Study on index of fertilizer recommendation for spring wheat in Hetao irrigated area

To establish index of fertilizer recommendation for Spring wheat in Hetao Irrigated Area, a total of 141 fertilizer trials designed as 3414 were carried out on irrigated Spring wheat based on soil fertility in Hetao irrigated area. The results showed that agronomy efficiency of N, P2O5 and K2O on Spring wheat in Hetao irrigation area was 64, 60 and 54 kg/kg respectively. Contrbution of N, P2O5 and K2O to Spring wheat yield was 252%-409% with mean of 335%, 159%-211% with mean of 184%, and 72%-90% with mean of 80% respectively, with yield increasing effect of N＞P2O5 ＞K2O. Yeild response by fertilizer application increased with the declining of soil fertility, while agronomic efficiency decreased. The indices of sufficiency and deficiency of soil nutrients in Hetao irrigation area were built according to the relation of soil nutrient and relative yield. Total N was divided into five levels: lower（063 g/kg）, low（063-085 g/kg）, medium （085-115 g/kg）, high（115-156 g/kg）, higher（＞156 g/kg）. OlsenP into: lower （59 mg/kg）, low（59-118 mg/kg）, medium（118-238 mg/kg）, high（238-480 mg/kg）, higher（＞480 mg/kg）. Available K: lower（906 mg/kg）, low（906-1291 mg/kg）, medium（1291-184 mg/kg）, high（184-262 mg/kg）, higher（＞262 mg/kg）. Fertilizer N, P and K recommendation models for Spring wheat in Hetao irrigated area were established according to the relationship of optimal application of N, P2O5 and K2O and soil nutrients. Index of fertilizer recommendation for Spring wheat in Inner Mongolia Hetao irrigated area was constructed primarily.