Arkansas farmers who planted cover crops successfully last fall likely gained a bit of time planting the 2020 cotton crop. It was a challenging planting season.
Tropical storm Cristobal dumped from 1 to 4 inches of rain in Arkansas alone. Cotton farmers in the state have seen excessive amounts of rain from a wet fall and an early start to the tropical storm season.
Large amounts of rain over an extended period of time can be devastating. Too much rain during planting or harvest can saturate fields, which prevents easy access to crops.
Bill Robertson, University of Arkansas Extension cotton specialist, says last fall proved a difficult time for cotton farmers to harvest their cash crops and begin planting the cover crops.
"Last year we had a late harvest, and then it turned off cold and wet. The cover crops that were seeded didn't have the right environment to grow much," Robertson says.
Farmers who did manage to establish cover crops in less than favorable conditions saw the benefit at planting time.
"The fields with the cover crops were some of the first fields we were able to get in because they could hold up a planter," Robertson says. "Those cover crops got us in the field quicker."
Cover crops offer many other benefits for cotton farmers.
"When we think of cover crops, we think of improving our soil health," Robertson says.
He cites four main factors to consider for increasing soil health. The first is to armor the soil.
"Keeping the soil covered reduces evaporation of moisture from the soil and limits erosion," Robertson says.
Another benefit to sustaining a cover crop in the off season is keeping live roots in the soil, even when the cash crop is not in season.
"Having (live roots) as many months out of the year as you can increases the interaction with microbes in the soil with the roots and organic matter," Robertson says.
If farmers want to keep their soil robust, another objective is to diversify their cover crops as well as their cash crops.
"That will help the variety of microbes in the soil," Robertson says. "These first three things build the soil structure and feed the microbes."
Roberts' fourth suggestion concerns protecting the soil structure once it's built.
"You should greatly reduce your tillage. We built the soil structure, so we don't want to destroy it with one big, deep tillage. If that happens, we destroyed everything we gained with the first three steps," Robertson says.
It's easy to see the benefits of cover crops for soil health, but Robertson says other benefits can improve irrigation efficiency.
"Water infiltration rates are about half an inch per hour on our silt-loam soils. A big rain of 2 or 3 inches causes most of the rainfall to run off. When farmers incorporate cover crops into their production system, it's not unusual to see infiltration rates go up to 6 or 8 inches per hour. That is why we often see our greatest benefits from cover crops in dry conditions," Robertson says.
Cover crops behind cotton can be planted as early as mid-September and some producers terminate about two to four weeks before the cotton planter comes through the field in mid-April to early May. Their objective for early termination is to avoid the "green bridge."
"We don't want to give pests the green bridge from the cover crop to the cash crop. Farmers need to ensure that no green tissue is left behind by cover crops. If the cover crop isn't fully terminated, pests feed on the leftovers until a new source of food comes along, and that would be our cash crop," Robertson says.
One of the biggest issues to determine when to terminate a cover crop is knowing when to get the planter in the field to plant the cash crop.
"Some weeks we can put the planter in the field, but some weeks we can't. In a wet spring like this year, we had few consecutive days to plant, so it's hard to gauge that time frame," Robertson says.
Knowing the cover crops' potential issues could be a key factor in preventing the green bridge and having success planting into green cover crops.
"(Farmers) should scout cover crops to know which types of plants or weeds they have and what insects are on those plants. That will go a long way in helping them avoid problems," Robertson says.
While the implementation of cover crops can be tricky, the benefits are well-proven to give cotton farmers a leg up, even in wet seasons.