[Effects of potassium application rate and time on the uptake and utilization of nitrogen and potassium by winter wheat].

The study with 15N tracing techniques showed that basal application of K did not increase the N and K accumulation in wheat plant when the available K content in 0-20 cm soil layer was 118.5 mg x kg(-1), but increased the accumulation significantly when the soil available K content was 79.0 mg x kg(-1). When the fertilizer K was 1/2 basal-applied and 1/2 top-dressed at elongation stage, the absorbed fertilizer N and soil N by plant as well as the residual N of top-dressed N in soil were increased with increasing K application rate, while the fertilizer N loss decreased. Compared with basal application, the split application of K increased the accumulated amount, uptake efficiency, and productive efficiency of N and K significantly. When the K application rate was 135 kg x hm(-2), split application of K promoted the absorption of top-dressed and soil N by plant, and increased the residual N of top-dressed N in soil. The results also showed that K application increased the grain yield and its protein and wet gluten contents. At the same K application rate, split application had better effect than basal application, and treatment K45 +45 (45 kg x hm(-2) as basal and 45 kg x hm(-2) top-dressed) showed the best effect. Applying excessive K tended to decrease wheat yield and its quality.