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Corn+Soybean Digest

Litter Lowdown

Cotton yields 20% higher, with reduced fertilizer costs. That's not chicken feed — it's chicken manure.

Growers benefit from using poultry litter rather than conventional fertilizer — without hurting the environment, according to Louisiana State University (LSU) Agricultural Center research.

Two tons of poultry litter increased lint yields by 100-150 lbs./acre during five years of testing at north Louisiana sites, says Jim Rabb, an LSU AgCenter agronomist. “That's a jump from 750 lbs./acre to 850-900 lbs./acre,” he says.

The largest animal industry in Louisiana, poultry is also huge in Arkansas, East Texas and other Southern regions. Poultry litter is a combination of manure and bedding material. About 180,000 tons of litter are produced annually in Louisiana alone.

Litter costs about $15/ton — depending on how far litter must be transported. It helps reduce fertilizer costs and increase yields, Rabb believes. In his Louisiana research, cotton is grown in a minimum-till system. After fall harvest, cotton stalks are destroyed. Fields are then left untouched until about three weeks before planting the following spring.

“That's when a broadcast spreader is used to apply 2 tons of litter per acre on some fields, and 4 tons on others,” says Rabb. “It's applied instead of a typical 60- to 70-lb. application of N.”

Poultry litter is about 3% nitrogen (N), 2% phosphorus (P) and 2% potassium (K). So the average nutrient content is the equivalent of about 50 lbs. each of N and P and 40 lbs. of K. However, the nutrient value can vary from 34 to 90 lbs. of N, 32 to 66 lbs. of P and 16 to 48 lbs. of K per ton of litter.

Rabb's findings consistently show that 2 tons of poultry litter generate the same yield as 4 tons. And both applications consistently outyield conventionally fertilized cotton.

In northwestern Texas, dried manure from cattle feedyards is applied to fields to be planted in cotton, corn, wheat or grain sorghum. A ton of this manure, at 35% moisture, contains about 25 lbs. N, 15 lbs. P and about 20 lbs. K, as well as other minerals. Nutrient amounts can be even higher with composted feedyard manure. Yields are comparable to those from crops receiving anhydrous ammonia applications.

Rabb and his associates constantly monitored runoff from fields treated with poultry manure. “There have been concerns about excessive phosphorus, zinc and copper runoff from the litter,” he says. “But our studies have shown that levels for these heavy metals have not exceeded limits allowed by the Environmental Protection Agency.”

In addition to stronger cotton yields, litter applications also help build up the soil.

“Traditionally, this region's silty loam fields, which have seen heavy cotton production, have been low in organic matter,” says Rabb. “But applications of poultry litter have increased the organic matter up to 1%. The pH levels of the soils have also been improved.”

Rabb has not researched the benefits of litter on corn or soybeans in rotation with cotton. But he believes yields for those crops might also be improved. “We feel it's important to rotate crops when possible,” he says, “and the increase in organic matter should benefit crops rotated with cotton.”

Control Early Season Insects

Spraying early season cotton insects is one of the best options producers have to manage their crops for early maturity and harvest, according to Jim Leser, Texas A&M extension cotton entomologist.

“Spraying late is not profitable,” Leser says. “Regardless of the pests they face, growers who base control decisions on a realistic target yield, and then spray to make money instead of simply spraying to eliminate pests, will come out ahead.”

Thrips are one of the most important early season pests to watch for in irrigated cotton, says Leser.

“Western flower thrips are the chief culprit on the Texas High Plains. Their feeding damages both leaves and squares on the plant. Studies have shown that we can boost yields by as much as 21% if we control early season thrips,” he says. “Foliar insecticides are a good, cost-effective choice for thrips control — especially in narrow-row cotton. Foliar applications should be based on the number of mature and immature thrips in the field. Timing is crucial, too, since thrips generally disappear once the plants set squares.”

Lygus bugs can threaten late-planted, stress-susceptible cotton if the bugs live in these plants and in roadside weeds during spring. In summer, sunflowers and sweet clover also harbor this pest Leser adds.

“Lygus bugs feed on cotton squares and immature bolls, so we must watch for them and be prepared to apply a control treatment through squaring and boll initiation. Their damage potential declines once the plants accumulate 350 heat units after the first flowers appear,” he says. “Early squares make our lint crop, so we have to protect against insect damage right up through squaring and flowering. Managing for early plant maturity and protecting plants from early season insects also makes the crop less vulnerable to later-season boll-feeding insects.”

PhytoGen Offers RR Pima

PhytoGen Seed Co. announced that it will introduce the first Roundup Ready Pima cotton variety along with the first Roundup Ready varieties in its product mix for the 2004 growing season. And, if EPA provides final registration, the Indianapolis-based seed company plans to market two new varieties containing the WideStrike Insect Protection trait, too.

Four new PhytoGen varieties will include the Roundup Ready trait:

  • PHY 410R, and early-to-mid maturity Roundup Ready variety adapted for the Midsouth, Southeast and Southwest;

  • PHY 510 R, a full-season Roundup Ready variety adapted for the Southeast and southern areas of the Midsouth;

  • PHY 710 R, a Roundup Ready Acala;

  • PHY 810R, the first Roundup Ready Pima variety available.

“These varieties have demonstrated high yield potential and good-to-excellent fiber quality in 2003 company and university tests,” says Joe Sobek, global cotton business leader for Dow AgroSciences. PhytoGen is a joint venture between Mycogen Corp., an affiliate of Dow AgroSciences LLC, and the J.G. Boswell Co.

All the new varieties will be in limited supply for 2004 and packaged in 50-lb. bags, according to the company.

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