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南方丘陵红壤茶园长期受到酸沉降的胁迫,但茶树根际氮(N)、磷(P)转化过程对酸雨的响应及其机制尚不清楚.以江西典型丘陵红壤25年茶园为对象,开展p H 4.5、p H 3.5、p H 2.5及对照4种不同强度酸雨处理的原位模拟试验,于试验第3年测定根际和非根际土壤矿质N、速效P和相关酶的活性,并估测土壤N、P矿化速率,计算各变量的根际效应.结果表明:与对照相比,p H 4.5、p H 3.5和p H 2.5处理根际土壤NO3--N含量分别降低了7.1%、42.1%和49.9%,矿质N分别降低了6.4%、35.9%和40.3%,速效P分别降低了10.5%、41.1%和46.9%;根际氨化速率分别降低了18.7%、30.1%和44.7%,N净矿化速率分别降低了3.6%、12.7%和38.8%,P矿化速率分别降低了31.5%、41.8%和63.0%,但不同处理之间根际硝化速率差异不显著;根际土壤脲酶和酸性磷酸酶活性均表现为随酸雨加重呈增强的趋势(P<0.05).非根际土壤除NH4+-N外,其他有效N和P含量未随酸雨加重而改变;不同酸雨处理对非根际土壤氨化、硝化、N净矿化速率和P矿化速率的影响差异均不显著.根际NH4+-N、NO3--N、矿质N、氨化和净矿化速率均随着酸雨强度加重由正效应转变为负效应,而脲酶和酸性磷酸酶活性由负效应转变为正效应,但速效P和P矿化速率始终表现为负效应,硝化速率始终为正效应.综上所述,连续酸雨加重总体上抑制了根际N、P转化,降低其有效性,且不同程度改变其根际效应,从而影响茶园养分循环.
The red hilly tea plantations in south China were under acid stress for a long time, but its response to acid rain and its mechanism in rhizosphere rhizosphere of tea plant were not clear.With 25 years of tea plantations in typical hilly red soils in Jiangxi Province, H 4.5, p H 3.5, p H 2.5 and control were tested in the third year. The activities of mineral N, available P and related enzymes in rhizosphere soil and non-rhizosphere soil were measured and evaluated in the third year The mineralization rates of soil N and P were calculated and the rhizospheric effects of each variable were calculated.The results showed that the contents of NO3 - N in rhizosphere soils treated with p H 4.5, p H 3.5 and p H 2.5 were reduced by 7.1% , 42.1% and 49.9%, respectively. Mineral N decreased by 6.4%, 35.9% and 40.3%, respectively, and available P decreased by 10.5%, 41.1% and 46.9%, respectively; rhizosphere ammoniation rates decreased by 18.7%, 30.1% and 44.7% %, And N net mineralization rates decreased by 3.6%, 12.7% and 38.8%, respectively. P mineralization rates decreased by 31.5%, 41.8% and 63.0%, respectively, but there was no significant difference in rhizosphere nitrification rates between different treatments. Soil urease and acid phosphatase activities showed an increasing trend with the increase of acid rain (P <0.05) .Non-rhizosphere soil except NH4 + -N, the other effective N and P content With the increase of acid rain, the effects of different acid rain treatments on ammoniation, nitrification, N net mineralization rate and P mineralization rate of non-rhizosphere soil were not significant.The rhizosphere NH4 + -N, NO3 - N, mineral N, The rates of ammonification and net mineralization both changed from positive to negative with the increase of acid rain intensity, while the activities of urease and acid phosphatase changed from negative to positive, but the available P and P mineralization rates always showed negative effects, The nitrification rate is always a positive effect.In conclusion, the continuous acid rain restrains the conversion of N and P in the rhizosphere and reduces its effectiveness, and changes the rhizosphere effect to some extent, thus affecting the tea plantation nutrient cycle.