Scientists Work to Improve Dryland Yields

by C. Richard Maples
Extension Specialist - Agricultural Communicationsp> In a perfect world, every soybean field could be watered when it doesn't rain. But not a perfect world, and about 56 percent o Arkansas' soybean acreage is in dryland production.

That's why, for fiscal year 1995-96, the Arkansas Soybean Promotion Board's large,, block of funding went to the University of Arkansas for research to improve dryland profitability.

Much of the dryland research effort is being guided by Dr. Terry Keisling, an agronomist headquartered at the Northeast Research and Extension Center, Keiser.

"One thing we're investigating is drough avoidance," says Keisling. "At several sites, clay and silt loam soils, we planted indeterr nate Group III and I varieties, along with determinate Group V soybeans, in April.

"We wanted to see if the different maturity groups could utilize the more frequent rainfall in April, May, June and July and avoid the drought conditions that often occur in August and September."

Researchers are also investigating drought avoidance by using early planted soybeans with various seedbed preparations - deep tillage, fallow using chemicals to prevent weeds from using up moisture, and conventional tillage.

Another approach to drought avoidance being studied is to leave the soil fallow but delay planting until June or July. The idea is to conserve moisture that might otherwise be lost to weeds and evaporation during May and June. Fall rains will then finish producing the crop.

About $35,000 of the checkoff funds supporting Keisling's work is being used to investigate deep tillage.

He noted that USDA/ARS ag engineer Dr. Richard Wesley's work at Stoneville, Miss., has shown that deep tillage on some heavy clay soils has increased dryland yields 5-16 bushels per acre during the past five years.

Referring to Wesley's field studies, Keisling said, "If you deep till in the fall, it has to be done when the soil is dry. More soil moisture is being made available to roots, which could prevent beans from running out of water in July and August.

"Deep tillage also enhances root depth. In heavy clay soil on the Mike Oxner farm near Cody, indications were that plants were removing moisture from depths of more than 5 feet."

Keisling is looking at ways to lower dryland production costs as well increase yields. At the UOEA experiment stations at Keiser and Pine Tree, he's used one-pass operations to till, see and apply herbicides.

"If it's done early, when weeds are small, mechanical tillage can iit,gate the need for bumdown herbicide," he said. "The tillage operation costs abo $4.50 per acre. You seed your soybeans during the tillage ope ation and end up with production costs somewhere between $30 and $40 per acre prior to harvest.

"In most dryland systems, production costs are about $60 to $80 per acre."

Keisling added that, so far, he's seen no difference in onepass and conventionally plante no-till soybeans.

Keisling has been loaned an impressive array of equipment his low input work at the Pine Tree Experiment Station. "It includes a high quality field cul vator with very good depth control that can be pulled behind a Concord air seeder, followed by crumbler that firms up the soil on top to a depth of about 1 inch.

"The advantage of this onepass system versus a drill is th you can plant a strip up to 50 feet wide at 8 - 10 miles per hou Plus, it can be operated by one man."

Keisling stresses that this "low input" approach won't wo everywhere. "It won't work if yo have too much residue in term of weeds and root mass. If you' doublecropping and the soil is very hard and dry, and there's too much stubble, it won't work.

You must pay close attention to stubble and root mass, and the depth of tillage for the one-pass system to work consistently."

The field cultivator in the one-pass system has given Keisling an opportunity to study the effects of shallow tillage, leaving a considerable amount of residue on the surface, and planting at the same time.

"My research has shown th with full season soybeans, disk ing 3-4 inches and leaving muc of the residue on the surface is wor-th about 10-14 bushels per acre during a dry year.

"Tillage itself has, on occasion, improved yields by as much as 10 bushels. Leaving the residue on the surface can reduce evaporation, which can increase yields by 2-6 bushels per acre."

All of these projects being funded by grower checkoff funds have one goal - to increase dryland profits by increasing yields or reducing production costs, or both.

Contents | From the Chairman | Soybeans' versatility | Checkoff money wise investment | Improving dryland yields | SRVP helps young farmers | SRVP boosting profits | Improving drought tolerance | Reduced rate weed control | Roundup-ready soybeans | Disease control | Soyink | Computer irrigation scheduling | SOYVA | Early maturing varieties