| In order to explore the transformation and availability of phosphorus fractions and to establish theoretical basis for phosphorus efficient utilization and management under maize and soybean intercropping system.Based on field experiment and the rhizobox experiment, this paper compares the aboveground biomass of maize and soybean, phosphorus accumulation of shoot, total phosphorus, available phosphorus, phosphorus fraction and acid phosphatase activity of rhizosphere and non-rhizosphere soils under different planting patterns and different phosphorus fertilization. The main results are as follows:(1) There were no significant difference between grain yield and straw yield of maize under M/S and MM treatments.The straw yield of monoculture soybean was also significantly higher than intercropping soybean. The rhizobox experiment result indicated the straw yield and grain yield of intercropped maize with non root separation (N-RS) was significantly higher than intercropped maize with root separation (RS) and mono maize. In soybean maturity, straw yield of intercropped soybean with no separation was significantly higher than that of RS and SS treatments.(2) The aboveground phosphorus content of mature maize under maize-soybean relay strip intercropping (M/S) was higher than MM treatment in field experiment by 3.1%.The aboveground phosphorus content of intercropped soybean (M/S) was significantly lower than monoculture in soybean mature stage. The rhizobox experiment result indicated that the shoot phosphorus content of intercropped maize without root separation was significant higher than that of root separation and monoculture maize in grouting stage. In maize maturity, the shoot phosphorus content of intercropped maize without root separation was significant higher than that of monoculture maize without and with root separation, respectively increased by 11.1% and 8.9%.In branching stage of soybean, the N-RS shoot phosphorus content of intercropped soybean was significantly lower than other treatments, while in the maturity was significantly higher than other treatments.(3) During the maturity stage, the total phosphorus content in rhizosphere soils of M/S treatment for maize was significantly higher than that of rhizosphere soil of MM treatment. The total phosphorus content in rhizosphere and non-rhizosphere soils of M/S treatment were significantly higher than that of SS treatment in maturity of soybean.The rhizobox experiment result showed that during maturity stage, the total phosphorus content in rhizosphere soil of intercropped maize was higher than those of monoculture maize. In branching Soybean, the total phosphorus content in rhizosphere soils of intercropped soybean without root separation was higher than that of intercropping with root separation and monoculture soybean.The available phosphorus content in rhizosphere soil of MM treatment for maize was significantly higher than that of M/S treatment. The rhizobox experiment result showed that available phosphorus content in rhizosphere soil of intercropped maize without root separation was lower than that of monoculture in grouting and maturity stage. The available phosphorus content in rhizosphere soil of N-RS intercropped soybean was significantly lower than that of monoculture soybean in maturity stage.(4) The H2O-Pi, NaHCO3-Pi, NaOH-Pi and NaOH-Pi contents in rhizosphere soil of M/S treatment for maize were lower than those of MM treatment. The NaHCO3-Po, NaOH-Pi and HCl-Pi contents of M/S treatment in rhizosphere soil for soybean were lower than those of SS treatments in maturity stage. The rhizobox experiment result indicated that the NaHCO3-Pi, NaOH-Pi and NaOH-Po contents of N-RS intercropped maize were lower than those of RS intercropped maize in maturity stage. Compared to monoculture maize, the H2O-Pi, NaHCO3-Pi, NaOH-Pi and NaOH-Po contents of N-RS intercropped maize were lower in maturity stage. The NaHCO3-Pi and NaOH-Po contents of N-RS intercropped soybean were lower than those of RS treatment under intercropped soybean and the H2O-Pi, NaHCO3-Pi, NaOH-Po contents of N-RS intercropped soybean were lower than those of monoculture soybean.(5)The acid phosphatase activity of M/S treatment for maize in rhizosphere and non-rhizosphere soils were significantly higher than MM treatment, and were respectively1.25 andl.09 times those of MM treatment. The rhizobox experiment result indicated that the acid phosphatase activity in rhizosphere soil under N-RS intercropped maize were respectively 1.19,1.15 and 1.23,1.29 times those under N-RS and RS monoculture maiz in grouting and maturity stage. The acid phosphatase activity in rhizosphere soil under N-RS intercropped soybean were respectively 1.06,1.19 and 1.07, 1.23 times those under RS and N-RS monoculture soybean in branching and maturity stage.(6) The straw yield of intercropped maize which was fertilized phosphorus for maize and soybean(M/S-P2) was higher than that of no phosphorus fertilizer (M/S-P0).The straw yield of intercropped soybean with phosphorus fertilizer for maize and soybean (M/S-P2) and only for maize(M/S-P1) were significantly higher than that of no phosphorus fertilizer (M/S-P0).In rhizobox experiment, the straw yield of maize were significantly improved with the increase of phosphorus fertilizer application.But the yield of grain of maize which were fertilized phosphorus only for maize (P1) and for maize and soybean (P2) were significantly higher than maize without phosphorus fertilizer (P0) in maturity stage. In soybean maturity, the grain yield of P2 treatment was higher than that of P0 and P1 treatments. indicating that phosphorus fertilizer application can increase the straw yield and grain yield of intercropped maize and soybean.The aboveground phosphorus content of maize in M/S-P2 treatment was significantly higher than M/S-P0 treatment. The shoot phosphorus content of soybean in M/S-P1 and M/S-P2 treatments were significantly higher than M/S-P0 treatment. In maize grouting and maturity stage of rhizobox experiment, the aboveground phosphorus content of maize in P1 and P2 were significantly higher than P0 treatment. In maturity of soybean, shoot phosphorus content of each treatment was not significantly different.(7) The increase of phosphorus fertilizer improved the total phosphorus of maize and soybean in rhizosphere soils under M/S-P0. M/S-P1 and M/S-P2 treatments.In rhizobox experiment, phosphorus fertilizer can increase the total phosphorus of maize and soybean in rhizosphere soil under P1 and P2 treatments as the same with field experiment.The available phosphorus of maize and soybean under M/S-P1 and M/S-P2 treatments were significantly higher than M/S-P0 in rhizosphere and non-rhizosphere soils. The available phosphorus of maize in rhizosphere under M/S-P1 treatment was significantly higher than M/S-P0 and M/S-P2 treatment.(8)The acid phosphatase activity of intercropped maize in rhizosphere soil was significantly higher with the increase of phosphorus fertilizer. The acid phosphatase activity of intercropped soybean under M/S-P2 treatment was significantly higher than M/S-PO and M/S-P1 treatments. In rhizobox experiment, the acid phosphatase activity of maize and soybean in rhizosphere soils were significantly different under P0, P1 and P2 treaments. |
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