| Straw was deeply and concentratedly returned to field after harvest in fall by a turnover plow to furrow method. Based on this, the resulting effects over a two-year term on soil main physical and chemical properties and corn root system were investigated. The results indicated that with the increment of straw returned, the bulk density in each soil layer was reduced by 2.42%～10.67% and the water content of soil became increased by 3.99%～14.68%, compared with the control treatment. The contents of soil organic carbon and total nitrogen were significantly improved by 4.34%～97.97% and 1.53%～44.36%, respectively. The length, surface area, volume and average diameter of corn root system were all greater than the control treatment, reaching the most significant level with 12 000 kg·hm-2 treatment. In conclusion, straw deep returning had obvious effects on reducing soil bulk density, increasing water content, soil organic carbon and total nitrogen, and promoting corn root growth. |