矿物调理剂对丘陵红壤天目小香薯产量和酶生态化学计量特征的影响

Effects of mineral conditioner on the yield of sweet potato and ecoenzymatic stoichiometry in a hilly red soil

【目的】采用田间小区试验研究施用矿物调理剂对天目小香薯Ipomoea batatas产量、土壤微生物生物量、酶活性及生态化学计量特征的短期影响,探明影响土壤微生物养分限制的主要因素,为改善南方丘陵红壤肥力提供理论依据。【方法】设置空白对照(ck),以白云石、钾长石为主要原料制备的矿物调理剂3 (W1)和6 t·hm-2(W2) 2个处理。于天目小香薯收获期测定产量和地上部生物量、土壤化学性质及碳、氮、磷循环相关酶活性。【结果】与ck相比,矿物调理剂显著降低了土壤交换性酸(P<0.05),且W2处理显著提高了土壤pH、碱解氮和有效磷质量分数(P<0.05),但对天目小香薯产量无显著影响。相比ck,W1处理显著提高了土壤微生物生物量氮(MBN)质量分数91.1%(P<0.05),W2处理提高了微生物生物量碳(MBC)质量分数67.1%(P<0.05),且两者均显著提高了微生物生物量氮磷比(MBN/MBP)(P<0.05),分别提高了148.2%和131.8%。相比ck,W1和W2处理均显著降低了酸性磷酸酶活性(P<0.05),分别降低了31.9%和45.4%,且W2处理显著降低了亮氨酸氨基肽酶活性(52.4%,P<0.05)。但两者对β-葡萄糖苷酶、纤维二糖水解酶和β-1,4-N-乙酰氨基葡萄糖苷酶(NAG)无显著影响。土壤酶生态化学计量特征分析发现:W2处理显著提高了酶化学计量的向量长度(19.7%,P<0.05),显著降低了向量角度(10.5%,P<0.05),表明施用高量矿物调理剂提高了MBC限制,而缓解了MBP限制。冗余分析表明:土壤pH、碱解氮、MBC、MBN是影响土壤酶活性及其化学计量特征的主要因子。【结论】施用矿物调理剂短期内可有效降低土壤酸度,增加速效养分含量,缓解土壤微生物磷限制,从而有助于降低南方丘陵红壤磷限制对作物生长的影响。图3表2参32。

[Objective]With a field survey,this study is aimed to investigate the responses of sweet potato(Ipomoea batatas)yield,soil microbial biomass,enzyme activity and stoichiometry to mineral conditioner application and determine the main factors affecting the status of soil microbial nutrient limitation so as to provide a theoretical basis for improving the fertility of hilly red soil in Southern China.[Method]With a non-amended control(ck),a mineral conditioner amendment which was prepared from a mixture of dolomite and potassium feldspar,was applied at 3(W1)and 6 t·hm−2(W2),respectively.[Result]Compared with ck,the application of mineral conditioner significantly decreased soil exchangeable acid content(P<0.05);The W2 treatment significantly increased soil pH,available nitrogen(N)and available phosphorus(P)contents(P<0.05),but had no significant effect on the yield of sweet potato;Compared with ck,W1 and W2 significantly increased soil microbial biomass nitrogen(MBN)and carbon(MBC)(91.1%and 67.1%,respectively,P<0.05),while both of them increased the ratio of microbial biomass nitrogen/phosphorus ratio(MBN/MBP)(148.2%and 131.8%,respectively,P<0.05);Compared with ck,W1 and W2 significantly reduced the activity of acid phosphatase(by 31.9%and 45.4%,respectively,P<0.05),and W2 treatment significantly reduced the activity of leucine aminopeptidase(by 52.4%,P<0.05),but they had no significant effect on the activities ofβ-glucosidase,cellobiohydrolase andβ-1,4-N-acetylglucosaminidase;Soil enzymatic stoichiometry showed that W2 significantly increased the vector length(by 19.7%,P<0.05)and reduced the vector angle(by 10.5%,P<0.05),indicating that the high amendment rate of mineral conditioner increased microbial C limitation and alleviated their P limitation.As was shown by redundant analysis,soil pH,available N,MBC and MBN were the main factors affecting soil enzyme activity and its stoichiometry.[Conclusion]The application of mineral conditioner can effectively reduce soil acidity,increase the available nutrient content,and alleviate soil microbial P limitation,thereby helping to potentially reduce the P limitation to crop growth in hilly red soils from Southern China.[Ch,3 fig.2 tab.32 ref.]