棉 花 学 报 Cotton Science 2006，18(4)：242-247
Study on Cotton Nitrogen Recommendation Based on Soil Inorganic Nitrogen Test Abstract：The experimental area is located in Kongque Farm，Yuli County，Xinjiang. In the area the annual precipitation is 45 mm only，the annual evaporation，however，is as high as 2200 mm.The area is rich in sunshine，the sunshine duration is 3023 hours，the accumulated temperature (≥10℃) is 4200℃，and the frost-free period is 184 days. Based on field fertilizer experiment of cotton under drip irrigation in the area，cotton nitrogen diagnosis and nitrogen fertilizer recommendation with soil inorganic nitrogen quick test was studied. Results showed that drip fertilization had the significant effects on yield. The reasonable amount of nitrogen needed for getting the highest lint yield of 2728.8kg·hm-2 was 229.5kg·hm-2. By considering soil capacity to supply nitrogen，the relationship between cotton yield and soil plus fertilizer N supply capacity was established，then the optimum N supply of different soil lay was calculated by testing inorganic nitrogen concentration in different soil lay before sowing. The nitrogen needed for optimum yield of cotton were 244.8、261.9、282.7kg·hm-2 based on Nmin concentration of soil layers in 0-20cm，0-40cm and 0-60cm，respectively. Soil plus fertilizer N supply capacity in different growth stage were significantly correlated with lint cotton yield，thus the critical value for different soil lay N supply were established. Among three soil lays，0-40cm N supply had the great works to cotton yield，and the inorganic nitrogen of upper 40 cm soil can represent the soil N-supplying capacity. The concentration of inorganic nitrogen in topsoil (0-20cm) should be an available diagnosis index for nitrogen topdressing recommendation. According to the index and the critical value of N supply，the rate of nitrogen topdressing of different growth stage should be calculated.
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