Cotton planting management highlighted in two AgriLife Extension studies

By Kay Ledbetter

Texas A&M AgriLife Extension

New and returning cotton producers may want to carefully consider row spacing and seeding rates when they get ready to plant seed in the next few months, according to two Texas A&M AgriLife Extension Service agronomists.

Jourdan Bell in Amarillo and Emi Kimura in Vernon recently released the results of two cotton trials dealing with row spacing and seeding rates.

Bell said she conducted a row-spacing trial with AgriLife Extension agents Kristy Slough, Hutchinson County, and Andrew Sprague, Hansford County, to look at new early maturing cotton varieties, which are yielding greater than the more determinant varieties planted in the High Plains.

“We have producers inquiring about continuing the practice of planting on narrow, 20-inch row spacing as a strategy to enhance maturity and yield with newer varieties,” she said.

On average, northern High Plains producers plant cotton using a seeding rate of 2.5 to 3.5 seeds per row foot on 30-inch rows, Bell explained. To maintain the recommended seeding rate per row foot, planting populations increase as row spacing decreases. Increased seeding rates can result in increased inter-row competition that could affect boll and fiber development.

The Hutchinson County cotton row-spacing trial evaluated the lint production and fiber quality of FiberMax 1320 and Stoneville 4747 on three row spacings—20, 30 and 40 inches. It demonstrated significant variety and row spacing interactions.

Stoneville 4747 yielded greater on all row spacings, with the greatest lint production being on 30-inch rows. The 40-inch row spacing yielded the lowest for both varieties.

Bell said while yields were lowest on the 40-inch rows, there were no significant differences between the final four-week plant stands on the 30- and 40-inch rows, suggesting differences were not the result of a greater number of fruit-bearing plants on the 30-inch spacing.

She said the trial will be repeated in 2018 and 2019 to obtain a three-year dataset necessary for evaluation of a management practice under varying environmental conditions.

Results of the Hutchinson County row-spacing trial can be found on Page 41 of the 2017 Replicated Agronomic Cotton Evaluation, or RACE, trial results at http://bit.ly/2C7fDRD.

Kimura planted her seeding rate trial in 2016 and 2017, with the most recent crop harvested Nov. 17. She said traditionally, cotton producers in the Rolling Plains plant 2 to 2.5 seeds per foot for dryland conditions and 3 to 4 seeds per foot in irrigated cotton.

The study was conducted to determine the best seeding rate for lint yield and values, comparing rates of 22,216, 44,431, 57,499 and 73,181 seeds per acre in 40-inch spacing, Kimura said.

“We found the lower seeding rates seemed to produce the same amount of lint yield under favorable environmental conditions,” she said.

Over the two years, there were no differences among all seeding rates in the irrigated trial, but net dollars per acre were the highest at 22,216 seeds per acre in the dryland trial, Kimura said.

However, she cautioned, while the low seeding rates may perform as well as higher seeding rates, they may be more susceptible to harsh environments such as hail, sandstorms and dry conditions.

Results of Kimura’s trial can be found at http://bit.ly/2EEr5BR.