一、前言国营灵武农场是盐演化地区,几年来通过生产实践证明排水条件下种植水稻能有效的改良盐土,进而种植旱作,但土地长期浸水造成土壤肥力的降低,种植旱作物必须施用大量肥料,以1956年每亩施120斤油渣计需7.02元,以每亩收300斤计,肥料的投资就占生产品收益的 I. Introduction State-owned Lingwu Farm is a salt-evolving area. Over the past few years, it has been proved through production practice that planting rice under drainage conditions can effectively improve salt so as to plant dry farming. However, long-term soaking of land causes reduction of soil fertility and planting of dry crops must be applied A large number of fertilizers, with 19 pounds of fertilizer per mu in 1956, accounting for 7.02 yuan to 7.02 yuan to 300 kg per mu dollars, the investment in fertilizer accounted for the proceeds of the product