Effect Of Nitrogen Application Patterns On Nitrogen Use Efficiency And Fertilizer Fate Of Winter-planting Potato In Guangxi

A field experiment and a micro-plot experiment were conducted with early-maturing potato variety’Favorita’. Commodity urea (N46.4%) was used in the field experiment and 15N labeled urea (abundance ratio10.15%,N46.4%) was used in the micro-plot experiment. Equal amount nitrogen fertilizer of 160kg N/ha was applied in both experiments. Each experiment was designed with three nitrogen application patterns and a control. They were:treatment 1(T1),100%nitrogen fertilizer was single basal application; treatment 2(T2), nitrogen fertilizer was split into two portions of 55%basal application and 45%seedling fertilizer; treatment 3(T3), nitrogen fertilizer was split into three portions of 55%basal application and 30%seedling fertilizer and 15%squaring stage fertilizer; control (CK), no nitrogen fertilizer was applied. To study the effect of nitrogen fertilizer application patterns on physiology, growth, nutrition, N use efficiency, the fate of nitrogen, the yield and quality of tuber of winter-planting potato in Guangxi. This thesis comes to the following conclusions:1、Effects of nitrogen application patterns on potato growth, physiology, nutritional statusNitrogen application patterns affected the emergence of potato. Emergence of potato delayed significantly as the amount of basal application increased, but the difference of dry weight of potato among three nitrogen application patterns wasn’t significant; Nitrogen fertilizer application for once(T1) had the most effect on improving the content of chlorophyll, the content of soluble sugar, the activities of nitrate reductase, the root activity and the NPK accumulation at the middle stage; Nitrogen fertilizer application for 3 times(T3) had to the most effect on improving the content of soluble protein, and the NPK accumulation of the latter growth stage.2、Effects of nitrogen application patterns on nitrogen use efficiency for PotatoNitrogen application patterns had significant effect on total nitrogen use efficiency, and the nitrogen use efficiency in order among the nitrogen application patterns was T3>T1>T2,T3 and T1 had no significant difference, significantly higher than T2. And then nitrogen application patterns could influence significantly on nitrogen absorption of tuber. Compared to T1 and T2, T3’s fertilizer nitrogen use efficiency of tuber was highest (30.94%), which was 28.62% and 27.15% higher than T1 and T2 respectively.3、Effects of nitrogen application patterns on nitrogen fateNitrogen application patterns had significant effect on nitrogen fertilizer residual in 0～15 cm soil layer. The amount of nitrogen fertilizer residual of T3 was 72.14 kg/ha, which was the highest and increased by 15.61%,7.03% comparing with T1 and T2. Nitrogen fertilizer losses of T3 was 13.17 kg/ha, which was significantly lower than T2(23.54 kg/ha) and T3(24.81 kg/ha).4、Effects of nitrogen application patterns on yield and quality of potatoNitrogen application can significantly increase the potato yield. Yield of T1,T2 and T3 was 27.1 t/ha,25.1 t/ha and 27.0 t/ha, which was 46.43%,36.03% and 46.09% higher than CK, respectively. Nitrogen application decreased the content of soluble sugar and starch, increased the crude protein content. Nitrogen application patterns had no significantly effect on yield and quality of tuber.5、Effects of nitrogen application methods on the N balance of potato fieldNitrogen application could increase the available and total nitrogen content in 0～15 cm,15-30 cm and 30-45 cm soil of post-harvest. The available and total nitrogen content in 0-15 cm of post-harvest were increased by 10.76%-13.60%and 2.12%-4.70%, comparing with that of pre-plant. The increase in order among the nitrogen application patterns was T3>T2>T1, it was T1>T2>T3 in 15-30 cm soil layer, but nitrogen application or patterns had little effect on the available and total nitrogen content.