Crop rotation is an important part of a no-till production system
"Planting a double crop once in a while is not a crop rotation," Godsey said.
By Doug Rich
The second annual No-till Oklahoma conference was held in Oklahoma City, Okla., on Feb. 9 and 10. Nearly 300 people attended the meeting to learn about no-till farming from Extension specialists and actual producers.
Chad Godsey, an assistant professor in the Department of Plant and Soil Science at Oklahoma State University (OSU), began the meeting with some statistics from a recent no-till survey in Oklahoma. According to the survey, 33 percent of the wheat in Oklahoma is planted no-till. Soybeans lead the way with 77 percent planted no-till followed by corn at 68 percent, grain sorghum at 60 percent, and cotton at 29 percent.
According to the survey, soil fertility is one of the main problems that Oklahoma producers have with no-till farming. This was the first topic on the agenda at the No-till Oklahoma conference. Lloyd Murdock, a professor in the Plant and Soil Science Department at the University of Kentucky, gave some tips on soil sampling in no-till fields.
Murdock said that, with no-till, all of the fertilizer is placed on the surface and not mixed in mechanically. In this situation, how deep should a producer go for soil tests? Murdock suggested that sampling soil at a depth of four inches is sufficient.
"Even with conservation tillage, anything below four inches is not really necessary," Murdock said.
According to Murdock, a single soil sample should not represent more than 20 acres. Field slope, drainage, and cropping history should be taken into account, also.
As producers convert to no-till, they wonder if their fields will yield as well with all of the fertility applied on the surface. Murdock said that once the soil in those first few inches is built up, it is as good as mixing it in.
"Over time, yields will be just as good on no-till as the guy who conventionally tills and, when moisture is short, it will be better," Murdock said.
When farmers in Kentucky began converting to no-till, Murdock said they recommended a little more nitrogen the first few years, but he is not sure that is needed anymore.
Murdock said a broadcast application is the least efficient way to apply fertilizer. A dribble application is better, but the best way is to inject the fertilizer. Farm below the mulch level whenever possible.
Brian Arnall, an Extension specialist at Oklahoma State University, said no-till farming can reduce the risk of losing nitrogen. No-till reduces water movement and can reduce leaching of nitrogen fertilizer. Arnall said whether or not a producer needs more nitrogen in the first three to five years of no-till or less nitrogen after five years of no-till depends on a variety of factors.
Arnall said applying nitrogen below the crop residue is the best option if at all possible. This method reduces immobilization of the nitrogen fertilizer.
If a producer switches to four-inch soil samples, Arnall said to be sure to let the lab know when the samples are sent in for testing. Arnall also said if a producer is using a legume as a cover crop to account for the nitrogen fixed in the soil by these crops.
Weed control is another concern for no-till farmers. Curtis Thompson, State Extension weed scientist at Kansas State University, said that no-till tends to help control large-seeded broadleaf type weeds like velvetleaf, cocklebur, and morningglory. However, no-till tends to favor development of small seeded weeds like crabgrass, foxtails, and pigweeds.
"When fuel was cheap and herbicides were more expensive, it was hard to convince people that no-till was the way to go," Thompson said. "But as fuel prices have increased and herbicides prices have declined, it has become a lot more appealing."
Crop rotations can help with overall weed management in no-till. Thompson said the diversity of crops allows the use of a more integrated approach with herbicide selection and timing of herbicide applications. The use of grass and broadleaf crops in the rotation is helpful because it allows the producer to diversify his herbicide products.
A crop rotation of Roundup Ready corn, Roundup Ready soybeans, Roundup Ready corn followed by Roundup Ready soybeans is not good, according to Thompson. An efficient crop rotation should incorporate some conventional herbicides.
"Glyphosate is an effective product, but tolerant weeds tend to increase when it is used over and over in a crop rotation," Thompson said.
Glyphosate is effective and residual damage to subsequent crops is never a problem but tolerant weeds are on the rise. Weeds found to be glyphosate tolerant include yellow nutsedge, morningglory, velvetleaf, prairiecup grass, johnsongrass and kochia.
