稻棉轮作的生态经济效益与土壤改良

THE ECONOMIC OR ECOLOGICAL BENEFIT AND SOIL IMPROVEMENT UNDER RICE—COTTON ROTATION

江汉平原黄棕壤、灰潮土及其相应水稻土上的田间试验和土壤理化分析结果表明:稻棉轮作的经济效益、生态效益显著、有利于土壤环境和肥力状况的改善。与未稻棉轮作的相比,稻棉轮作的经济纯收入增加10.96%—14.50%,田间杂草和作物病害大为减少。稻棉轮作中水改旱后,土壤中非晶形铁、铝含量分别减少16.8%—8.3%,7.4%—6.6%;土壤复合体中紧结态腐殖质碳含量较多,有利于改善土壤结构状况;原土复合度、1.00—0.01 mm团聚体、总孔隙度、通气孔隙度和有效孔隙度分别增加6.92%—2.47%、15.29%、5.91%—9.96%、81.48%—52%、85.19%—220.51%;土壤速效水含量增加,迟效和无效水含量减少,比水容量在低吸力阶段增加,在高吸力阶段变小,水分释放和供应能力增强;腐殖质易矿化和可供氮组分的比重增加。而旱改水后非晶形铁量增加26.2%;有利于腐殖质的活化和游离态有机质的积累以及复合体中硫、磷、松结态腐殖质碳含量增加;表土层的1.00—0.01 mm团聚体、总孔隙度、通气孔隙、有效和无效毛管孔隙度减少,饱和导水率减少43.09%—3.56%。稻棉轮作中土壤有机质、碳、氮、磷、硫的转化、土壤微团聚体、孔隙状况、导水性、持水性、供水性的变化,既有利于旱作物生长,也有利于水稻生长。文章还就稻棉轮作的实施条件和周期进行了讨论。

The results of field experiment and siol analysis on yellow brown soils and grey fluro apuic soils and their corresponding paddy soils in Jianghan plain indicate that the economic and ecological benefit of rice-cotton rotation are remarkable and it is in favour of improvement soil enviroment and fertility conditions. In comparison with nonrice-cotton otation, the net economic income of rice-cotton rotation increased 10.96%-14.50% and the amount of weeds and incidence of crop disease dropped obviously. After the change from paddy to dryland in the rice-cotton rotation, the amount of noncrystalline Fe and Al oxides decreased 16.8%-8.3% and 7.4 %--6.6% respectively. The content of tightly combined humus C is more. which will be in favour of improving soil structure status, the complexing degree of soil, theamount of 1.00-0.01 mm microaggregate, total porosity, aeration porosity and active capillary porosity increased 6.92%--2.47%, 15.29%, 5.91%--9.96%, 81.48%--52.% and 85.19%--220.51% respectively. The content of available water increased whereas the content of sluggish available and unavailable water of soil decreased. The capacity of soil specific ater increased in the low suction range and decreased in the higher suction range, which will strengthen the release and provision ability of soil water. After the change from dryland to paddy in the rice-cotton rotation, the amount of noncrystalline iron oxides increaded 26.2%. It is in favour of the activation of humus and the accumulationof free organic matter, and increasing the ontent of S, P and loosely combined humus in soil complexes. The amount of 1.00--0.01mm microaggergate, total porosity. aeration porosity, active and nonactive capillary porosity and saturated hydraulic conductuvity of surface soil decreased. The transformation of organic matter, C, N, P, S, and the changes of microaggregate and porosity status, hydraulic conducitvity, water retention and supply property of soil under rice-cotton rotation will be in favour of crop rowth for both dryland crops and rice. In addition to these, the implement conditions and cycle of icecotton rotation sre discussed also in this paper.