减氮覆膜下旱地麦田土壤团聚体中各物理组分的变化

Changes in Physical Fractions within Soil Aggregates Under Nitrogen Reduction and Film Mulching Measures in Dryland Wheat Field

分析覆膜条件下晋南旱塬土壤团聚体中各物理组分的变化,对于协同提高该区域土壤肥力及作物产能意义重大.依托山西省洪洞县长期定位试验基地,采集7 a的0~20 cm土层原状土壤样品,分析农户施肥(FP)、测控施肥(MF)、测控施肥+垄膜沟播(RF)和测控施肥+平膜穴播(FH)这4个处理对小麦籽粒年均产量、土壤有机碳(SOC)含量和团聚体中各物理组分[未受保护的大团聚体中粗颗粒有机碳(M-cPOC)及细颗粒有机碳(M-fPOC)、受物理保护的大团聚体中微团聚体内颗粒有机碳(M-iPOC)、受(生物)化学保护的大团聚体中矿质结合态有机碳(M-MOC)、未受保护的微团聚体中细颗粒有机碳(m-fPOC)、受物理保护的微团聚体中颗粒有机碳(m-iPOC)、受(生物)化学保护的微团聚体中矿质结合态有机碳(m-MOC)]分布比例及其有机碳含量的影响.结果表明,同FP处理相比,MF处理虽然显著降低了SOC含量,但是还能维持小麦籽粒产量,RF和FH处理协同提升了土壤肥力和作物产能,且以FH处理效果更佳,SOC含量和小麦籽粒产量分别提高了8.44%和48.86%.MF处理显著降低了M-cPOC含量,RF处理显著提高了M-iPOC含量,FH处理显著提高了M-fPOC、M-iPOC、M-MOC和m-iPOC含量,增幅分别为64.00%、98.39%、6.16%和17.48%.此外,结合冗余分析发现M-iPOC组分对提高SOC含量和小麦籽粒产量起主要作用,贡献率高达61.5%.因此,晋南旱塬区大团聚体对土壤肥力和作物产能的贡献高于微团聚体,平膜穴播通过提高M-iPOC含量,进而协同增加了土壤有机碳固存和小麦籽粒产量,可以在该区域乃至全国农作旱区推广该项栽培技术.

We studied the changes in various physical fractions within aggregates in the arid plateau of southern Shanxi Province,which has great significance for synergistically improving soil fertility and crop productivity in this region.Bulk soil samples were collected from 0-20 cm layers during a 7-year long-term experiment in Hongtong County,Shanxi Province.Wheat grain yields,SOC concentrations,proportions,and OC contents within soil aggregates were analyzed.OC contents included:unprotected coarse particulate organic carbon within macroaggregate(M-cPOC)and fine particulate organic carbon within macroaggregate(M-fPOC),physically protected intra-aggregate particulate organic carbon within macroaggregate(M-iPOC),chemically/biochemically protected mineral organic carbon within macroaggregate(M-MOC),unprotected fine particulate organic carbon within microaggregate(m-fPOC),physically protected intra-aggregate particulate organic carbon within microaggregate(m-iPOC),and chemically/biochemically protected mineral organic carbon within microaggregate(m-MOC).The treatments were①farmer fertilization(FP),②nitrogen reduction monitoring and control fertilization(MF),③nitrogen reduction monitoring and control fertilization plus ridge film and furrow sowing(RF),and④nitrogen reduction monitoring and control fertilization plus flat film hole sowing(RF).The results showed that compared with that in the FP treatment,MF reduced SOC concentration while maintaining wheat grain yield,RF and FH synergistically improved soil fertility and crop yield,especially for the FH with SOC concentration,and wheat grain yield increased by 8.44%and 48.86%,respectively.MF significantly reduced the content of M-cPOC,RF significantly increased the content of M-iPOC,and FH significantly increased the contents of M-fPOC,M-iPOC,M-MOC,and m-iPOC by 64.00%,98.39%,6.16%,and 17.48%,respectively.In addition,combined with redundancy analysis,we found that the M-iPOC fraction played a major role in increasing SOC concentration and wheat grain yield,with a contribution rate of 61.5%.Therefore,the contribution of macroaggregates to soil fertility and crop productivity was higher than that of microaggregates in the arid plateau area of southern Shanxi,and flat film hole sowing could increase the content of M-iPOC,thereby synergistically increasing SOC sequestration and wheat grain yield,which could promote this cultivation technology in the region and even in the country's arid agricultural areas.