增施钙镁磷肥协同平衡施肥对甘蔗地土壤酸化的影响OA

[Objective]The study aimed to analyze the effects of different fertilization modes on basic soil nutrients and sugarcane yield in sug-arcane fields,and explore the regulation mechanism of applying calcium-magnesium phosphorus fertilizer on the basis of balanced fertilization against soil acidification,providing theoretical support for mitigating soil acidification and sustainable sugarcane production in Guangxi.[Method]Based on the long-term positioning experiment initiated in 2008 in sugarcane-growing areas of Guangxi,four treatments were set up,including no fertilization(CK),conventional fertilization(CF),balanced fertilization(BF),and increased phosphorus fertilizer(BF+P,balanced fertilization supplemented with 50％calcium-magnesium phosphorus fertilizer).Soil pH,exchangeable base cations,pH buffer capacity(pHBC),soil nutrients and sugarcane yield in the recent five years were systematically determined after 16 consecutive years of ferti-lization.[Result]Compared with the initial soil in 2008(pH 5.86),after 16 years of long-term positioning experiment,soil pH under CK treatment only decreased by 0.04 units,while all three fertilization treatments(CF,BF,and BF+P)accelerated soil acidification,with soil pH decreasing by 1.98,1.74,and 0.95,respectively,and the corresponding soil acidification rates were 0.12,0.11,and 0.06 ΔpH per year.Compared with CF treatment,BF treatment significantly increased soil pH by 0.24 and reduced the soil acidification rate by 12.10％(P＜0.05,the same as below),effectively alleviating soil acidification.The contents of exchangeable hydrogen,exchangeable aluminum,and exchangeable acid decreased significantly by 53.98％,23.89％and 28.69％,respectively.Meanwhile,exchangeable magnesium,exchangea-ble potassium and total exchangeable bases increased by 25.93％,80.77％and 22.53％,respectively,with base saturation increasing by 6.17％(absolute value).Additionally,soil available potassium content increased by 114.22％,balancing soil nutrient supply and increasing average sugarcane yield by 12.19％in the past 5 years.On the basis of BF treatment,applying 50％additional calcium-magnesium phosphor-us fertilizer further increased soil pH by 0.80 and reduced the soil acidification rate by 45.87％.The contents of exchangeable hydrogen,ex-changeable aluminum,and exchangeable acid decreased significantly by 59.22％,91.22％and 87.93％,respectively,effectively slowing and controlling the soil acidification process.The core mechanism laid in that increased calcium-magnesium phosphorus fertilizer application significantly increased contents of exchangeable calcium and exchangeable magnesium,enhancing total exchangeable bases by 136.77％,raised base saturation by 35.74％(absolute value),and improved pHBC,thereby achieving mitigation and control of soil acidification.[Con-clusion]On the basis of balanced fertilization,an additional 50％application of calcium magnesium phosphorus fertilizer achieves the optimal effect in mitigating soil acidification by increasing contents of exchangeable base cations(mainly exchangeable calcium and exchangeable magnesium),which enhances soil buffering capacity,thus effectively reducing the soil acidification rate.Therefore,increased calcium magne-sium phosphorus fertilizer combined with balanced fertilization can be recommended as a key technical measure for soil acidification mitiga-tion in Guangxi sugarcane fields.