【Objective】 Combined chemical fertilizers with manure is one of the important approaches to improve the nitrogen use efficiency (NUE) of crops. Nowadays, rare studies focused on systematic comparison and analysis of combine chemical fertilizers with manure on nitrogen use efficiency in different regions of China. In addition, NUE is affected by many factors, such as nitrogen application amount, soil properties and the climatic conditions and even most of them are in the specific regions. Therefore, this study was carried out to explore the effects of chemical fertilizers combined with manure on NUE, and quantify the response of NUE to manure application in different soils and climatic regions, so as to give the guidance on sustaining regional agricultural development and provide an important theoretical basis for reducing fertilizer application. 【Method】 This study was conducted based on a database of NUE including 412 sets on NPKM vs. NPK, which were collected from 110 published articles with wheat, maize and rice. We analyzed the differences of NUE between the treatment of NPK and NPKM in five regions in China by Meta-analysis, and quantified the contribution of main controlling factors on positive manure affects by Random Forest analysis. 【Result】 Compared with NPK, NPKM treatment increased the NUE by 3.6%. NPKM treatment significantly increased the NUE of crops in all regions except the Northeast China. The highest enhancement was found at Northwestern China, followed by Northern China, Southern Region and Eastern China. Soil organic matter, pH, available potassium and total nitrogen were the main factors affecting the “positive effect” of manure on NUE. The increment of NUE by manure application was higher in the soils with lower organic matter content than that in the soils with high organic matter content. The increase of NUE in alkaline soils with manure applied was 1.3 and 1.8 times higher than those on neutral and acidic soils, respectively. The improvement of NUE by manure application varied among climate regions: temperate continental climate zone>temperate monsoon climate zone>subtropical monsoon climate zone. 【Conclusion】 The application of manure could significantly increase the NUE of crops, especially in northwestern areas with low organic matter content and less rainfall. 相似文献
Understanding the soil nitrogen (N) mineralization potential (N0) and crop N availability during the growing season is essential for improving nitrogen use efficiency (NUE) and preventing over-fertilization, which lead to negative environmental impacts.
Methods
Five black soils with different levels of fertility were selected in Northeast China. The N0 and kinetics of these soils were estimated through laboratory experiments at different incubation temperatures (15, 25, and 35 °C). N mineralization dynamics were simulated using field soil temperature according to the incubation results. Moreover, the N uptake dynamics of maize were simulated according to the literature.
Results
Compared with the very low-fertility soils, the cumulative mineralized nitrogen increased under all incubation temperatures (15, 25, and 35 °C), by 48–136%, 8–61%, and 24–59%, respectively, in the medium- and high-fertility soils. The highest N0 values (96.90, 115.31, and 121.33 mg/kg at the three different temperatures) were recorded in the very high-fertility soils. The soil N mineralization dynamics and N uptake of maize in the growing season were highly consistent over time, although the soil N supply could not meet the maize growth requirements. The higher the soil fertility, the lower the N fertilizer requirement.
Conclusions
Different fertilizer strategies were developed based on the cumulative mineralized N, N uptake by maize, and NUE in soils with different fertility levels. We suggested a reduction of 50–65 kg N/ha in N fertilizer in the two highest fertility soils. This study provided basic data to reduce chemical N fertilizer to improve NUE and reduce negative environmental impacts.
In order to restore a degraded alkaline grassland, the local government implemented a large restoration project using fences in Changling county, Jilin province, China, in 2000. Grazing was excluded from the protected area, whereas the grazed area was continuously grazed at 8.5 dry sheep equivalent(DSE)/hm2. In the current research, soil and plant samples were taken from grazed and fenced areas to examine changes in vegetation and soil properties in 2005, 2006 and 2008. Results showed that vegetation characteristics and soil properties improved significantly in the fenced area compared with the grazed area. In the protected area the vegetation cover, height and above- and belowground biomass increased significantly. Soil pH, electrical conductivity and bulk density decreased significantly, but soil organic carbon and total nitrogen concentration increased greatly in the protected area. By comparing the vegetation and soil characteristics with pre-degraded grassland, we found that vegetation can recover 6 years after fencing, and soil pH can be restored 8 years after fencing. However, the restoration of soil organic carbon, total nitrogen and total phosphorus concentrations needed 16, 30 and 19 years, respectively. It is recommended that the stocking rate should be reduced to 1/3 of the current carrying capacity, or that a grazing regime of 1-year of grazing followed by a 2-year rest is adopted to sustain the current status of vegetation and soil resources. However, if N fertilizer is applied, the rest period could be shortened, depending on the rate of application. 相似文献