Get Back To The Good Days With Small Grains

(Agrinews.com) – ALBERT LEA, Minn. — Sarah Carlson’s motto is “Don’t Farm Naked.”

The Practical Farmers of Iowa Midwest cover crop director is another voice speaking up for keeping soil covered as much of the year as possible. She spoke at the Freeborn Area Soil Health Team Soil Health Winter Workshop on Jan. 26.

Leaky crops

For the last 100 years, Carlson said, the percentage of acres planted to corn in Iowa has remained about the same, about 60 percent. The biggest change involves small grains. Acres planted with them have declined significantly, down to less than 1 percent of all cropland in Iowa, with Minnesota and other Midwest states seeing similar declines.

The problem with this, in Carlson’s words, is that corn and soybeans are “leaky.” Because they grow in summer, if nothing else is planted in between, the environment is ripe for nutrient leaching with precipitation. Nitrates and other nutrients wind up in tile lines, and flow into bodies of water.

This is why water quality issues in Iowa and Minnesota have gotten to the point that they have, with legislatures debating how to address them. Plus, the average cost loss of erosion for a farmer is $6.06 per ton.

Small grains provide an answer, since they grow in spring and winter. According to Carlson, 52 percent of central Iowa’s precipitation comes between October and May.

“Crops pull water out of the soil with the nutrients,” Carlson said, “but with no plants growing, if there’s a warm-up during winter, we will have nitrogen losses.”

The high organic matter soils in Minnesota and Iowa especially need this attention. Carlson encouraged running tile line tests to check for nitrate levels.

“It’s a big wake-up,” she said.

Multiple benefits

Carlson, who participated in 75 field days last year, said she’s noticed the high interest in soil health, as farmers look to fight back against water quality problems.

She cited a farmer from Wright County, Iowa, who found out in 2011 that nitrates in his tile lines were above drinking water standards. He had already been using best practices in fertilizer management, but hadn’t addressed how nitrogen was leaving the system through leaching and erosion. He tried flying on cover crops the next year into standing corn and soybeans and got an immediate result from the next tile line test.

Of the three common types of cover crops — small grains, brassica and legumes — Carlson encourages starting with small grains and progressing to adding brassica to the mix. She discouraged using legumes, which include plants like hairy vetch and lentils, unless they can be seeded early. There isn’t enough heat units during winter for them to grow between corn and soybeans.

Cool season grasses and small grains produce an infusion of biomass that provides weed control. Carlson said that farmer Jeremy Gustafson of Boone, Iowa, was able to eliminate two weed control passes in 2016. She suggested, with ryegrass, rolling it down around planting time to solidify the weed control mat.

For livestock producers, cover crops also provide a feed source. In general, Carlson said, cattle will eat more corn stalks along with green material. Plus, calves born on green mats rather than bare dirt are cleaner, which bodes well for their health in the first months of their lives.

Back to diversity

The multiple-crop rotations that were more common in the past, according to Carlson, bring yield benefits in addition to cleaning up water. She encouraged producers to plant more than the common corn-soybean rotation, citing research from the United Kingdom that showed globally, shorted rotations such as corn-soybean could compromise 7-36 percent of corn yield and 8-20 percent of soybean yield.

Carlson was part of a strip trial study over eight years measuring yield in corn and soybeans after rye planting. The majority of the time, there was no change in corn yield. Three locations had a reduction in yield in 2009, which Carlson attributed to improper use of Liberty herbicide. In 2016, two locations had an increase in corn yield in strips with rye over those without. The soybean trials had even more increases in yield with rye planted before.

Perhaps what is aiding the yield increase is a benefit to plant health. Iowa State University soybean researcher Leonor Leandro has seen that soybeans grown as part of a three-year rotation including a small grain were healthier than a two-year rotation, with fewer instances of sudden death syndrome.

Crop diversity provides returns in decreased pesticide, herbicide and fertilizer use as well. Carlson said that in a two-year crop rotation, pesticide use was six times higher than in a three-year rotation that included a small grain.

Corn grown after green manure crops requires 88 percent less fertilizer, according to research from Iowa State University’s Matt Liebman done since 2006. Beyond just providing soil protection, green manure crops, which include legumes, produce nitrogen for the soil. Carlson said that kind of system is more advanced than simply growing rye.

Possibilities

Cover crops don’t generate a ton of extra cash, but that may be changing. Practical Farmers of Iowa is working on a cost-share program that would encourage corn and soybean farmers to grow small grains, in turn for sharing farmers’ stories with food and beverage companies to help persuade them to buy small grains. This is a fairly new program, so Carlson did not have much to report. Meanwhile, she mentioned that Grain Millers, Inc., purchases feed grade oats.