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Nitrogen Fertilizer Giveaway, Part II

Posted Jun. 4, 2007

Six years ago, I wrote the first part of this article, entitled "Nitrogen Fertilizer Giveaway" (Ag News and Views, July 2001). Between 2003 and 2006, a project was conducted on the Noble Research Institute Headquarters Farm to demonstrate the possibility and practicality of pasturing stockers on bermudagrass while using legumes instead of nitrogen fertilizer.

Lime was applied prior to the study to adjust soil pH. Soil tests showed potassium to be adequate. Phosphorus fertilizer in the form of 18-46-0 was added to each pasture during each fall according to soil test recommendations. The grass base was bermudagrass with cool-season annual grasses. Various legumes, including alfalfa, arrowleaf, crimson, red and white clovers, and hairy vetch, were established using a no-till drill in 2002 and 2003 to evaluate their persistence. Stockers were rotated on four paddocks, which were later split into eight, and moved so that pastures received about 14 days of rest between grazing.

Over the four years of this study, average grazing days per acre per year were 153. The average grazing season length was 140 days per year, usually from March through July. There were more grazing days than days in the season due to stocking slightly more than one steer per acre. The average weight of the grazing steers was 615 pounds. Average beef production was 292 pounds of gain per acre per year, or 1.91 pounds of gain per head per day. Production costs were 17.7 cents per pound of gain. These costs included supplement, phosphorus, lime, seed, and application and planting expenses.

So what did we learn from this? First, legumes and rotational grazing are a good match. The necessary management skills are similar for both. Second, bloat was not a problem, and we really did nothing to control it, even on lush pastures. The fear of bloat is probably far more prevalent than the actual incidence of bloat. Third, I felt twice as dependent on the weather using legumes instead of commercial fertilizer, because first the legume needs good weather to grow, then the grass needs good weather to grow. Fourth, broadleaf weeds were not much of a problem. Many weeds were grazed. Where needed, chemical weed control was applied during two of the summers using a weed wiper and glyphosate solution. Fifth, this system may also work well for a spring-calving (April) cow herd. Sixth, and this is somewhat subjective, we received acceptable gains for an acceptable cost. Seventh, the most productive and persistent legumes for us were Patriot and Durana white clover and hairy vetch. Arrowleaf and crimson clover also made some contribution.

The high cost of commercial nitrogen fertilizer has many of you looking for alternatives. If you have suitable soil and moisture, consider adding legumes to your pastures. It may sound like a gimmick, but it's the closest thing we have to a nitrogen fertilizer giveaway.

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