Study of carbon, nitrogen, and phosphorous stoichiometry of twenty alfalfa varieties in the Horqin Sandy Land

After measuring the carbon (C), nitrogen (N), and phosphorus (P) content of 20 alfalfa varieties in the Horqin Sandy Land of Northern China, we calculated their C to N ratio, N to P ratio, and C to P ratio. The contents of C, N, and P significantly differed among the 20 varieties of alfalfa. The C, N, and P stoichiometry differed significantly among alfalfa varieties. Altogether, the N/P ratio of all 20 alfalfa varieties was lower than 14, indicating that the growth and development of alfalfa was mainly restricted by N availability. The alfalfa varieties tested were divided into three categories by cluster analysis, the first seven varieties being Reindeer, WL-343HQ, Zhaodong, Chicao No. 1, Longdong, WL-354HQ, and Gongnong No. 1. These varieties displayed strong structures, strong resistance to stress, and high nutritional quality. Therefore, they are suitable for cultivation in the Horqin Sandy Land. At the same time, a certain amount of N fertilizer should be applied. In particular, varieties showing the highest content of C and N in the aboveground part and the highest C content in the underground root system are characterized by strong resistance to stress and high levels of crude proteins, and thus are suitable for widespread planting in the Horqin Sandy Land.