综合产量和土壤N2O排放的马铃薯施氮量分析

施氮可提高作物产量,但同时也增加温室气体N_2O的土壤排放量。研究施氮量与产量和土壤N_2O排放的关系,对保障作物产量并兼顾环境效应的农业生产实践具有重要指导意义。该研究设置N0(0)、N1(67.5 kg/hm~2)、N2(125 kg/hm~2)、N3(187.5 kg/hm~2)4个施氮水平,采用静态箱-气相色谱法对土壤N_2O排放进行田间原位测定,研究施氮量对马铃薯产量、土壤N_2O排放的影响,分析综合产量与土壤N_2O排放的合理施氮量。结果表明:施氮显著增加马铃薯产量和土壤N_2O累积排放量,较不施氮(N0)处理,N1、N2和N3处理马铃薯产量增加78.5%、93.1%和95.6%;生育期N1、N2和N3处理马铃薯土壤N_2O累积排放量分别是N0处理的2.3、4.4和6.7倍。同时,随施氮量增加,N_2O排放系数、硝态氮强度和单产N_2O排放量均显著增加。在低氮处理(N0、N1)时,土壤N_2O排放通量与土壤温度、湿度显著正相关,而在高氮水平时,土壤N_2O排放通量与土壤硝态氮含量显著正相关。施氮67.5 kg/hm~2可确保研究区马铃薯产量并有效降低土壤N_2O排放。

Analysis on N application rates considering yield and N2O emission in potato production

Agriculture soil is the important source of N2O emission. Fertilization can increase crop yield, but also can enhance emissions of greenhouse gas N2O. There is an important guiding significance to analyze the relationship between yield, soil N2O emissions under varied nitrogen levels for ensuring crop yield and reducing environment impacts. The potato is the fourth largest planting crops in the world, and China is the biggest producer. Effect of N application rates on soil N2O emission and crop yield have been intensively studied in the temperate zone with continental climate, and these studies simply focused on either yield or N2O emission, while it has never been reported in the north subtropical monsoon climate. In this study, field experiment was conducted in the Daheqiao experiment base (23°32′N, 103°13′E) of Yunnan agricultural university, in Xundian County, Yunnan province of China, from April to November in 2015. And four N application levels (unfertilized-N0, 0; low nitrogen application rate -N1, 67.5 kg/hm2; conventional nitrogen application rate-N2, 125 kg/hm2; high nitrogen application rate -N3, 187.5 kg/hm2) with three replications were compared based on potato cultivation of Huize 2. Aiming to study the effect of N application rates on potato yield and soil N2O emission at growing period, soil N2O emission was collected in situ by static chamber and analyzed using gas chronographs technique. Simultaneously, optimizing N application rates to increase yield and minimize N2O emission was analyzed. The results showed that fertilization increased the potato yield and cumulative N2O emission significantly. The soil was a source of atmospheric N2O emissions in whole potato growing season, and an obvious seasonal difference was monitored. Compared with N0, N1, N2, and N3 treatments increased by78.5%, 93.1% and 95.6% in yield. The cumulative N2O emission of N1, N2, and N3 treatments were 2.3, 4.4, and 6.7 times that of N0 treatment, respectively. The potato yield was largest when N application rates 125 kg/hm2, and no longer increased with the increasing N application rate. The first and secondary peaks of N2O emission were observed at the flourishing stage (23 May) and harvest stage (11 August), respectively. Meanwhile, N2O emission factor and yield-scaled N2O intensity significantly improved with the increase of N fertilizer. The proportion of the loss of nitrogen in the form of N2O significantly increased with the increasing N fertilizer. Nitrate intensity could effectively reflect the intensity of soil N2O emission. N2O emission flux was significantly correlated with soil temperature and humidity only at low N levels (N0, N1) .Soil NO3--N content was the key factor for N2O emission at high N levels. Comprehensive considering the average N2O emission coefficient (1%) reported by IPCC as the fertilization standard of nitrogen and potato yield in farmland ecosystem ,therefore, the reasonable N application rates were about 62.5 kg/hm2 in potato production.