摘要
[目的]研究不同磷水平紫色土中油菜磷素吸收以及土壤生物有效性磷含量对外源碳、磷的响应,挖掘不同磷水平条件下,碳、磷提高土壤磷素有效性的潜力.[方法]供试高磷土壤取自蔬菜地,有效磷、全磷含量分别为 163.23 mg/kg、1.72 g/kg,低磷土壤取自粮田,有效磷和全磷含量分别为 3.93 mg/kg、0.31 g/kg.油菜盆栽试验设置不加碳不加磷(CK)、添加磷(+P)、添加碳(+C)、加碳加磷(+C+P)4 个处理,碳源为葡萄糖,磷为磷酸二铵.油菜种植 30 天后,测定油菜地上部生物量、磷含量,土壤微生物量磷(MBP)含量和磷酸酶活性,并采用基于生物有效性磷的分级方法(BBP法)测定土壤中CaCl2-P、Citrate-P、Enzyme-P、HCl-P含量.[结果]低磷土壤中,+P、+C+P处理油菜地上部生物量分别较CK处理提高了 239%、120%,地上部磷含量分别提高了 71.43%、58.33%,而高磷土壤中,添加碳、磷(+P、+C、+C+P)对油菜的生长无显著影响,但提高了油菜地上部磷含量,+P、+C、+C+P处理分别比CK处理高出 30.55%、33.45%、42.52%.与CK处理相比,低磷土壤中添加碳、磷对Enzyme-P提升最大,平均提高了 2.76 倍,+P、+C+P处理的CaCl2-P含量分别增加24.76%、27.72%,+C处理显著提高了Citrate-P含量,添加碳、磷(+P、+C、+C+P)对HCl-P均未产生显著影响;高磷土壤中+P、+C、+C+P处理降低了土壤中的CaCl2-P含量,以+C处理下降最为显著,比CK处理减少了 34.45%,而Citrate-P、Enzyme-P、HCl-P含量均有所增加,其中+P、+C、+C+P处理的Citrate-P含量相较于CK处理分别显著增加了 12.50%、17.43%、24.47%.低磷土壤+P、+C、+C+P处理的土壤MBP、酸性磷酸酶活性分别较CK处理提高了 28.80%～59.39%、5.96%～6.69%,而高磷土壤的MBP和酸性磷酸酶活性只对+C、+C+P处理有所响应,MBP含量相较于CK处理分别提高了 35.65%、37.08%,酸性磷酸酶活性分别提高了 5.33%、7.76%.[结论]低磷土壤中添加磷有利于油菜的生长,在高磷土壤中,添加磷只能增加油菜地上部磷的奢侈吸收,对生物量无促进作用.低磷土壤添加磷、碳均可提升土壤磷的生物有效性,而高磷土壤磷的生物有效性对外源碳的响应更显著.因此,低磷土壤中应同时添加碳、磷提高磷肥的效应,而高磷土壤应补充有机碳提升土壤中磷的生物有效性.
Abstract
[Objectives]We studied the effects of carbon and phosphorus additions on phosphorus uptake of rape and the bio-availability of soils under different phosphorus P levels,to explore the pathway of improving phosphorous fertilizer use efficiency.[Methods]A rape pot experiment was carried out,the high-P purple soil was taken from vegetable field,where available and total P content were 163.23 mg/kg and 1.72 g/kg,and the low-P purple soil was taken from a maize growing field,with available and total P content 3.93 mg/kg and 0.31 g/kg.Four treatments were set up,including:no carbon or phosphorus added(CK),adding phosphorus(+P),adding carbon(+C),and added carbon and phosphorus(+C+P),glucose was used as carbon source.After 30 days of growth,rape plants were harvested for measurement of aboveground biomass,and P content,the soil was sampled for measurement of microbial biomass P content(MBP),and phosphatase activity.Additionally,we analyzed the contents of four phosphorus components in the soil—CaCl2-P,Citrate-p,Enzymatic-P,and HCl-P,using the bioavailability-based phosphorus classification method(BBP).[Results]In low-P soil,adding P favored the growth and P uptake of rape,the rape biomass in+P and+C+P treatment was 6.48 and 4.21 g/pot,which was 2.39 and 1.20 times higher than the CK,and the P contents were increased by 71.43%and 58.33%.In high-P soil,addition of C and P(+P、+C、+C+P)did not significantly increase rape growth,but enhanced the plant P content,with increment of 30.55%,33.45%,and 42.52%in+P,+C,and+C+P treatment,respectively.In low-P purple soil,the addition of carbon and phosphorus significantly increased Enzyme-P levels by 2.76 times on average,+P and+C+P treatment increased CaCl2-P content by 24.76%and 27.72%,and+C enhanced Citrate-P content,but no any treatment showed significant effect on HCl-P.In high-P purple soil,all the treatments decreased CaCl2-P content,especially+C treatment resulted in 34.45%of drop,relative to that of CK;and compared to CK,+P,+C,and+C+P treatment increased Citrate-P significantly by 12.50%,17.43%and 24.47%.In low-P soil,+P,+C,and+C+P treatment increased soil MBP and phosphatase activity by 28.80%-59.39%and 5.96%-6.69%,while in high-P soil,only+C and+C+P treatment increased MBP by 35.65%and 37.08%,phosphatase by 5.33%and 7.76%.[Conclusions]In low-P soil,adding P could increase the growth and P uptake of rape,while in high-P soil,adding P could only lead to the luxurious P uptake of rape.Adding phosphorus and carbon could improve phosphorus bioavailability of low-P soil.However,the response of soil phosphorus bioavailability to external carbon is more significant in high-P soil.Therefore,in low phosphorus soils,both carbon and phosphorus should be added to enhance the effect of fertilizer,while in high phosphorus soils,organic carbon should be supplemented to improve the bioavailability of phosphorus.
维普
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