Beat the High Cost of Nitrogen Fertilizer
by Dan Undersander 

Fuel prices have risen greatly this winter. Since nitrogen fertilizer is made using natural gas, its price has also risen significantly and is likely to continue to rise. Some farmers and consultants are even considering that the marginal returns from high nitrogen fertilization rates on corn may not be present unless corn prices rise. 

But there is one other option that alfalfa growers should be considered this spring – legume credits from plowing down alfalfa now have increased value. As the table indicates, plowing down alfalfa can provide most or all of the nitrogen needed for the next corn crop. 

If thicker alfalfa stands are plowed down (e.g. 5 plants/ft2 rather than 1.5 to 4 plants/ft2), more nitrogen is returned to the soil for the next crop. Considering that the current cost of nitrogen is $.30 to $.41 per pound of nitrogen, the value of legume credits for 120 lbs nitrogen per acre is 
 
$40 to $49.2 per acre and for 150 lbs of nitrogen incorporated is $50.00 to $61.50 per acre. Any stand with less than 6 plants per square foot will too thin for high alfalfa yield. 

This is clearly the year to plow down those marginal stands of alfalfa, take the nitrogen credits and replant other alfalfa fields to have the highest possible yields of alfalfa. Keep in mind that corn will also yield 10 to 15% more grain or silage following plowed down alfalfa than following corn. 
 
Legume credits from varying alfalfa stands heights and densities