Effect of replacing synthetic nitrogen fertilizer with animal manure on grain yield and nitrogen use efficiency in China: a meta‐analysis

Abstract

To reduce reliance on synthetic nitrogen (N) fertilizer and sustain food production, replacing synthetic N fertilizer with animal manure as an effective method is widely used. However, the effects of replacing synthetic N fertilizer with animal manure on crop yield and nitrogen use efficiency (NUE) remain uncertain under varying fertilization management practices, climate conditions, and soil properties. Here, we performed a meta-analysis of wheat (Triticum aestivum L.), maize (Zea mays L.), and rice (Oryza sativa L.) based on 118 published studies conducted in China. Overall, the results indicated that substituting synthetic N fertilizer with manure increased yield by 3.3%−3.9% for the three grain crops and increased NUE by 6.3%−10.0%. Crop yields and NUE did not significantly increase at a low N application rate (≤120 kg ha−1) or high substitution rate (>60%). Yields and NUE values had higher increases for upland crops (wheat and maize) in temperate monsoon climate/temperate continental climate regions with less average annual rainfall (AAR) and lower mean annual temperature (MAT), while rice had higher increases in subtropical monsoon climate regions with more AAR and higher MAT. The effect of manure substitution was better in soil with low organic matter and available phosphorus. Our study shows that the optimal substitution rate was 44% and the total N fertilizer input cannot be less than 161 kg ha−1 when substituting synthetic N fertilizer with manure. Moreover, site‐specific conditions should also be considered.

N Utilization, Residual and Loss Characteristics of Spring-Topdressing (15N-urea) Pear Orchards in the Old Course of the Yellow River Area

“…Soil and plant total N were determined by micro-Kjeldahl method [25]. The liquid that remained after determining total N was concentrated by heating in a water bath with a few drops of dilute sulfuric acid for 15 N determination. 15 N abundance was determined by isoprime100 stable isotope ratio mass spectrometer, and soil bulk density was determined by the ring knife method.…”

“…The labeled urea has the same chemical formula and chemical properties as the common urea. After mixing and watering, ordinary urea and 15 N-urea were absorbed by the tree with the same probability. Therefore, the absorption and utilization of 15 N urea can reflect the absorption and utilization of ordinary urea.…”

“…Studies have shown that soil organic matter content and pH can affect ammonia volatilization and nitrification and denitrification in soil, which in turn affects soil N retention and loss [11][12][13][14]. In addition, Ren et al found that different climate types have an impact on the N utilization efficiency of chemical fertilizers and organic fertilizers, which is manifested as temperate continental climate zone > temperate monsoon climate zone > subtropical monsoon climate zone [15]. Under the same soil fertility, Liu et al found that the yield and N utilization efficiency of wheat in Fujian were significantly lower than those in Sichuan.…”

“…The N competition ability of different growth centers was significantly affected by climate, fertilization and tree growth potential. The distribution of 15 N reflects the nutrient competition of organs in different periods of the tree. The fertilization plan formulated according to the requirements of trees at different periods can effectively reduce the application of N fertilizer and improve utilization rate.…”

“…We hypothesized that N absorption and distribution of pear trees in different phenological periods and N loss of fertilizer are different in different areas. In this study, we used 15 N fertilizer to label early-maturing sand pears. The results of experiment do not concern the utilization of nitrogen from fertilizers in the form of urea but N originated from the small doses of nitrogen in the form of labeled urea.…”