Fertilization increased alfalfa yield and nutritive value in northern China: A Meta-analysis

Fertilization plays an essentially positive role in the yield and quality of alfalfa (Medicago sativa). However, the effects of fertilization on yield and quality of alfalfa vary with climate condition and fertilizer type. Thus, based on the peer-reviewed publications focusing on the effects of fertilization on the yield and quality of alfalfa across China, this meta-analysis was conducted to determine effects of fertilizer type on the yield and nutritive properties of alfalfa. Results indicated that compared with no fertilization treatment, all fertilizer types significantly improved the crude protein yield (CPY). The application of nitrogen and phosphorus fertilizer significantly increased crude protein and crude fat content (P < 0.05), and decreased acid and neutral detergent fiber content. When potassium fertilizer was applied alone, alfalfa CPY significantly increased in arid areas with an annual mean precipitation (MAP) of 200 mm. Nitrogen fertilizer was optimal for enhancing alfalfa yield in semi-arid areas with a MAP of 200～400 mm. Organic fertilizer reasonably increased yield and quality of alfalfa under different rainfall conditions. In summary, optimizing fertilization management in light of fertilizer type and climate condition is promising to improve the productivity and quality of alfalfa in northern China.