When farmers enter their fields in the Arkansas Soybean Association “Grow for the Green” Yield Contest, they submit detailed information on what they did to produce yields of 100 bushels or more.
That information – minus their identities – enters the public domain, which means it can be used by researchers such as the University of Tennessee’s Angela McClure to help their producers enhance yields and bottom lines.
“I went into the data from 2013 to 2015 just to see how many guys made 100 bushels per acre and what they were doing,” said Dr. McClure, Extension corn and soybean specialist with the University of Tennessee, referring to the Arkansas Soybean Association’s Grow for the Green Challenge.
“So they had 147 producers who qualified, and seven made 100 bushels or better. (In her presentation, Dr. McClure said nine producers grew more than 100 bushels, but one of those grew more than 100 bushels per acre all three years, leaving seven.)
Dr. McClure listed the common practices of all seven for farmers attending her “Pursuing High Soybean Yields” at the University of Tennessee’s Milan No-Till Field Day:
- Seeding rates, she said, were “moderate,” ranging from 140,000 to 175,000 seed per acre with most in the 140,000- to 150,000-seed per acre range.
- Varieties. The 100-bushel-plus growers used a total of eight different varieties over the three years. “So there is more than one high-yielding variety out there, which is good news for us,” she said.
Planting on raised beds
- All the soybeans were planted on beds, either on 30- or 38-inch rows. “They have great soil drainage,” she noted. “I think that’s one of the reasons they’re able to push those yields as high as they are in Arkansas.”
- Seed treatments. Each of the 100-bushel-plus growers used seed with an insecticide or fungicide or both on it. Some also applied micro-nutrients on the seed.
- Irrigation. All irrigated their soybean yield entries, all with furrow systems.
- Planting date. “Eight out of nine (or six of seven, in actuality) planted in April,” Dr. McClure noted. “We’ve been talking about that, and, if soil conditions are good, think about planting earlier, in April, if possible.” (Recent studies have shown a four-bushel-per-acre increase for April over May plantings in west Tennessee.)
- Insecticides – Most made one or two applications for damaging insects.
- Poultry litter. “Three-fourths of the farmers used poultry litter,” Dr. McClure said. “Poultry litter is a great slow release P and K material. You have to watch the quality. The other thing poultry litter supplies – if you’re interested in 100-bushel yields – is nitrogen.”
- A little more than half of the growers applied potash or a combination of potash and nitrogen above that provided by the poultry litter.
- About half added a product of choice to boost yields.
“We typically don’t put nitrogen on soybeans because they make their own, but if you’re trying to make yields above 60 to 65 bushels, that plant gets to the point where it can’t make enough of its own, and it has to take it out of the soil. We don’t have a lot of residual nitrogen in our soils so the idea of adding it may be important.
Combination of a number of things
“So basically a lot of stuff went into 100-bushel soybeans,” she said. “It wasn’t one thing that put it over the top – it was a combination of things and having all of the basics covered.”
University of Tennessee scientists have been looking at higher-yielding soybean research, including individual characteristics such as row spacings, maturity selections, planting dates and others. The study began in 2014 and is continuing in 2016.
Test plots in the study at the University of Tennessee’s AgResearch and Education Center at Milan are irrigated under the MOIST system, have high levels of P and K and the soil Ph tests in the low 6.0 range.
“We planted in May; we could not get into that April window because of equipment and some other issues,” she noted. “We try to make it at least by the 10th of May.”
Row spacings included a wide row vs. a narrow row – 30 vs. 15, they included a twin-row configuration along with their version of a skip-row planting pattern (accomplished by shutting off the third-row unit across the planter.)
The researchers experimented with 100,000 and 140,000 seeds per acre planting rates, avoiding higher planting rates and staying closer to the recommendations offered by the seed companies for most of their varieties.
Poultry litter not an option
They also applied nitrogen. “We didn’t have poultry litter as an option, but we looked at adding commercial nitrogen. We were really shooting for maximum yield so we put 150 pounds of nitrogen on, splitting it at R1 and R3.
“We planted two good varieties – AG 4632 and P47T36 – and those have been winners in some of the yield contests. We also threw Cobra in there. We sprayed the small beans and burned the tops to force more branching and maybe some extra pods.”
Narrowing the row spacings appeared to give the researchers a six-bushel per acre yield increase when all other factors were kept constant.
The higher seeding rate did out-yield the lower by about 2.2 bushels per acre, “which was enough to offset the higher seed cost,” said Dr. McClure.
“Nitrogen increased our yield on average about 4.6 bushels per acre,” she said. “If you do the math, the cost of the nitrogen is more than you will make on the higher yield with $9- and $10-per-bushel soybeans.”
Applying Cobra over the top of the small soybeans did not produce an economic return, the researchers said.
“We averaged between 80 and 90 bushels per acre so we did not get to the 100-bushel mark,” she said. “We had wet springs in 2014 and 2015, and lack of drainage may have been a factor. Planting in April might have also added a few more bushels to our production.”
For more information on the field day, visit www.milan.tennessee.edu