Modified phosphate rock by γ- poly glutamic acid and its effects on the growth of rapeseed seedlings and soil properties

The pot experiments of rapeseed seedling and the incubation test were used to investigate the modified phosphate rock through γ-poly glutamic acid (γ-PGA) on the growth of rapeseed seedlings and soil properties. Three soils, namely red soil, yellow cinnamon soil and yellow brown soil were sampled to conduct the experiments. The results show that biomass of rapeseed under the modified phosphate rock treatment is higher than that of other treatments in three soils, and the biomass under the modified phosphate rock treatment in red soil is significantly higher than that of the CK, and super phosphate (SP) treatments. In the three soils, the P content and the P uptake of rapeseed seedlings under the treatments added with γ-PGA are higher than those of the treatments without γ-PGA addition. Phosphate rocks modified with γ-PGA could significantly increase phosphorus uptake efficiency of rapeseed, and is good for phosphorus utilization. And phosphate rocks could increase soil available phosphorus content after being modified by γ-PGA. In the incubation tests, the tested phosphate rocks can affect the chemical properties of the three soils at different degrees, with increasing in soil pH value, soluble phosphorus content and exchangeable Ca, Mg content, decreasing in exchangeable Al content. These changes in three soils follow the order: modified phosphate rock phosphate rock CK.