Alfalfa Rotations Save Dollars with Nitrogen Benefits

With high fertilizer prices affecting agriculture, farmers are looking for ways to reduce their nitrogen (N) inputs without sacrificing yield. Researchers have found that crop rotation with alfalfa can provide significant benefits in terms of N management.

Alfalfa is a legume that has been used for generations due to its ability to fix atmospheric N2 into ammonia through a symbiotic relationship with rhizobium bacteria. This process provides between 70% and 80% of the N requirement for alfalfa, with the remainder coming from soil sources or atmospheric deposition.

Studies have shown that wheat yields following alfalfa are often higher than those following grains, even when no fertilizer is applied. In one study, wheat grain yield benefited from rotation with alfalfa, and the crop also responded to N fertilizers under both systems, but the yield of wheat rotated with alfalfa was always higher.

The fertilizer equivalent value of the nitrogen provided by alfalfa is significant, ranging from 50 to 170 pounds of N per acre. At current urea prices, farmers can save between $20 and $120 per acre by rotating N-requiring crops with alfalfa.