Thompson suggested using glyphosate by itself sparingly. Do not use reduced rates. Thompson tank mixtures may delay development of resistance to glyphosate.
When double-cropping behind wheat, Thompson said to control the weeds in the wheat cycle.
"Winter annual weeds are young and more susceptible to herbicide control in the fall," Thompson said. "Fall application can reduce the need for a burndown in the spring."
One of the advantages of no-till is the ability to do more crop rotation. Chad Godsey said moisture, government programs and crop insurance usually dictate a producer's crop decisions. No-till improves moisture retention, which increases the opportunity for intensive crop rations.
"Crop rotation is field specific and farm specific," Godsey said.
The normal crop rotation in Oklahoma is three crops in two years. Oklahoma, particularly eastern Oklahoma, has the opportunity and ability to grow several different crops. Water is money to farmers; and no-till stores and makes available considerably more water.
"Planting a double crop once in a while is not a crop rotation," Godsey said. "You need to lengthen the period of time between similar crops."
There are several different types of crop rotation. A simple rotation would be wheat-corn system. A simple rotation with perennial sequence would be corn-soybean-corn-soybean-corn-soybean-alfalfa. A compound rotation is two simple rotations put together. An example of a complex rotation is wheat-corn-sunflower-grain sorghum-soybeans. Godsey said some no-till producers are going to stacked rotations such as wheat-wheat, corn-corn, and soybeans-soybeans.
Godsey said to select crops for a rotation that are adapted to the local climate, that fit your specific management system and have a potential market or forage value.
Some crop rotations include a fallow period when no crop is grown. Godsey said a fallow period does not need to be any longer than necessary to achieve 80 to 100 percent of stored water capacity of the soil.
Brent Rendel, a producer from Miami County, Okla., said his goal is four crops in three years. Rendel has intensified his crop rotation with the addition of a no-till double crop. He has a four-year rotation that has wheat and summer fallow the first year, wheat and double-crop soybeans the second year, full-season soybeans the third year and grain sorghum the fourth year.
Oklahoma State University is working several demonstration plots where cover crops are being incorporated into the crop rotation. Silvano Abreu, a PhD student in the Department of Plant and Soil Science at OSU, outlined some of these rotations. OSU is looking at several of these rotations including wheat-cowpea-corn, wheat-cowpea-grain sorghum, and grain sorghum-Austrian winter pea-sunflower. Last March they began an intensive crop rotation study that will yield five crops in two years.
Abreu said cover crops help to break weed and disease cycles as well as fix nitrogen in the soil.
Grazing and no-till
Historically, Oklahoma has been known for its cattle production and not its no-till production, but there are some studies being done that combine the two elements.
"When you put a cow in the system, it makes it much more difficult," John Sij said. Sij is an agronomist with the Texas AgriLife Research in Vernon, Texas.
Grazing wheat is a very important business in west Texas. Sij said they have over 3 million acres of wheat planted in his area. Depending on the year, 50 to 80 percent of that wheat is grazed.
The condition at Vernon, Texas, includes frequent drought, high winds, high temperatures, and highly erodible soils. Sij said when it does rain, it tends to be intense. The goal of his research project was to identify fertility levels that maximize forage and beef yields as well as grain yields in no-till and conventional-till wheat-stocker production systems.
When comparing conventional tillage with no-till in the gain and grain system, Sij concluded that there was little to no difference in forage yields; there was a linear response in forage production to pre-plant nitrogen application; soil compaction may not be as much of a problem as once thought, but more work needs to be done; grain yields were not significantly different in three of the four years in the study; and there was improved infiltration, nutrient retention and water quality in the no-till dual-purpose wheat system.
Sij noted that in two out of the last three years, it was possible to turn cattle out on no-till fields two to three weeks earlier than on conventionally tilled fields.
Oklahoma has made great progress in its adoption of no-till farming methods. According to the no-till survey, 33 percent of the total crop acreage in the state is no-till. That compares very favorably with the national average of 27 percent.
"We have come a long way in a few years," Godsey said.
Doug Rich can be reached by phone at 785-749-5304 or by e-mail at firstname.lastname@example.org.