为探究种植覆盖作物和施用有机肥对宁夏旱区枸杞园土壤活性有机碳库的影响,通过田间定位试验,设置枸杞单作+不施有机肥(S0)、枸杞单作+中量有机肥(2 kg·株-1,S1)、枸杞单作+高量有机肥(4 kg·株-1,S2)、枸杞/肥田萝卜复合种植+不施有机肥(M0)、枸杞/肥田萝卜复合种植+中量有机肥(2 kg·株-1,M1)和枸杞/肥田萝卜复合种植+高量有机肥(4 kg·株-1,M2)6个处理,分析土壤有机碳活性组分含量、土壤碳库管理指数及其与其他理化因子的关系,并通过结构方程模型揭示驱动碳库管理指数变化的主要因素.结果表明:与传统枸杞单作相比,枸杞/肥田萝卜复合种植0～20cm 土层土壤易氧化有机碳、水溶性有机碳,含量和微生物生物量碳显著提高了 55.3％、25.2％和79.0％,同时碳库活度、碳库活度指数和碳库管理指数也显著提高了 18.4％、26.8％和18.4％(P＜0.05).而20～40 cm 土层土壤有机碳组分及碳库管理指数变化均不显著.与未施用有机肥处理相比,中量有机肥处理0～20 cm 土层S1和M1处理的碳库活度和碳库活度指数显著提高,高量有机肥处理仅M2处理的碳库活度、碳库活度指数和碳库管理指数显著提高61.9％、59.4％和64.9％(P＜0.05).而20～40 cm 土层S1和 S2处理的碳库指数显著降低,M1和M2处理的有机碳组分和碳库管理指数变化均不显著.结构方程模型显示:有机碳、易氧化有机碳、水溶性有机碳、全氮含量和微生物生物量碳共同解释了碳库管理指数98％的变化.综上所述,宁夏旱区枸杞/覆盖作物复合种植模式能有效提升土壤活性有机碳含量,在减少有机肥施用量的情况下仍能达到土壤培肥的目的.
Effects of cropping system of Lycium barbarum L.and cover crops on soil labile organic carbon pool in an arid region of Ningxia
This study aimed to understand the effects of cover cropping and organic fertilization on soil labile organ-ic carbon pool in Goji(Lycium barbarum L.)fields in an arid region of Ningxia.There were six treatments,inclu-ding L.barbarum monocropping+no fertilization(S0),L.barbarum monocropping+medium-level organic fertili-zation(2 kg·plant-1,S1),L.barbarum monocropping+high-level organic fertilization(4 kg·plant-1,S2),L.barbarum/radish(Raphanus sativus L.)intercropping+no fertilization(M0),L.barbarum/R.sativus intercrop-ping+medium-level organic fertilization(2 kg·plant-1,M1),and L.barbarum/R.sativus intercropping+high-level organic fertilization(4 kg·plant-1,M2).We measured the contents of soil labile organic carbon fractions,carbon pool management index,and analyzed the relationships between carbon pool management index and other physicochemical factors.The main factors driving variation in carbon pool management index were identified by structural equation model.The results showed that compared with the traditional L.barbarum monocropping,L.bar-barum/R.sativus intercropping increased readily oxidizable organic carbon content,dissolved organic carbon con-tent,and microbial biomass carbon(by 55.3％,25.2％,and 79.0％,respectively),as well as in carbon lability,carbon lability index,and carbon pool management index(by 18.4％,26.8％,and 18.4％,respectively)in the 0-20 cm soil layer(P＜0.05).There were no significant changes in the contents of organic carbon fractions and carbon pool management index in the 20-40 cm soil layer.Compared with no organic fertilization,carbon lability and carbon lability index of 0-20 cm soil layer significantly increased in the S,and M,treatments with medium-lev-el organic fertilization.Under high-level organic fertilization,the carbon lability,carbon lability index,and carbon pool management index of 0-20 cm soil layer significantly increased in the M2 treatment only,by 61.9％,59.4％,and 64.9％,respectively(P＜0.05).In the 20-40 cm soil layer,the carbon pool index of S,and S2 treatments sig-nificantly decreased,with minimal changes in the contents of organic carbon fractions and carbon pool management index of M1 and M2 treatments.Results of the structural equation model showed that organic carbon content,readily oxidizable organic carbon content,dissolved organic carbon content,microbial biomass carbon,and total nitrogen content together explained 98％of the variation in carbon pool management index.Our results indicated that the in-tercropping pattern of L.barbarum and R.sativus could effectively increase soil labile organic carbon content and achieve the purpose of improving soil fertility with reduced application of organic fertilizer in the arid region of Ningxia.
cover croporganic carbon fractionlabile carbon poolcarbon pool management indexstructural equation model
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