD2. Rhizosphere pH and soil nutrient status was significantly influenced by the rotation system. An increased tendency of rhizosphere pH was observed after the growth of rice and soybean. Soil N concentration was significantly increased after planting HX1 but not BD2. Furthermore, rice rotated with HX1 resulted in higher P fertilizer use efficiency (PFUE). Taken together, we conclude that the rice-soybean rotation with optimal P supply is a suitable agricultural mode on acid soils, and rotating with the P efficient soybean genotype could benefit more in soil nutrient status, which might increase the agriculture sustainability on acid soils.