Cotton Links


Early Decisions Crucial For Crop

By Amanda Huber
Southeast Editor

Researchers from agronomists to economists and from entomologists to weed scientists agree that the first 40 days after cotton is planted is the most critical time for the crop. This period is when yield potential and maximum quality are determined.

In fact, the components that make up the first 40 days are so critical that an exhaustive group of multi-disciplined, multi-state researchers and Extension personnel created a list of Best Management Practices for The First Forty Days, which has been presented in various venues, including the annual Beltwide Cotton Conferences.

How should the plant and crop look at 40 days?

According to the The First Forty Days white paper compendium, “An optimum cotton crop at 40 days after planting would have at least 30,000 uniform, stress-free plants per acre, with a plant height-to-node ratio of at least one.

This would be the primary goal for optimizing yield, fiber quality and earliness. Supporting criteria could also incorporate plant height, canopy coverage and plant health assessment, as well as a viable terminal and root system. At this stage, the healthy plant would have two to three squares.”

Free Of Major Problems

Furthermore, the authors say that the optimum cotton crop at 40 days would be free of stress from insects, mites, nematodes, seedling diseases, weeds and other manageable factors, such as fertility levels and water availability. The plant would exhibit healthy leaves, with roots extending into the row middles, and the crop growing rapidly and uniformly.

But these researchers also know that a healthy, stress-free crop doesn’t begin with the planting of the seed. Searching for where it does start is like asking the age-old question, “Which came first: the chicken or the egg?”

Decisions Start Year Before

Wayne Ebelhar, a veteran research agronomist with Mississippi State University, says the first decisions are made at the end of harvest.

“The question is, ‘what am I going to plant next?’ Am I going in continuous cotton, because what I do then is different than what I do for another crop, particularly for residue management,” he says.

Ebelhar, who is located at the Delta Research and Extension Center in Stoneville, Miss., says that many producers in his area will conduct most of the tillage in the fall of the year so that crops such as corn and soybeans can be planted early in the spring.

For cotton, which is planted later, more land preparation can be conducted in the spring.

“With cotton, if you plant too early, that seedling stresses easily,” he says. “The time of optimum planting dates is from mid-April to mid-May.”

Waiting until that time allows the seed beds to warm up adequately.

Ebelhar says that, on most crops, phosphorus and potassium applications happen in the fall before any tillage is done so that the nutrients are incorporated during the tillage process. These inputs do not move in the soil, unlike nitrogen.

“Across the South, other than wheat, you don’t have fall applications of nitrogen,” he says. “The biological transformations that occur eliminate the availability of it. Being able to take advantage of residual N is not a factor to consider.”

Apply When Necessary

Charles Mitchell, Extension agronomist and professor at Auburn University, says in his part of the country producers have gone more to conservation tillage.

“At this time of the year, they are deciding on whether to top dress the cover crop and when to kill it,” he says.

In Alabama, he points out that producers are advised to have as much residue as possible on the ground before killing it to obtain the maximum benefit from their nitrogen.

“Unfortunately, some producers don’t want to deal with all the residue,” he says.

Mitchell is a big proponent of taking advantage of what’s already in the soil.

“If your soils are testing high by land grant university standards, you don’t need to add phosphorus to cotton,” he says. “Research has shown that it does not have a positive yield response to adding any more.

“A cotton crop just doesn’t use that much. If you are low to begin with, then, yes, you will need it.”

Good Results With Urea

In 2008, Mitchell says his area had really good luck side-dressing his crop with urea.

“The idea that you need to avoid it is not necessarily so,” he says. “Our best yields were with dry urea. It did better than the ammonium nitrate.”

Mitchell says he always recommends that producers apply about one-third urea at planting and then the rest at side-dress.

“Most of our cotton is non-irrigated,” he adds. “If you get a lot of rain in May and June, you can lose all of the N applied at planting. Splitting the application gives you some insurance.”

Another research project that Mitchell is involved in is a long-term rotation experiment.

“In 1997, we switched from conventional tillage to high-residue conservation tillage,” he says. “We subsoil under the row, but it is not tilled.

“It greatly improved the water-use efficiency. The moisture soaks in, and the soil is able to hold it.”

Value Of A Timely Burndown

Saving soil moisture for the crop is one reason for timely burndown, says Phil Bauer, research agronomist with USDA-ARS in Florence, S.C.

“One of the reasons to kill cover crops early is not to deplete the soil moisture,” he says. “If you have cover crops and/or weeds and it’s a dry April, although the recommendation is two to three weeks before planting, if it’s dry, you may want to kill it sooner.”

Also, Bauer says, you want to make sure weeds are controlled and that there is not any green when you go into planting.

“This is particularly important where there may be resistant pigweed populations,” he says.

However burndown is accomplished, researchers recommend that producers plant into a weed-free seedbed and treat weeds in a timely manner to eliminate weed competition for a full six to nine weeks after planting.

Contact Amanda Huber at (352) 486-7006 or ahuber@onegrower.com.

Best Management Practices For The First 40 Days

• Based on field history, choose an at-planting systemic insecticide with residual properties.

• Choose varieties with genetic potential for higher yield and fiber quality.

• Plant 2.5 to 4 uniformly spaced seeds per foot, drilled or hill-drop pattern, with good seed-to-soil contact, warm soil temperatures and adequate soil moisture.

• Don’t rely on a single weed-control system; use multiple modes of action and residual herbicides

• Treat weeds in a timely manner and eliminate weed competition for six to nine weeks after planting.

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