Supported by the National Key R&D Program of China (Nos. 2017YFD0200200 and 2017YFD0200202）
【Objective】 Soil organic phosphorus (P) is one of the important P sources for plants. A large number of studies have shown that rhizospheric processes improves bioavailability of soil organic P through stimulating mineralization of soil organic matter. 【Method】 In the present study, investigation were made of contributions of the rhizospheric processes of maize and faba bean to mineralization of soil organic P through an experiment combining root mat culture in greenhouse and in-situ measurement in the field, and exploration done of effect of soil organic P concentration on organic P mineralization in black soil, which is high in organic matter concentration. 【Result】No big differences were observed in dry weights of shoot and root of the maize and faba bean in greenhouse between low P (CK) and high P treatments (NPKM); Root/shoot ratio of the maize reached 0.25 in either treatment, and was 0.08 higher than that of the faba bean in CK and 0.07 higher in NPKM. Fertilization did not affect much P concentrations in shoot and root of the maize, and neither in shoot of ther faba bean. However, it did increase P concentration in root in the faba bean in NPKM by 57.6% as compared with CK. Rhizosphere pH of the maize in CK was 0.09 higher than the pH in bulk soil, and rhizosphere pH of the faba bean in NPKM was 0.11 higher than the pH in bulk soil and 0.09 higher than that of the maize. Acid phosphatase (APase) activity in rhizoshpere of the maize was significantly higher in CK than in bulk soil. No significant difference was observed in APase activity between rhizosphere and bulk soil. APase activity in rhizoshpere of the faba bean was 93.4% higher than that of the maize in NPKM. Soil organic P concentration in CK varied in the range of 214 mg·kg-1 ~ 218 mg·kg-1, and was 103%～171% lower than that in NPKM. Organic P in rhizosphere was depleted by crops in NPKM and by 138 and 86 mg·kg-1 with maize and faba bean, respectively. The organic acid anions in rhizosphere of the maize and faba bean included tartrate and malate anion. Tartrate concentration in rhizosphere of the maize was 77.0% lower in CK than in NPKM, and Tartrate concentration in rhizosphere of the faba bean did not vary much between in CK and in NPKM. In the field, rhizosphere pH of the maize was higher in CK than in NPK, NPKS and NPKM. Compared with the pH in bulk soil, rhizosphere pH of the above four treatments decreased by 0.3~0.51 units. Rhizosphere pH of the faba bean did not differ much between NPKM and NPKS. But pH of bulk soil was significantly lower in NPKM than in NPKS. But, NPK was significantly lower than all the other treatments in pH of bulk soil and of rhizosphere soil. APase activity was higher in rhizosphere than in bulk soil in all the treatments. No significant difference was observed in APase activity in rhizospheres of between the treatments. And APase activity in bulk soil did not vary much with treatment. Malate concentration in rhizosphere was higher in NPKM than in CK, but did differ much between CK, NPK and NPKS.【Conclusion】Mineralization of rhizosphere organic P was regulated by both rhizosphere processes and concentration of organic P in soil. Long-term fertilization promotes accumulation of organic P in black soil and increases concentration of the substrate of mineralization, which is beneficial to mineralization. Rhizospheric process of maize in the field enhances this process, thus maintaining P supply intensity in the root layer. Thus, building a high organic P pool and selecting crop varieties that are highly efficient in using organic phosphorus is an effective strategy to maintain P supply capacity of black soil and achieve the target of reducing P fertilization and improving its efficiency.
于星辰,刘 倩,李春杰,朱 平,李海港,张福锁.根际过程和高底物浓度促进黑土有机磷矿化[J].土壤学报,2019,56(4):953-963. DOI:10.11766/trxb201808280389 YU Xingchen, LIU Qian, LI Chunjie, ZHU Ping, LI Haigang, ZHANG Fusuo. Rhizospheric Processes and High Substrate Concentration Stimulating Mineralization of Soil Organic P in Black Earth[J]. Acta Pedologica Sinica,2019,56(4):953-963.复制