摘要： 1994～1995年对旱地玉米不同耕作系统土壤磷、钾进行了研究，并对6年的玉米产量作了简要分析，结果表明，在6年的试验地上，免耕覆盖后，0～20cm土层速效磷比常规耕作玉米种植区平均低63.88%,加大磷肥用量是免耕覆盖持续高产的关键措施之一。土壤速效钾玉米种植区免耕覆盖0～20cm土层比常规耕作平均高25.64%,20～50cm土层基本无差异。速效钾的增加既是高产的基出，也是提高作物抗旱性的重要因素。休闲地的变化趋势与玉米田基本一致。随着免耕年限的增加，增产幅度减小，周期以3～4年为宜。

关键词: 免耕, 覆盖, 土壤养分, 免耕周期

Abstract: A study was conducted during 1994～1995 in dryland corn field to determine the changes of soil phosphorus,potasium and corn yield under four tillage systems.The four tillage systems included no tillage with whole stalk mulch, mulch with whole stalk after full plow, conventional tillage and plough under the stalk after the harvest. Results indicated that:compared with coventional tillage, soil Olsen P decreased by 63 88% at 0～20 cm depth， exchangeable K increased by 25 6% at 0～20cm depth;and no difference was found between no tillage and coventional tillage at 20～50 cm depth. The period of no tillage was 3～4 years.

Key words: No tillage, Mulch, Soil nutrient, Period of no tillage

中图分类号: 

• S345