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Acta Prataculturae Sinica ›› 2022, Vol. 31 ›› Issue (9): 36-49.DOI: 10.11686/cyxb2022127

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Effects of nitrogen application on alfalfa yield and quality in China-A Meta-analysis

Min-hua YIN(), Yan-lin MA, Yan-xia KANG(), Qiong JIA, Guang-ping QI, Jing-hai WANG   

  1. College of Water Conservancy and Hydropower Engineering,Gansu Agricultural University,Lanzhou 730070,China
  • Received:2022-03-18 Revised:2022-04-18 Online:2022-09-20 Published:2022-08-12
  • Contact: Yan-xia KANG

Abstract:

Nitrogen plays an important role in the yield accumulation and quality improvement of alfalfa. However, supra-optimal nitrogen application to alfalfa crops not only causes a waste of nitrogen resource, but also aggravates environmental pollution. Additionally, the effect of nitrogen application on alfalfa production varies with different regional conditions and management practices. In this study, we searched the peer-reviewed papers reporting the effects of nitrogen application on alfalfa yield and quality, and quantitatively investigated the effect using meta-analysis. It was found that compared with no nitrogen application, nitrogen application significantly improved the yield and quality of alfalfa, and the mean increase in yield and crude protein content was, respectively, 12.6% (with a confidence interval of 9.0% to 16.2%) and 7.3% (with a confidence interval of 4.1% to 10.6%), and the mean decrease in acid and neutral detergent fiber contents was, respectively, 5.6% (with a confidence interval of 3.5% to 7.8%) and 3.0% (with a confidence interval of 1.0% to 4.9%). The effect of nitrogen application of increasing alfalfa yield and crude protein content and decreasing acid and neutral detergent fiber content was more pronounced in Gansu, in regions with an annual average temperature of <8 ℃ and an annual average precipitation of 200-400 mm, when using ammonium nitrate in split dressings with part as base fertilizer and part as top dressing, with irrigation, and with sowing rates of 26 to 30 kg·ha-1. However, there were differences in yield and quality for suitable nitrogen application rates and planting year. This study can provide a reference for the improvement of alfalfa productivity and the efficient utilization of nitrogen nutrition.

Key words: nitrogen application, yield, quality, alfalfa, Meta-analysis