不同水肥处理对莴笋土壤速效养分及水分利用效率的影响

摘要

A field experiment was conducted to study the effects of different moisture conditions (75%, 65%,55% lower irrigation limits)and fertilizing amount (national fertilizing amount,85% national fertili-zing amount,70% national fertilizing amount)on the roots zone soil available nutrient contents and WUE of asparagus lettuce (Lactuca sativa var.angustana Irish).The results showed that high fertilizing amount was better for dry matter accumulating of overground and underground parts during seedling stage.While in the mature period,the root dry weight of no fertilizing is the maximum,the overground parts dry weight reached the maximum under medium water and medium fertilization treatment (W2 F2 ).Under same water and fertilizer treatments,soil available N changed gradually,available P raised firstly,then declined,but a-vailable K reduced sustained with the development of growth period.And under different water and fertiliz-er treatments,medium water and high fertilization treatment (W2 F1 )improved soil ability of supplying N, K,P residual quantity was low in soil.The WUE decreased along with fertilizing amount reducing,but when the lower irrigation limits dropped,it showed raising firstly,and then falling.WUE of medium water and high fertilization amount treatment (W2 F1 )was 30.41kg/m3,it is the highest.It is suggested that me-dium water and high fertilization amount combination treatment (W2 F1 ),as fertilizing amount N:296.7 kg/hm2 ,P2 O5:70.2 kg/hm2 ,K2 O:171.6 kg/hm2 ,total irrigation amount 2820.15 m3/hm2 are the optimum for asparagus lettuce growth and development in Hexi area of Gansu Province.%采用大田试验方法,研究了不同水分(75%、65%、55%灌水下限)和不同施肥量(当地施肥量、85%当地施肥量、70%当地施肥量)对春茬莴笋根际土壤速效养分含量和水分利用效率的影响.结果表明：高施肥量有利于莴笋苗期地上部和地下部干物质的积累；在成熟期不施肥的处理根干质量最大,中水中肥处理(W2 F2)的地上部干质量最大；同一水肥处理下,随着莴笋生育期的推进,土壤碱解氮变化趋势平缓,有效磷含量先上升后下降,速效钾则呈现持续下降趋势,不同水肥处理中,中水高肥处理(W2 F1)提高了土壤对氮、钾的供应能力,土壤中磷残留量较低；水分利用效率随着施肥量的减少下降,随着灌水下限的下降先升高后下降,中水高肥处理(W2 F1)的水分利用效率最高,为30.41 kg/m3.综合评价,中水高肥(W2 F1),即施 N 296.7 kg/hm2、P2 O570.2 kg/hm2、K2 O 171.6 kg/hm2,全生育期灌水定额为2820.15 m3/hm2的灌水施肥组合对甘肃省河西地区莴笋的生长发育最有利.