【目的】研究红壤地区施用磷肥对甘蔗吸收磷的影响及进行磷淋溶流失风险评估,为蔗区科学合理施用磷肥提供参考依据。【方法】田间试验设不同施磷量处理,测定蔗茎和蔗叶产量及磷素养分含量、土壤Olsen-P含量等指标;室内试验按种植区主汛期的年均降雨量分批次进行模拟降雨,分别收集易溶性和枸溶性磷肥淋溶液,分析磷浓度和总量。【结果】施磷处理比不施磷处理的蔗茎、地上部生物量分别提高了3.0%~8.3%和2.4%~7.1%,其中均为150 kg P_2O_5/hm^2处理增产最高;施磷比不施磷处理的地上部的磷素吸收量提高16.1%~30.1%,大于150 kg P_2O_5/hm^2施磷量处理间,磷素吸收量差异不显著;随施磷量的增加,土壤CaCl_2-P和Olsen-P含量分别提高35.9%~778.6%和25.8%~230.2%;淋溶液磷的浓度和总量均随土壤有效磷含量的增加而增加,增幅达26.38%~53.68%和23.67%~49.70%,且处理间增幅差异显著。施用易溶性磷肥的淋溶液中磷浓度比枸溶性磷肥高10.44%。【结论】施磷量为150 kg P_2O_5/hm^2对红壤地区甘蔗生长较好,但可使土壤淋溶液总磷浓度的提高0.03~0.05 mg/L,施用易溶性磷肥比枸溶性磷肥淋溶液中磷浓度高10.44%,磷淋溶风险更大。
[Objectives] The soil phosphorus balance and potential risk of phosphorus loss under different phosphorus application rates in sugarcane red soil in Guangxi were evaluated to provide reference for scientific and rational application of phos- phorus fertilizer and reduction of environmental pollution. [Methods] A field trial and simulated rainfall experiment were carried out. In the field experiment, five phospho- rus levels （0, 75, 150, 300 and 600 kg P2OJhm2） were set, the yield of sugarcane stems and leaves were measured, and their phosphorus content was determined to obtain aboveground P accumulation and P surplus in soil. After sugarcane harvest- ing, calcium magnesium phosphate and potassium dihydrogen phosphate were ap- plied to soil with different levels of phosphorus to conduct the simulated rainfall ex- periment based on monthly rainfall from May to September in Guangxi during 2000-2015. The leachate was collected to analyze the concentration and total amount of phosphorus to obtain the regression equations between available phos- phorus content in soil and the increase of phosphorus concentration in leachate. [Results] Sugarcane yield increased significantly when phosphorus application rate was 150 kg P：~OJhm2. When phosphorus application rate exceeded this value, the yield of sugarcane stems and aboveground part was also significantly higher than the treatment without phosphorus application, but the increase of yield was similar to the treatment with phosphorus application rate of 150 kg P2OJhm2. According to the relationship equation between phosphorus application rate and soil Olsen-P con- tent as well as the relationship equations between the increment of P concentration in leachate and soil Olsen-P content in the treatments with calcium magnesium phosphate and KH2PO4, the increment of P concentration in leachate was 0.02-0.04 mg/L when phosphorus application rate was 75 kg P2OJhm2; the increment of P concentration in leachate was 0.07-0.10 mg/L as phosphorus application rate was 600 kg P2OJhm
