有机物料深混还田对棕壤孔隙结构及玉米产量的影响

Inversion tillage with organic materials incorporation affects soil pore structure and maize yield in a Hapli-Udic Cambisol

土壤孔隙结构在土壤水分和物质运移过程中起着重要作用,开展不同耕作方式和有机物料还田下土壤孔隙结构研究,可为耕地质量评价提供理论依据。本研究于2018年开始,以辽宁南部棕壤为研究对象,以常规耕作(T15)为对照,分析了秸秆浅混还田(0~15 cm)(T15+S)、秸秆深混还田(0~35 cm)(T35+S)和秸秆有机肥配施深混还田(0~35 cm)(T35+SM)对土壤孔隙结构的影响。采集0~15 cm和15~35 cm土层原状土柱,采用CT扫描和图像分析技术,量化土壤孔隙参数,包括孔隙分布特征、>31μm孔隙总数、>31μm孔隙度、成圆率、欧拉数、各向异性和分形维数。结果表明,T35+S和T35+SM处理较T15处理田间持水量显著增加(P<0.05)。与T15处理相比,0~15 cm土层T15+S、T35+S和T35+SM处理>31μm孔隙总数分别显著降低了15.2%、54.4%和60.5%(P<0.05),>31μm孔隙度分别显著降低了26.9%、39.7%和55.1%(P<0.05),不同孔径孔隙数量也表现出显著降低。而在15~35 cm土层T35+S和T35+SM处理>31μm孔隙总数、孔隙度和不同孔径孔隙数量均较T15处理增加。有机物料深混还田改善了上下土层孔隙连通度,促使孔隙形状趋于规则,表现为与T15+S和T15处理相比,0~15 cm和15~35 cm土层下T35+S和T35+SM处理各向异性和欧拉数均显著降低(P<0.05)。与T15处理相比,不同处理玉米产量均显著增加,其中T35+SM处理最高,增产了10.4%(P<0.05)。0~15 cm土层>31μm孔隙总数、孔隙度和500~1000μm孔隙数量与产量相关性最大,分别达到了28.0%、32.2%和27.1%;15~35 cm土层500~1000μm孔隙数量与产量的相关性最大,达到了29.0%。因此,有机物料深混还田可改善土壤孔隙结构,增加土壤保水供水能力,提高了该地区农业生产能力,是较为理想的棕壤地力培育途径。

Soil pore structure plays an important role in the process of soil water and mass transport,and research on soil pore structure under different tillage and organic material return may provide a theoretical basis for optimizing tillage methods.We conducted a field experiment starting in 2018 in a region of northeastern China with Hapli-Udic Cambisol using four treatments:conventional tillage(0−15 cm)without or with maize straw return(T15 and T15+S),inversion tillage(0−35 cm)with straw return(T35+S),inversion tillage(0−35 cm)with cattle manure plus maize straw(T35+SM).Synchrotron radiation CT scanning and digital image analysis technology were used to analyze undisturbed soil columns in 0−15 cm and 15−35 cm soil layers after maize harvest to quantify soil pore parameters,including pore distribution characteristics,total>31μm pore number,>31μm porosity,circularity,Euler number,anisotropy and fractal dimension.The field water capacity was significantly higher in T35+S and T35+SM than that in T15.Compared with T15,the total number of>31μm pores in 0−15 cm soil layer decreased by 15.2%,54.4%and 60.5%,respectively(P<0.05),and>31μm porosity decreased by 26.9%,39.7%and 55.1%,respectively(P<0.05).The number of pores of different particle sizes also decreased significantly in T15+S,T35+S and T35+SM than in T15 in 0−15 cm soil layer.But the opposite trends were observed in T35+S and T35+SM in the 15−35 cm soil layer.Inversion tillage with organic materials incorporation improved topsoil and subsoil pore connectivity and promoted the regularity of pore shape.The anisotropy and Euler number in 0−15 cm and 15−35 cm soil layer decreased significantly in T35+S and T35+SM than T15+S and T15.The maize yield in T15+S,T35+S and T35+SM was significantly higher than that in T15,with T35+SM being the highest.Total>31μm pore number,>31μm porosity and 500−1000μm pore number in the 0−15 cm soil layer were the most correlated with yield with 28.0%,32.2%and 27.1%,respectively,while<500μm pore number in the 15−35 cm soil layer was the most correlated with yield with 29.0%(P<0.05).Therefore,inversion tillage with organic materials is a more effective way to improve soil fertility,which may enhance agricultural productivity by improving soil pore structure.