To further improve maize technical system with full plastic-film mulching on double ridges and planting in catchment furrows ,the field experiment was conducted to determine the dynamic response of the enzyme activity and the content of N (nitrogen ) and P (phosphate ) in two soil segments (0 to 20 cm and 20 to 40 cm ) to different N and P fertil-izer application rates ,using a randomized complete block design with three replications .The results revealed that the ac-tivity of soil urease ,phosphatase and invertase as well as the content of soil available N and available P consistently fol-lowed a rapid increasing trend during the early growing period of maize .The activity of urease ,invertase and catalase and the content of available N peaked at jointing stage ,while the highest value of phosphatase activity and available P content occurred at tasselling stage .However ,the activity of various soil enzymes and the content of N and P declined during the late growing period .There existed positively significant ( P<0 .05 ) or extremely significant ( P<0 .01 ) correlations be-tween urease activity and N and P content as well as between alkaline phosphatase activity and available P content .Inver-tase activity is positively correlated to available N and P content at significant ( P<0 .05 ) level .There was no significant correlation between catalase activity and N and P content ,as well as between alkaline phosphatase activity and available N .In the arid or semiarid areas of northwest China ,the optimal fertilizer application rate for maize with full plastic-film mulching on double ridges and planting in catchment furrows was N 210 kg·hm-2 and P2O5 168 kg·hm-2 when the plant density was 6 .75 × 104 plant·hm-2 .%为进一步完善全膜双垄沟播玉米栽培技术体系，采用大田随机区组试验法，研究了不同施肥水平下全膜双垄沟播玉米土壤酶活性及氮磷养分含量的动态变化情况。结果表明：在玉米生长前期，土壤脲酶、碱性磷酸酶、蔗糖酶活性以及碱解氮、速效磷含量均呈现快速增长趋势。脲酶、蔗糖酶、过氧化氢酶活性和碱解氮含量均在拔节期达到最大值，碱性磷酸酶活性和速效磷含量在抽雄期达到最大值。在玉米生长后期，各种土壤酶活性和氮磷养分含量又呈降低趋势。土壤脲酶活性与氮磷养分含量，土壤碱性磷酸酶活性与速效磷含量均存在显著或极显著正相关关系，土壤蔗糖酶活性与氮磷养分含量也存在显著的正相关关系，而土壤过氧化氢酶活性与氮磷养分含量之间，土壤碱性磷酸酶活性与碱解氮之间无显著相关关系。西北干旱半干旱地区全膜双垄沟播玉米种植密度确定为6．75×104株·hm-2时，最佳施肥量为纯N 210 kg·hm-2、P2O5168 kg·hm-2。
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