How Much Nitrogen Will Clover Put in the Soil?

Amount of Returned Nitrogen

• In a pasture containing 20 to 30 percent clover, the legume fixes or returns 80 to 200 lbs. of nitrogen in every acre of soil, according to the Mississippi State University Extension. The variation in this amount results from growth conditions and the clover species. This is usually enough nitrogen for the healthy growth of the entire pasture. This translates into a saving of $40 to $50 per acre of required nitrogen in the field.

Benefits of Clover Fixed Nitrogen

• Nitrogen returned to the soil by clover is in the form of decaying plant tissue, which doesn't pollute the surrounding area, as in the case of manmade nitrogen sources. Artificial sources of nitrogen are mobile chemicals that are likely to leach into underground water sources with extensive rainfall and irrigation. Nitrogen like urea also evaporates into the air.

Process of Nitrogen Fixation

• The common soil bacterium Rhizobium starts to grow within clover roots after planting. After a week or two, small finger-like nodules appear on the roots. The white nodules gradually turn pink as the nitrogen fixing process begins. Air contains about 80 percent nitrogen that is unusable in its pure form by the majority of living organisms. Through the process of nitrogen fixation by bacteria, this inert nitrogen is changed into biologically useful nitrogen.

Clover Planting Recommendations

• Experts at the Mississippi State University Extension recommend mixing 20 to 30 percent clover with 70 to 80 percent pasture grasses. This ratio helps with optimal grazing and supplies enough nitrogen to support healthy growth of the entire pasture. If you're planting clover in established pasture, mow the existing plants short to reduce competition with new clover plants.