深松结合秸秆还田对黑土孔隙结构的影响

【目的】东北黑土实施深松结合秸秆还田对土壤孔隙结构影响的研究缺乏明确性结论，为此开展本研究，旨在研究深松结合秸秆还田对黑土结构的影响机制，为合理耕层创建提供科学依据。【方法】利用在东北典型黑土区——黑龙江省绥化市青冈县开展的5年田间定位试验为平台，设置农民常规耕作（FP）、单独深松25 cm(T2)、深松25 cm结合秸秆还田（T3）和深松35 cm结合秸秆还田（T4）等处理，采用CT扫描技术开展土壤孔隙结构可视化和定量化研究，并结合田间持水量和容重等指标，探究深松结合秸秆还田对黑土孔隙结构的影响。【结果】通过土壤孔隙二维和三维图像可以清晰看出，各处理0—20 cm土层孔隙分布均明显少于20—40 cm土层，深松结合秸秆还田（T3、T4）的孔隙分布明显多于FP，增加了结构更为复杂的大孔隙。定量化分析表明，相较于FP，单独深松25 cm(T2)显著提高20—30 cm土层总孔隙度103.0%(P<0.05)，主要通过显著提高小孔隙（孔隙直径d≤0.50 mm）孔隙度91.3%和中孔隙（0.50 mm

Effect of Subsoiling Combined with Straw Returning Measure on Pore Structure of Black Soil

【Objective】The effect of subsoiling combined with straw returning on soil pore structure of black soil in Northeast China is lack of definite judgment. Aimed at such problem, this research was conducted in order to provide scientific basis for the influence mechanism of this measure on soil structure of black soil and the establishment of reasonable tillage.【Method】In this study, a 5-year field positioning experiment conducted in Qinggang County, Suihua City, Heilongjiang Province, a typical black soil area in Northeast China was used as a platform. Farmers’ conventional treatment (FP), 25 cm subsoiling alone treatment (T2), 25 cm subsoiling combined with straw returning treatment (T3) and 35 cm subsoiling combined with straw returning treatment (T4) were set. The visualization and quantification of soil pore structure were studied using CT scanning technology, and combined with field capacity and bulk density to explore the effect of subsoiling combined with straw returning on the pore structure of black soil. 【Result】The results showed that the two-dimensional and three-dimensional images of soil pores clearly showed that the pore distribution at 0-20 cm soil layer was significantly less than that at 20-40 cm soil layer in all treatments, while the pore distribution of suboiling combined with straw returning treatment (T3 and T4) was significantly higher than that under FP treatment, and their macropores with more complex structure were increased. Quantitative analysis showed that compared with FP treatment, the total porosity of 20-30 cm soil layer under T2 was significantly increased by 103.0% (P<0.05), which was achieved by significantly increasing the micropores porosity(pore diameter d≤0.50 mm) by 91.3% and mesopores porosity (0.50 mmP<0.05). While subsowing combined with straw returning treatments (T3 and T4) significantly increased the total porosity of 0-30 cm soil layer by 109.8%-382.7% (P<0.05), which was achieved by significantly increasing the macropores porosity (d>1.00 mm) by 221.5%-661.7% and the mesopores porosity by 105.4%-544.9% (P<0.05). In addition, compared with FP treatment, subsoiling combined with straw returning (T3 and T4) significantly increased the fractal dimension of soil pores at 0-30cm soil layer by 9.9%-17.7% (P<0.05), decreased the Euler number by 32.4%-66.4% (P<0.05), and significantly increased the field water capacity by 24.2%-40.6% (P<0.05). Further analysis showed that the different pore size porosity and total porosity was significantly positively correlated with field capacity and fractal dimension, but significantly negatively correlated with Euler number (P<0.01). 【Conclusion】Subsoiling combined with straw returning could improve porosity of macropores and mesopores pore of black soil, improve pore structure and connectivity, and increase field capacity, especially the effect of 35 cm subsoiling combined with straw returning treatment is the most significant, which could be recommended measure for rational tillage construction in black soil of Northeast China.