Studies On Nitrogen Efficiency And Growth Of Sugarcane Using ¹⁵N Tracer Technique

To evaluate the characteristics of nitrogen utilization and nitrogen fertilizer fate of sugarcane, a micro-plot experiments were conducted to study on the growth of sugarcane and sugar accumulating,nitrogen utilization, the fate of urea-15N in sugarcane. The main results are as follows.1.Effect of different application methods of nitrogen fertilizer in sugarcaneFate of nitrogen fertilization in field had four parts, which is plant uptake of sugarcane, residue in soil, leakage and other loss (mainly gas loss). The results showed that application methods of nitrogen had certain impact on the sugarcane. Single-dose nitrogen application make the sugarcane to have better physio-biochemical at seedling stage, but there was no obvious difference between other groups, while a decrease in all was observed at tillering and elongation stage.2.5g/pot basic fertilizer+2.5g/pot tillering fertilizer application make the sugarcane to have better physio-biochemical at tillering stage, there was no obvious difference between 1.5g/pot basic fertilizer+1.5g/pot tillering fertilizer+2.0g/pot elongation fertilizer application on yield, and had higher sugarcane juice brix, lower reducing.1.5g/pot basic fertilizer+1.5g/pot tillering fertilizer+2.0g/pot elongation fertilizer application make the sugarcane to have better physio-biochemical at elongation and maturing stage, but there was no obvious difference between other groups. the utilization rate of nitrogen of 3-time application was higher than 1-time application.2. Effect of different amount of nitrogen fertilizer in sugarcaneIn accordance with the normal nitrogen application methods, physio-biochemical and yield of 2.5g/pot were relatively poor, obvious difference between other groups, but had a better quality, sucrose content and gravity purity were higher than other. The physio-biochemical of 5g/pot nitrogen fertilizer was better than 2.5g/pot nitrogen, yield of 5g/pot nitrogen fertilizer was no obvious difference between 7.5g/pot. Quality of sugarcane was better than 7.5g/pot and poorer than 2.5g/pot, The physio-biochemical and yield of 7.5g/pot nitrogen fertilizer was better than other, but had a poor quality. The nitrogen utilization efficiency were downtrend with the amount of topdressing increased.