Charles Stichler, Extension agronomist in Uvalde, Texas, sums up his philosophy about conservation tillage this way: “The main thing is to keep the main thing the main thing.”
So, what's the main thing with conservation tillage? Time was, soil stewardship may have claimed the top spot on anyone's list of why he cut back on cultivation.
These days, however, considering the sorry state of commodity prices and the seemingly never-ending jump in production costs, simple economics take precedence.
“Profitability is the reason for reduced tillage,” Stichler said recently at a Monsanto-sponsored “warm-up” seminar, a prelude to the 6th annual Cotton and Rice Conservation Tillage Conference in Houston.
The main thing, he said, means farmers find the best system for their specific farms. “Not everyone in this room wears the same size shoe. Farms are just as different as feet.
“Conditions in the Lower Rio Grande Valley vary widely from those in the Blacklands, which varies from the High Plains, etc. Rolling Plains soils may be different in San Angelo than they are in Vernon. And El Paso farmers have drier soils. Unique situations change the way we treat soil.”
That means farmers have to take their unique situations, soil types, rainfall patterns, and crop selections, into account as they develop tillage programs, Stichler said. Different crops offer different challenges for conservation tillage.
“Corn may be the easiest to start in reduced tillage,” Stichler said. “It's a forgiving crop. We can plant seed more than 2 inches deep, and we can plant early.”
He said farmers have a “lot of herbicide choices, including Roundup Ready and Liberty Link systems. “Corn residue is easy to manage since the corn plant dies when it is mature and degrades by spring planting time.”
Sorghum is less forgiving and not as easy to work into a reduced-tillage program, but it's still viable.
“We plant sorghum late and we plant seed shallower than we do corn. At planting time soils have started to warm up and dry out. With smaller seed, stands are more difficult to obtain.”
Herbicide choices for sorghum are more limited, too, especially for grasses and hard-to-kill perennials. Many of the herbicides also require rain or irrigation to activate.
Stichler recommends farmers who use sorghum in their no-till systems should invest in a hooded sprayer to assure adequate weed control. Growers have no transgenic sorghum varieties available, so they have to take care of weeds with traditional methods, he said.
Killing the crop early also makes residue easier to handle for the next crop, Stichler said. “Kill it either just before harvest or as soon after as possible.
“Before harvest is best.”
He said sorghum root crowns and stubble resist decay and stay tough into spring. “Shredding the stalks will put residue on the surface and provide badly needed mulch.”
Cotton provides an even greater stand challenge than grain sorghum. “We plant late, often into dry soils and deal with a number of seedling diseases. More fungi are active in the emergence zone.”
Stichler said cotton seedlings have difficulty pushing through soil crust, so packing rains may delay a stand. Also, the cost of transgenic seed has encouraged farmers to reduce plant populations, which also could result in stand problems.
“But those transgenics have made weed control much easier in reduced tillage systems. Farmers have a lot of possibilities with herbicide tolerant varieties. But they still need a hooded sprayer and pre-emergence herbicides. Growers should avoid using the same soil-applied herbicides over and over, however.”
Stichler says a lightly tilled, narrow row, may improve germination and stand. Occasionally, fall tillage, one disk pass or one run with a field cultivator, “will loosen up the soil crust and make it less firm at planting.”
Stichler said growers must kill cotton stalks after harvest, especially with the Boll Weevil Eradication Program in place.
“Farmers have to kill the root to prevent re-growth that hosts weevils,” he said. He recommends 2,4-D, applied right behind the stripper or header. Shred and spray a 12-inch band over the row.
“If growers wait until leaves emerge, control is more difficult.”
Stichler said cover crops may pull more moisture out of the soil than they save. “We usually get fall rains and then little else before spring. Cover crops do the most good in the fall, when rains are heaviest and we need erosion control.”
He says one compromise might be to plant one row of a cover crop in the bottom of the furrow. “The cover provides protection from wind and water erosion.”
He said controlling winter weeds also poses problems in a cover crop.
Stichler recommends farmers plant on a bed, if possible. “But in rolling land or furrow-irrigated fields water erosion may become added to drainage problems. No-till may be a good bet in these situations. A low, rolling bed might work, too.”
Beds hold water and farmers can knock off part of the bed to find adequate moisture to plant. Stichler suggests farmers pull up the bed in the fall and then leave it alone. Remaking old beds may be adequate.
He says limited tillage may be beneficial in some soils, especially heavy clays where “soils set up. Strip tillage units may play a role in these conditions. With most other soils, however, we see little advantage with tillage.”
Closing wheels may improve crop stands, especially in dry soils planted no-till. “A spiked closing wheel destroys the side-wall compaction and improves seedling emergence,” he said.
Conservation tillage farmers also need to evaluate fertility timing and placement. “Planting in the same place year after year may result in depletion of available nutrients; so accurate fertilizer placement is crucial for good plant growth.”
With nitrogen, move placement site over enough to prevent root burn and watch for nutrient stratification. “Nitrogen should be placed 2 inches to the side and 2 inches below the seed. That placement puts nitrogen where young plants can take it up.”
Conservation tillage may require more nitrogen the first few years.
Pop-up fertilizer may benefit corn and sorghum, Stichler said, but not cotton. “Cotton needs zinc, however.”
Limiting compaction remains crucial, even with reduced-tillage systems. Stichler says a “controlled traffic pattern,” leaves the growing zone open. He also said reduced-till soils will be firm, but not necessarily compacted.
Weed control in conservation tillage demands attention. Stichler recommends killing in-season weeds as early as possible.
“Do not let grass compete with the crop,” he said. “Use a variety of herbicides and don't let weeds go to seed. Kill winter weeds before they can compete.”
Stichler said farmers must pay attention to their fields to determine what works and what doesn't in each crop. “They should think about everything they do and ask why they do it. They have to forget what their neighbors say about conservation tillage, and they can't expect perfection on their first attempt.”