In Arkansas and Louisiana, the yearly effort to test Extension soybean recommendations in the real world is known as a “verification” program. In Mississippi, the program is known as SMART: Soybean Management by Application of Research and Technology.
Started in 1983, Arkansas' soybean verification program is the grandfather of the three. Mississippi's program began in 1992 and was followed by the LSU AgCenter's in 1994.
However, it was the programs' recent history — 2000 through 2004 — that David Lanclos focused on when he greeted a full house at the annual Tri-State Soybean Forum in Delhi, La., on Jan. 6. The Louisiana Extension soybean specialist said all the verification programs are funded by respective state soybean promotion boards.
“None of the states could run these programs without the promotion boards' support,” said Lanclos.
Since inception, the programs' number of fields (Arkansas, Louisiana, and Mississippi) is 400, 120, and 301.
For the last five years, the state soybean yield averages are 33.7, 31, and 32.6. For the same period, verification fields averaged 46.4, 45.2, and 47.2.
“That's a tremendous increase in yield over the state averages. The good news is we're running neck-and-neck with Midwest averages. This shows our fields are productive and we can grow soybeans profitably and well.”
Lanclos emphasized the fields used are “real-life, on producer land. We get a lot of questions about these verification fields every year. ‘Why do the verification fields do so much better? This must not be real-life.’
“I can promise you it is. In Louisiana we allow the producer to choose the field. We have no say-so in that. In many cases, they actually give us their more difficult fields to work in.
“We choose a variety with the producer. He makes the final decision, though. The key to the program is we're there weekly making scientifically-based recommendations.”
What are some other factors that go into these programs?
- Proper fertility
- Maturity group and variety selection
- Plant population
- Planting date
- Intense IPM strategy.
“What do I mean by intense IPM strategy? Insect, disease and weed spraying applications and season-long scouting. From the time the beans come up to when you drive the combine into the field, you need to be on top of the situation.”
Over the last five years, 292 fields covering some 15,000 acres were analyzed. “We had some variability in that because not every field had all the parameters that could be evaluated.”
Lanclos didn't include Group 3s or 6s in his analysis. “We have tremendous interest in the early production systems. But we didn't have enough of a sample to justify exposing that data in this type of presentation.”
In Arkansas, irrigated fields had a tremendous advantage over dryland. In Louisiana, the difference hasn't been as pronounced.
“That's probably because Louisiana typically receives more rainfall than Arkansas and Mississippi. Mississippi showed a clear difference — irrigation obviously pays there.”
Overall, irrigated verification acreage in the tri-state region saw a 12.2 bushel increase over dryland.
“There's a lot of interest in this around the Mid-South. Do I need to raise beds? Do they give me an advantage?”
Overall, the tri-state area produces up to 1.5 bushels per acre more on raised beds. But 1.5 bushels “over 800 or 1,000 acres becomes significant.”
In Arkansas, raised beds under irrigation had the best showing. The same was true for Louisiana. In Mississippi, the superior systems were flat/irrigated followed by raised/irrigated.
“Bottom line is irrigated systems do better whether they're on raised or flat ground.”
Yield by maturity group
For this category Lanclos focused on 269 fields of Group 4s and 5s. In Arkansas, there was a bit of an advantage with the 4s. In Louisiana, 5s did better. Across the tri-state, 5s outyielded 4s by about 4.5 bushels per acre.
Date of planting
“This is where it gets fun. We start out at March 16 through March 31. We end planting dates at June 16.” The total sample size is about 280 fields.
In Arkansas, there was a clear distinction in terms of where to plant and maximize yield: somewhere at the end of April into May. “Louisiana and Mississippi followed the same pattern, although Louisiana took a big dip in May for some reason. However, the trend-line shows the early planting system is definitely productive when talking about maximizing yield.”
“When I came on board four years ago, there were a lot of questions. ‘How long can I plant 4s? How long can I extend the planting season?’
“With the 4s, there's a little bit larger window. In Louisiana, somewhere around that May 1 through May 15 is when you need to stop planting them. After that, yields drop off significantly.”
While individual state data is extremely variable Lanclos said maximizing yields still indicates the best planting window is in early April.
If you wait to plant 5s, yield is lost.
“One of the interesting things I've found with 5s is what the (Asian soybean rust) sentinel plots have taught. The later maturity groups can be pushed a bit harder.
“In Louisiana, there isn't an exact date we can point to and push it three weeks earlier than when we usually plant. But I do believe there's a week to 10-day — perhaps 14-day — window that we can push.
“In Arkansas, it's obvious that Group 5 yields are maximized with planting dates May 1 through May 16.”
For the tri-state region taken together, Group 4 and 5 yields were maximized when planting began in mid-April. When analyzed separately, yields for both groups were still best when planting occurred between April 16 and April 30.
Currently, Arkansas and Mississippi are doing much research on plant populations. The aim is to try and save dollars by reducing plant populations slightly and still maintain yields.
“This may be a place producers can reduce input costs.”
In the data cited, final populations — not planted populations — are tabulated. “Considering 80 percent germ, you still need to plant a lot more than the final plant population. We went to 81,000 as the low parameter. The top was 160,000-plus.”
Arkansas yields were best when plant populations were from 100,000 to 140,000 seed per acre.
“That's a big range — not something we saw in Louisiana and Mississippi, where maximum yields were obtained at 100,000 to 120,000 plant populations. You need to plant 150,000 to 160,000 seed to get that 120,000 plant population.
“It's interesting that increasing seeding rates past 140,000 shows a trend of losing yield.”
“This is for the tri-state region alone. There isn't a lot of variability when it comes to changing row-spacing with 4s or 5s. Across the three states, the maximum yield was obtained in 12-inch to 25-inch row spacings.
“As far as row spacing/bed interaction, we went 7-inch to 19-inch, 19-inch to 25-inch, and 25-inch plus. This is a bit difficult to explain, but it appears that for the tri-state perspective, a raised bed has an advantage. That advantage isn't as strong in the 25-inch-plus range.”
Because this data is for irrigated fields only, the sample size dropped dramatically to 184 fields.
In Arkansas, yields were best with 19-inch to 25-inch row spacings. In Louisiana, yields were maxed in 7-inch to 12-inch rows. Mississippi did best with 19-inch to 25-inch row spacings.
Across the tri-state area, 19-inch to 25-inch row spacings were superior. In rows wider than 25 inches yield was lost.
“In Arkansas, if you're non-irrigated, the 7-inch to 12-inch row spacings are superior. In Louisiana, the best is 12-inch to 19-inch. Mississippi does best with 25-inch to 32-inch row spacings. Across the tri-state, the best is 32-inches-plus.