【摘要】 本文就苏南地区二种粘质水稻土的土壤紧实度和土块组成对水稻生长的影响进行了研究,并对不同方法耕作后耕层土块的组成状况进行了观测,结果指出:土壤紧实度和土块/细土比例的不同对水稻生长有明显的影响,土壤紧实度对水稻生长的影响是通过土壤对根的机械阻力,抑制土壤养分的转化及水分物理特性的改变所致;而土块组成的影响可能主要是影响土壤养分的转化。研磨细了的土壤转化成NH₄-N的量最高,土块大于1厘米者对NH₄-N的产生受到严重抑制,因此认为,春耕后耕层中小于1厘米的土块是评定春耕质量的一个重要指标,耕层土块大于8厘米时妨碍栽秧操作,8—4厘米者影响次之,1—4厘米者对栽秧无影响。对于要获得较小土块组成的耕作质量,旋转耕作效果最好,机耙最差,但土壤经过充分晒垡后,各种耕作方法均可获得较好的相同效果,这时,对合适机具的选择主要可从经济效益考虑。渍水条件下土垡经过挤压受损后,可使土块膨软,这或对土壤养分的释放有利,故一般用于春耕机具,只考虑其切割效果而不同时考虑挤压作用是不足的。更多还原

【Abstract】 The effect of soil compaction and clod distribution of two clayey soils on the growth of rice in southern Jiangsu province was studied. The distribution of soil clods in the plough layer under different ploughing methods was also investigated. The results obtained denoted that the compaction and the proportion of soil clod and fine soil particles influenced the growth of rice markedly.The effect of soil compaction on the growth of rice was produced by the mechanical resistance of soil to the penetration of roots, the inhibition of nutrient transformation and the unfavorable physical properties of soil moisture. The mineralization of soil nutrients might be mainly affected by soil clodding.Grinding the soil in water might promote the release of NH₄-N. The release of NH₄-N was obviously less in clod>1 cm in diameter. Therefore, it is suggested that the quantity of soil clod<1 cm in diameter in the plough layer may be taken as an important index for the evaluation of spring ploughing.更多还原