Research Of The Mechanism And Response Of High Yield Farmland Soil Structure Characteristics To Freeze In Corn Belt Of The Songliao Plain

In the Songliao plain farming area high-yield cropland (wave) and low-yield cropland (flat type)0-20cm soil as the object of study in the field of seasonal freezing and thawing process and indoor simulation test method of combining the study of the Songliao plain, the high-yield cropland soil structure on freezing response, including the effect of a deep and degree, further elucidate the high-yield cropland soil to the freezing response mechanism.The high-yield cropland of the low-yield cropland and comparative method, under freezing conditions, through the analysis of bulk density, porosity, aggregate distribution and stability, compared to three index determination and analysis of different frequencies, different water content of frozen, the high-yield cropland and cropland of the low-yield in0-20cm soil structure characteristics, the results show:(1) Alternate freezing and thawing for conservation tillage soil environment to improve the regulation of obvious effect, freezing on different structural quality of soil (including high-yield cropland and cropland of the low-yield) structure has different effects, according to the generalized soil structure index (GSSI) and soil three-phase distance structure index changes, in high-yield field cropland of the low-yield and soil GSSI were increased by4.28%and2.99%(p<0.05), STPSD were decreased by51.80%and35.82%(p<0.05), therefore, the improvement of soil freezing on osteoporosis has certain positive effect.(2) Simulation of freeze-thaw cycle, freeze-thaw cycle on high-yield field (wave) and low-yield cropland (planar) various grain drying aggregate, water stable aggregates ratio effects were significant (p<0.01), while the initial water content of less than5mm water-stable aggregate distribution ratio there is significant influence (p<0.01). The freeze-thaw cycle and antecedent soil moisture in dry wet screened aggregate and MWD and>0.25mm aggregate retention rate has significant effect (p<0.01), compared with wet screened aggregate, dry aggregates on freezing-thawing more sensitive. High-yield cropland of cropland of the low-yield in dry aggregates with different MWD significantly (p<0.01). Freezing could significantly increase the yield on the0-20cm soil average pore number, significantly reduce the low-yield cropland0-20cm soil within the average pore diameter and Feret area. Freeze thaw cycles on the low-yield cropland has remarkable influence on the pore, moisture content of high-yielding and low-yield cropland>5mm pore average number and average area of the impact of the most significant (p<0.05).(3) The different water content after freezing and thawing soil structural characteristics change with significant influence. Antecedent moisture content is high, compared to low the low moisture content of a more significant influence. Low water content of soil, pore obvious effect; but high moisture content, but from the low water content and high moisture content contrast medium revealed, moisture content is the freezing process influence high-yield cropland and cropland of the low-yield soil hole are important factors. Black soil in the Songliao plain farming area0～20cm range aggregate composition on dry sieving aggregates with>2mm particle aggregate, and water stable aggregates with<0.25mm size advantage. Moisture on dry sieving aggregate composition characteristics demonstrated the influence of homogenizing trend, and with the increase of water content, effect size ranges from large grain size gradually transition to small grade; and on water-stable aggregate composition characteristics influence is shown to have significantly reduced>0.25mm aggregate proportion trend (p<0.05), and with the increase of water content, effect size ranges from large grain size gradually transition to small grade; Integrated dry sieving aggregates and water stable aggregate PA0.25, MWD, MWSSA, D. The results of the study can not only further systematic study of black soil in the Songliao plain farming area soil quality evaluation and management to provide theoretical support and reference, and on the black soil resources utilization and protection, for grain bumper harvest in soil structure theory has important practical significance.