| Agricultural Technology Extension Station for oriented cultivation of maize high yield and the conventional production field demonstration field is chosen as the research object. A phenomenon is studied that with different cultivation mode, high yield farmland total soil, aggregate and organic inorganic complex distribution character of organic carbon; and the relationship of the physical and chemical properties, clay mineral composition and soil organic carbon is analyzed. The relationship of Soil organic carbon and the crop yield and soil fertility is discussed and a theoretical basis for organic carbon fixation and improving soil fertility is provided.The main results are as follows:1The content of soil organic carbon decreased with layer down. The organic carbon content of high yield soil was higher than that of the control soil.2Soil particle size was classification by size of particle. The organic mineral complex in black soil was mainly fine sand, then the clay size complex and the silt complex, yielding soil clay complexes contained less than conventional production fields. Comparing shows that, silt, fine sand complex decreased rather than inorganic particles, the fine sand size complex and the clay size complex increased. High-yield soil decreases greater than the conventional control soil.The organic carbon primarily consisted in the small granule diameter of organic mineral complex. There was a accumulation tendency for organic carbon to the small granule diameter of organic mineral complex. The result after comparing with the control group soil showed that, the content of organic carbon in organic mineral complexes was higher than that of the control, and the reserves of organic carbon of clay size complex was lower than that of the control, and of silty size complex was higher.The correlation analysis showed that, there was a negative correlation among organic carbon content of the clay complex, clay complex content and inorganic clay content. Moreover, there was a significant positive correlation among organic carbon content of the powder-grain complex, powder-grain content and inorganic silt content.3Soil samples are graded according to aggregate size. By dry sieving, the composition of aggregates was mainly>10mm. By wet sieving,1-0.5mm aggregates obviously less than that of0.5-0.25mm.The content of organic carbon in aggregate decreased with layer down. The content of high yield soil organic carbon in aggregate was higher than that of the control soil by dry sieving. The content of organic carbon in1-0.5mm particle size of aggregate less than that in0.25-0.5mm by wet sieving. The small grade aggregate combine organic carbon, achieved the organic carbon fixation better.4The soil bulk density of the samples soils was increased with the increase of soil depth, high yield soil were slightly less than that of the control. Soil porosity and bulk density of the law was the opposite. The content of organic carbon increased with the density increases and increased with the porosity increases.The content of total nitrogen, total phosphorus, available nitrogen and available phosphorus presented a substantially decreased with soil layer down; The content of them of high yield soil was higher than that of the control soil. The content of total potassium and available potassium was increased first and then decreased with soil layer down. The content of total potassium of high yield soil was higher than that of the control soil. Compared with the control effective phosphorus changes of the content of available potassium was not very significant.Soil organic carbon and porosity was significantly positively correlated, a significant negative correlation with volume weight, and positively correlated with available phosphorus, total nitrogen, total phosphorus, total potassium.5. Because soil samples were collected geographical nearly, there was no obviously difference among clay mineral composition of the soil, The results of the X-ray diffraction analysis of clay showed that both for high-fat and normal paddy soil for production, clay mineral composition are type montmorillonite and illite2:1, and with a certain amount of chlorite, vermiculite, and high kaolinite as1:1. With a high cation exchange capacity, and a rich composition of inner surface, montmorillonite, illite and other2:1type clay mineral could be combined with soil organic through a variety of ways, which would enable the soil to maintain a high carbon sequestration capacity. |
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