Soils: February 2001

October, 2000 rains provided the soil moisture needed to obtain better-than-expected small-grain pasture stands. However, the rain, sleet, and snow have yet to end. Excess rainfall and cool temperatures limited fall forage production and induced phosphorus deficiency symptoms in small grains throughout the region. Symptoms of the latter include purpling of the lower leaves and limited root development.

A question one might have is how will the excess soil moisture and poor fall forage production affect spring forage production potential? Forage yields should be high this spring. The excess rainfall has provided enough soil moisture to support spring forage production through graze-out. Stands that were fertilized in the fall should not receive too much nitrogen carry-over for spring forage production. Small-grain forage production studies performed by Wadell Altom and Jerry Rogers at the Noble Foundation indicate that less than one-third of the nitrogen fertilizer applied in the fall is available for spring forage production. A spring top-dress application of nitrogen is crucial in maximizing forage production. A nitrogen fertilizer application will not only increase forage production, but also increase forage quality as well.

The lack of fall forage did not allow much beef production through December. However, as much as 3 pounds of gain per day can be expected this spring if fertility management is proper. Weather predictions call for above-normal temperatures through the spring. Therefore, an early nitrogen topdress application will allow additional days of grazing, each one of which will provide the opportunity for more beef production.

The recommended rates for nitrogen fertilization this spring may vary. If you applied 100 pounds of nitrogen per acre in the fall, then you should top-dress with a minimum of 60 pounds of nitrogen per acre. If you applied anything less in the fall, top-dress with 80 to 100 pounds of nitrogen per acre. These recommendations apply if the additional forage produced from fertilization can be sold for more than the cost of fertilizer. All top-dress applications should be applied early in February.

Fertilizer prices increased considerably in January. It is not uncommon for 1 pound of nitrogen fertilizer to cost more than 30 cents per pound, depending on the source of dry-nitrogen fertilizer used. Note that each pound of nitrogen fertilizer applied can produce as much as 25 pounds of small-grain forage in the spring. One hundred pounds of nitrogen fertilizer (30 cents per pound) costs 30 dollars per acre and can cost an additional 3 dollars per acre if custom applied. However, this input can produce 2,500 more pounds of forage per acre (100 pounds of nitrogen x 25 pounds of forage per pound of nitrogen applied) than natural fertility can. Assuming it takes 10 pounds of forage to produce 1 pound of beef and each pound of gain is worth 35 cents (customary charge for gain on small-grain pasture), the 30- to 33-dollar investment per acre for nitrogen fertilizer can yield a gross return of approximately 87 dollars more per acre than natural production: (100 pounds of nitrogen x 25 pounds of forage per pound of nitrogen applied = 2,500 pounds, which divided by 10 pounds = 250 pounds of beef produced) x 35 cents per pound of gain = 87.50 dollars. After deducting the 33 dollars for the cost of fertilizer, there is 54.50 dollars left to help pay for other production costs.

From the simple example above, one can see the value of nitrogen fertilization in relation to profitability. However, it is important to evaluate your own stocker enterprise to determine what nitrogen fertilizer rate will best meet your forage production needs. If stocking is heavy, you will need a higher rate of nitrogen to meet the forage demand. If it's light, then you'll need less.