Through continious experiments of conservation tillage of returning corn stalk to field in arid areas of cen- tral Gansu , study was conducted on gray relativity between corn yield and the lasting years of the tillage and soil physio- chemical properties , and regression analysis was also made of fertility factors which had high degree of correlation with soil organic matter. The results showed that 2 ~ 6 year conservation tillage could increase corn yield by 2 .63% ~ 6 .08% . The order of degree of correlation between soil physiochemical properties and yield increase is organic matter (0 .7456) > total N (0 .706) > available K (0 .6495) > available N (0 .5977) > available P (0 .5712) > pH (0 .5134) . The content of soil organic matter tended to increas with the elongation of tillage years , with an annual increase of 3 .894% . The content of organic matter had high degree of grey correlation and positive relation with available K, available P, available Zn and availabe Cu . Returning corn stalk to field , the conservation tillage helped increase the content of organic matter in soil , which had significant effect on improving soil fertility and maintaining high and stable yield of crops .%通过在甘肃中部干旱区设置的农艺农机结合持续秸秆还田保护性耕作试验,研究了玉米增产量(率)与年限的关系及与土壤理化性状的灰色关联度,并对与有机质关联度高且相关关系显著的肥力因子进行了回归分析.结果表明:秸秆还田保护性耕作2～6a的增产率为2.63%～6.08%.土壤理化性状与增产量的灰色关联序为有机质(0.7456)＞全氮(0.706)＞速效钾(0.6495)＞碱解氮(0.5977)＞速效磷(0.5712)> pH值(0.5134).土壤有机质含量随覆盖年限的延长呈三次曲线的递增趋势,年均增加3.894%.有机质与速效钾、速效磷、有效锌、有效铜灰色关联度高且存在呈显著正相关关系的函数方程,反映出土壤有机质与它们的关系密切且稳定,秸秆还田保护性耕作在归还土壤有机质的同时,也有利于提高其含量.
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