渭河上游渭北干旱区红土质修筑梯田,大量熟化土层被用作培埂(生土培不成埂子),而熟化度差的土层里,有机质、氮、磷的含量极少(分别为0.4—0.6％;0.034—0.04％;0.08—0.11％);土壤的毛管孔隙小,总孔隙度大;土壤的持水力差,吞吐量小。因此,新修梯田具有生、干、硬、凉、薄等特点,产量上不去。一块一九七○年修的梯田,到一九七 Weibei arid area Weibei arid area terraces, a large number of matured soil is used as a peat (raw soil cultivated into razor clam), and poor soil maturity, organic matter, nitrogen, phosphorus content is very small 0.4-0.6%; 0.034-0.04%; 0.08-0.11%). The capillary pores of soil are small and the total porosity is large. The soil has poor water holding capacity and small throughput. Therefore, the newly built terraces with health, dry, hard, cool, thin and so on, yield does not increase. A 1970’s terraced fields until 1979