Effect of Rhizobium dosage on growth of alfalfa in Kubuqi Sandland

The effect of Rhizobium dosage on the growth and nodule characteristics of alfalfa (Medicago sativa) was investigated in Kubuqi Sandland, Inner Mongolia. The seeds of alfalfa cultivar ‘4010’ were mixed with Rhizobium Dormal at ratios of 0, 10, and 20 g·kg-1 and then sown. Each treatment had three replicates. Indices of growth, nodules, yield, and nutrient contents were measured periodically. The results showed that Rhizobium had a significant influence on plant height, nodule formation, yield, and nutrition content at the first harvest (P<0.05). Rhizobium inoculation resulted in a 14-fold increase in nodule number compared with the 0 g·kg-1 treatment. The 20 g·kg-1 treatment resulted in the highest values for plant height and hay yield, resulting in an increase in plant height of 6.8 cm and an increase in hay yield of 1.79 t·hm-2. The 10 g·kg-1 treatment significantly decreased the stem/leaf ratio and resulted in a higher CP content and lower Acid Detergent Fiber (ADF) and Neutral washing fiber (NDF) contents at the first harvest. The maximum yield and best nutrition quality were not obtained simultaneously. In practical production, factors including cost also need to be taken into account when determining the optimal Rhizobium dosage.