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(二)坚持用地养地相结合,不断提高棉田土壤肥力。据近几年部分重点产棉县测定,棉田肥力均有不同程度的下降。在南方两熟制棉区,棉田前作中豆科绿肥养地作物面积大幅度缩减,直接导致了棉田肥力的下降。如浙江省慈溪县过去棉田麦肥间作面积60多万亩,现在只有30多万亩;湖北省天门县1966年冬绿肥54万亩,现在只有2—3万亩,蚕豆面积过去40多万亩,现在减少到2—3万亩。有些地方,过去豆科作物占相当比例,棉田肥力曾有提高,发展粮棉间作后挤掉了豆科作物,引起土壤肥力下降。如江苏省启东县过去夏粮是半麦半豆,秋季是半粮半棉,两年四熟轮作,豆科绿肥面积保持占地60%,因而使棉田地力不断提高,
(B) adhere to the combination of land-use, and continuously improve the cotton soil fertility. According to the determination of some key cotton producing counties in recent years, the fertility of cotton fields has decreased in varying degrees. In the southern two-cropping cotton area, cotton cropland before the green legumes fertilizer crop area significantly reduced, a direct result of decline in fertility of cotton. For example, in the past, more than 600,000 mu of wheat-wheat intercropping area was cultivated in Cixi County, Zhejiang Province, and now it has only 300,000 mu. In Tianmen County, Hubei Province, there are 54,000 mu of green manure in 1966, with only 2-3 million mu of land and over 40 mu of broad bean area , Now reduced to 2-3 million mu. In some places, in the past, leguminous crops accounted for a considerable proportion of cotton fertility had increased, the development of grain and cotton intercropping squeezed leguminous crops, causing decline in soil fertility. For example, in Qidong County, Jiangsu Province, past summer grains were semi-wheat and semi-bean, while in autumn, half-grain and half-cotton were planted. Four-crop rotation was carried out in two years. The area of legume green manures was kept at 60% of the total land area,