黄土高原旱作土壤养分含量与供给

The Nutrient Content and Nutrient Supply of Dry-farming Soil in Loess Plateau

通过对黄土高原地区旱作土壤与灌溉土壤综合考察、矿化培养实验与土壤、雨水分析，表明旱作土壤养分平均含量均低于灌溉土壤，其中有机质、全氮、碱解氦、有效磷的平均含量均属低水平，速效钾含量较高。旱作土壤可为作物利用的养分主要来源于土壤矿化、大气沉降和肥料投入。耕层土壤矿化氨量为每ｈｍ￣２７７．１～１１６．９ｋｇ。每年每ｈｍ￣２随降水进入土壤的氮量为４．５２～１０．６０ｋｇ。１９９１年黄土高原旱作土壤施用化肥总量为４７．５０×１０￣４ｔ，平均每ｈｍ￣２施入养分８４．１５ｋｇ，肥沃旱作土壤为１５３．３０ｋｇ，均低于灌溉土壤。旱作土壤施用化肥比例为Ｎ：Ｐ＿２Ｏ＿５：Ｋ＿２Ｏ＝１．０００：０．４２０：０．０３４。大力提高化肥投入量是旱作土壤农业增产的主要途径。

The field investigite,soil culture experment,soil analysis have been applied in this paper tostudies the nutrient content and nutrient supply of dry-farming soils。 The results from the studyshowed that soil nutrient average contents of the dry-farming soils has lower then of the irrigate soils。The nutrient source of dry-farming has comed from air nutrient down into soils,and soil nutrient min-eralization, and applied fertilizers。The nitrogen mineraliza of plough horizon has be 77.1～116. 9 kg。ha￣(-1).The rainfall nitrogen down into soils has be 4.52～10. 60 kg· ha￣(-1)·yr￣(-1)·Applied fertilizershas be 53.55～153.30 kg· ha￣(-1)·yr￣(-1)·The fertilizer ratio N :P_2O_5:K_2O is 1.000:0.420:0.034。