High energy costs may be forcing farmers to take a harder look at fertility and tillage systems this spring as they prepare for another close-to-the-bone production season.
Reducing trips across the field, if the reduction doesn't result in lost yield, can take a significant chunk out of production expenses, says Randy Boman, Texas Extension cotton specialist, Lubbock.
And if soil tests indicate adequate fertility levels, farmers may tap nutrient credits to help make this crop.
“Minimize tillage where feasible,” Boman says. “But consider each specific situation.”
He cites research data from the AGCARES facility at Lamesa, which shows reduced tillage as the most profitable option for dryland cotton. A terminated small grains cover crop system proved best under irrigation.
Results from the five-year study under a LEPA irrigation system show:
Conventional tillage (shredding stalks; breaking, listing and furrow diking; rodweeding and diking; sandfighting, and cultivation and diking) averaged 909 pounds of lint per acre with net returns of $225 per acre.
Minimum tillage (shredding stalks, relisting old rows to incorporate preplant herbicides and furrow diking; rodweeding and diking; sandfighting, cultivation and diking, and drilling small grain after harvest) averaged 916 pounds of lint per acre and net returns of $235 per acre.
Terminated rye/wheat-cotton averaged 1,025 pounds of lint and $282 per acre returns. (A cover crop of wheat or rye is planted into cotton stalks after harvest each fall and chemically terminated two to four weeks before planting cotton directly into the crop residue in the spring. Fewer field operations but more herbicide inputs are required. The cover crop reduces wind erosion.)
The research included deficit irrigation at a 0.75 evapotranspiration (ET) rate.
“The terminated grain system does not appear to work as well under dryland conditions since the cover crop consumes precious moisture,” Boman says.
In dryland research, results show:
Minimum tillage produced 354 pounds of lint and $93 per acre in net returns.
Conventional tillage averaged 199 pounds of lint and $2 in returns.
Terminated wheat/rye-cotton averaged 195 pounds of lint and $14 per acre.
“Fertilize for a realistic yield goal,” Boman says. “Soil tests can pay.”
He says a cotton crop removes about 45 pounds of nitrogen and 25 pounds of phosphate per acre. However, with the inefficiencies associated with nitrogen in soil and plants, producers should plan on 50 to 60 pounds of nitrogen per bale of yield goal.
“If the previous crop was well fertilized and yield was poor, residual nitrate-nitrogen likely will be present in the soil profile,” Boman says. “Test it!”
Applying nitrogen fertilizer through a center pivot irrigation system also may lower cost. Boman cautions growers about applying nitrogen through spray systems if water quality is marginal.
“Salt burn on foliage may result.” A LEPA system, with drag hoses, may be a better option.
Boman says growers who hesitate to apply all their nitrogen early to avoid “front-loading expenses can sidedress after the crop is established. Nitrogen applications are more likely to stimulate growth and promote fruit retention. Adjust nitrogen to fit yield potential.”
He says dryland cotton will require 30 to 50 pounds of nitrogen per acre. “Use higher rates if the yield potential (stored soil moisture) is higher.”
Boman says farmers should complete sidedressing before cotton starts blooming. “Benefits from low rates of foliar fertilizers are questionable,” he says.
Other nutrient recommendations include:
Phosphorus. If soil tests are high enough, economic returns to phosphorus may not be realized. Again, soil test to make certain it's needed.
Potassium. Base application rate on soil tests. “A soil test value of 125 ppm extractable potassium is sufficient for cotton.”
Sulfur need is related to nitrogen. For every 10 to 20 pounds of nitrogen required, cotton needs about one pound of sulfur. “From five to 15 pounds of sulfate-sulfur per acre should meet the needs of bumper crops in our region,” Boman says.
Zinc. Again, assess with a soil test to assure at least 0.30 ppm. If tests show a deficiency, three to six pounds per acre of zinc sulfate (resulting in one to two pounds of elemental zinc) per year should be adequate.