Cotton Behind Wheat Works In Louisiana
February 10, 2009 The jury returned the verdict several years ago: Yes, cotton can be an economic success double-cropped with wheat in Louisiana.
Past the point of knowing that it can be done, Louisiana is looking at how it can be done better.
For instance, what stubble-management program works best? Are there varieties that perform better behind wheat than others? And then there’s testing going on that might have some positive results you haven’t even considered.
Stubble Management
“We want to know what stubble-management practice would be the most optimal to maximize yield,” says Rob Ferguson. Ferguson is a graduate student at Louisiana State University, helping monitor field trials at the Dean Lee Research and Extension State in Alexandria under the direction of Louisiana Extension cotton specialist Dr. Sandy Stewart. “We’re trying to determine which way to best handle the stubble to maximize yield.”
In 2007, Ferguson’s first test plot was for cotton only, planted into stale seedbeds during the first few days of May. On May 23rd, that test was replicated alongside plots with cotton planted into 6- and 12-inch tall wheat stubble, and stubble that had been burned.
“What we saw in the stubble management trials was that we didn’t have any significant yield difference in the treatments,” Ferguson says. “We found that the plant populations were reduced in stubble treatments, but it was still adequate — there was enough of a stand there to consider it a good stand.”
A Variety of Varieties
As far as varieties, Ferguson says, “You intuitively think a short-season variety would perform better planted that late after wheat, and we wanted to know which one of those varieties will maximize yields.”
But, contrary to intuition, Ferguson says it was a late-season variety that actually led the yield trials.
“At first we thought the shorter-season varieties would be the most ideal,” he says. “We want to know what the deciding factor is in determining a variety. It may not be that the short-season variety is better suited. We have to understand growth habits.”
The late-maturing variety that led the test in yield was Delta and Pine Land’s DP 555 B/R. “What that leads us to believe is that maturity might not be the only thing to consider,” says Stewart. “Grow a variety that’s well adapted to your area anyway.”
Another Revelation?
There is state-wide water-quality testing going on in Louisiana conducted by Donna Morgan, area agent, Master Farmer Program, at the Dean Lee station, analyzing runoff from fields and pastures after rains and irrigations.
“We want to know what (the water quality) is coming off fields and pastures,” she says. “What we are finding is that most samples are within LDEQ (Louisiana Department of Environmental Quality) acceptable standards.
And then she added what could ultimately make cotton following wheat an even more efficient system: “We’ll have a spike (in water quality) every now and then – after they might have put out fertilizer, or after we get a 3- or 4-inch rain on a field.”
See relationships with cotton behind wheat? With the collection equipment she has, at some point it could be used to measure the fertilizer that was applied to a field that stayed there, and what didn’t. The less fertilizer residue there is in runoff water, the more efficient and lower cost a fertilizer application might be. An added benefit would be improved irrigation efficiency. Same deal as with fertilizer: Less runoff, lower cost, better efficiency.
These practices are excellent examples of the agricultural industry being proactive in environmental stewardship and implementing best management practices, which is exactly the purpose of the Master Farmer Program.
Captions:
Cotton seedling emerging through wheat stubble.
A runoff water collector in a cotton field.
Timing Is Everything
What’s your chance of success planting cotton behind wheat? It’s all in the timing.
With wheat prices rising to new highs, many farmers have taken advantage of what they see as a tremendous opportunity and have planted record wheat acreage in the Mid-South.
While double-cropping wheat and cotton remains a relatively uncommon practice in the Mid-South, several studies show that it can work if wheat harvest is timely enough so that cotton can be planted in May. Research further shows that the odds of success improve under irrigation, assuming cotton is planted in a timely manner.
But with almost total dependence on the weather, double-cropping cotton behind wheat remains risky, and can result in reduced lint yields.
Louisiana has a longer growing season than most of the Mid-South, and Dr. Sandy Stewart, Louisiana Extension cotton specialist at the Dean Lee Research Station in Alexandria, LA, says the successes of boll weevil eradication and the availability of Bollgard II/Roundup Ready Flex varieties have allowed producers to extend it even further, making cotton behind wheat a viable option.
A shortage of soybean seed may also lead growers to consider cotton rather than soybeans behind wheat.
“I think it is a very workable system,” says Stewart. “We have some growers that have several years of experience double cropping cotton behind wheat.”
A grower’s success is dependent on several factors. Ideally, Stewart says the cotton should be planted on rows formed in the fall. “I wouldn’t recommend planting cotton flat,” he says.
Other factors that improve a grower’s chance of success are the planting of an early maturing wheat variety and an early wheat harvest. “We’ve been able to harvest wheat one day in late May and plant cotton that day or the next day and it seems to work. The cut-off day to plant cotton in this area is June 10. After that it is too late to produce a viable cotton crop,” says Stewart.
Wheat stubble management is also crucial, according to Stewart. In Louisiana studies, cotton yields were not adversely affected when cotton was planted into 12-inch wheat stubble, 6-inch wheat stubble, or a burned-off seedbed. However, differences were documented when stubble management affected seed to soil contact.
Take Out The Trash
“If you plant directly into wheat stubble, always use trash wipers on the front of the planter,” Stewart says. “The key to successfully using the trash wipers is to correctly judge depth based on soil moisture. The trash wipers should be run only as deep as needed to remove some straw and still have a relatively smooth seedbed. Moisture will dictate how deep this needs to be,” advises Stewart. “If you are operating under dry conditions, run the wipers very lightly to clear a path for the double disk opener on the planter. If there is adequate soil moisture present, you can go a little deeper. Do everything you can to conserve soil moisture to insure the seed will germinate as quickly as possible. Ideally, double-cropped cotton is planted on irrigated acreage.”
Once an adequate cotton stand is established, Stewart recommends managing the cotton as you would any other late-planted cotton crop.
Growers trying the system for the first time might be surprised to see shorter cotton plants that can be slow to canopy. “We’re not sure the exact reason, but the data is clear with some resulting implications for plant growth regulator programs and weed control,” Stewart says.
He recommends a less aggressive PGR program due to the relatively low risk of rank plant growth. In addition, a late to non-existent plant canopy can provide more opportunity for weeds to compete with a cotton crop. “An early pre-emergence herbicide application is the key to this system, recognizing that late season grass pressure will come into play if you don’t reach full canopy. You will also want to grow a Roundup Ready Flex variety because it gives you the ability to control weeds in-season.”
Editor’s note: Information for this story was provided by Doreen Muzzi, an agricultural journalist from Shaw, MS.
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