旋耕配合秸秆颗粒还田对土壤物理特性的影响

Improving Farmland Soil Physical Properties by Rotary Tillage Combined with High Amount of Granulated Straw

【目的】针对黄淮烟区植烟田由于化肥投入较高、耕作频繁造成的土壤板结、通透性降低、水稳性团聚体数量下降等土壤物理性质恶化的问题,探讨通过秸秆颗粒还田与耕作方式改善土壤物理性状的可行性。【方法】采用3年田间定位试验,以旋耕+不施秸秆颗粒(RG0)为对照,设置3种秸秆颗粒用量(G1:2 250 kg·hm^(-2)、G2:4 500 kg·hm^(-2)、G3:6 750 kg·hm^(-2))与2种耕作方式(旋耕:R、深翻:T)的交互处理,分析不同处理对土壤容重、田间持水量、土壤孔隙度、土壤团聚体稳定性的影响。【结果】(1)与RG0相比,3年间RG处理易显著降低0-20 cm土层土壤容重,降幅6.7%-16.5%,而TG处理易显著降低20-40 cm土层土壤容重,降幅3.0%-9.8%,秸秆颗粒高量还田降低比率最高。(2)RG处理提升0-20 cm土层田间持水量的效果显著,其中RG3较RG0提升14.9%(2017年);增加秸秆颗粒用量提升20-40 cm土层田间持水量显著,其中RG3较RG0提升18.0%(2018年)。(3)RG3与TG3处理显著提高0-20 cm与20-40 cm土层土壤总孔隙度,最高达17.9%与14.6%(2017年),但仅RG2与RG3处理显著提高20-40 cm土层土壤毛管孔隙度。(4)RG处理在还田后期对0-20 cm土层土壤团聚体稳定性的提升作用显著;>2 mm、<0.106 mm、0.5-1 mm、0.106-0.25 mm与1-2 mm粒级团聚体是影响0-20 cm土层土壤物理性状的主要因子(Exp>66%),而0.5-1 mm与0.106-0.25 mm粒级团聚体是影响20-40 cm土层土壤物理性状的主要因子(Exp>48%)。【结论】秸秆颗粒用量6 750 kg·hm^(-2)配合旋耕处理可同时降低0-20和20-40 cm土层的土壤容重,提升持水性能与土壤团聚体稳定性,且聚类分析也表明该处理促使土壤物理特性居于一类水平,是能有效改善当地烟田土壤物理结构的可行措施。

【Objective】Aiming at the problems of soil physical properties deterioration because of the high input of chemical fertilizer and frequent cultivation,such as soil hardening,permeability reduction and water stable aggregate quantity decrease,the feasibility of improving the above soil physical properties by straw granular fertilizer and cultivation method was discussed.【Method】Three years of field experiments were carried out with rotary tillage+no straw granular fertilizer(RG0)as the control.The three kinds of straw granular fertilizer(G1:2250 kg·hm^(-2),G2:4500 kg·hm^(-2),G3:6750 kg·hm^(-2))and two tillage methods(rotary tillage:R,deep burying:T)were set,and the effects of straw granular fertilizer and tillage methods on soil bulk density,field water holding capacity,soil porosity and soil aggregate stability were studied.【Result】The results showed that:(1)Compared with RG0,RG treatment significantly reduced soil bulk density in 0-20 cm soil layer by 6.7%-16.5%,while TG treatment significantly reduced soil bulk density in 20-40 cm soil layer by 3.0%-9.8%.The decrease rate of the high amount of straw granular returning was the highest.(2)RG was more conducive to increase the field water capacity of 0-20 cm soil layer,with RG3 increasing the most significant,up to 14.9%;the amount of straw granule fertilizer significantly affected the field water capacity of 20-40 cm soil layer,and the effect of twice and three times treatment was the most significant.(3)The total porosity of 0-20 cm soil layer was significantly affected by tillage,which was increased up to 17.9%under RG3,while TG3 significantly increased it in 20-40 cm soil layer.RG2 and RG3 could significantly increase the capillary porosity of 20-40 cm soil layer during three years.(4)The stability of soil aggregates in 0-20 cm soil layer was significantly improved under RG treatment in the later stage of returning to the field.What’s more,aggregate size of>2 mm,<0.106 mm,0.5-1 mm,0.106-0.25 mm and 1-2 mm were the important components(Exp>66%)that affected the physical properties of 0-20 cm soil layer,while 0.5-1 mm and 0.106-0.25 mm particle size aggregates were the important components(Exp>48%)that affected the physical properties of 20-40 cm soil layer.【Conclusion】Treatment of RG3 reduced the soil bulk density,improved the water holding capacity,and promoted the soil aggregates stability of the two soil layers at the same time.Cluster analysis further indicated that the soil physical properties were at the first level treated by RG3.Thus,6750 kg·hm^(-2) of straw granular fertilizer combined with rotary tillage was a feasible measure to improve the physical structure of local tobacco field soil effectively,and also provided technical guidance for the utilization of crop straw.