“Does hard ground have an iron and diesel deficiency? Hard ground has a nitrate deficiency.”
Dale Strickler asked attendees how to have healthy soils at a recent Land O’Lakes SUSTAIN event in Greensburg, Kansas. An agronomist with Green Cover Seed, Strickler said the main role soil serves for plants is to hold water and nutrients.
“First of all, get water into the ground. Reduce the evaporation, the amount that’s leaving the ground,” Strickler said. “Improve the capacity of the soil to hold the water for longer periods of time, increase the root depth and then increase the efficiency of the roots to extract the water from the soils.”
In other words, “get it in, keep it in and get it out.”
According to Strickler of Colony, Kansas, something went wrong with agriculture 4,000 years ago. Someone came up with the concept of a plow.
“We got on this road to tillage,” he said. “When you look at a tilled field—the water is going to run out and it does for about five minutes and the soil surface seals over.
Ground cover and run off are directly related to one another, and the more tillage you do the less infiltration you have.”
“That’s still a shock to a lot of people, but if you look and observe you always see water standing on tilled fields,” Strickler said. “You don’t see water standing on no-till fields.”
Strickler, who also operates Diversified Seed, has heard of farmers who have continual issues with hard ground. One farmer bales up stalks out of his fields and has trouble with his ground getting too hard. But he’s removing the best part.
“He runs a deep ripper out there and runs another to smooth. Repeat that process,” he said.
Strickler said the stalks and leftover crop residue help with water infiltration into the soil. Keeping the soil covered helps it stay softer and not pack as much.
“Why wouldn’t you take care of it if it would give you that much infiltration?” Strickler said.
Mulch can also do some other things, and if you don’t have enough mulch, Strickler said, “make more.”
“How do you make more residue?” he said. “That’s where cover crops come in.”
Cover crop strategy
Some farmers hesitate on using cover crops because of the amount of moisture they use.
“All growing plants will use moisture, but how effective is bare soil in storing moisture?” Strickler said.
If the soil is able to hold the water and not lose it, then it is capable of holding water for a long time. One of the benefits of cover crops is that they can be used to manipulate moisture-robbing weed pressure.
By using a high nitrogen cover crop, the residue left behind becomes important for the next crop in the rotation. A crop like soybeans, for example, can sequester nitrogen from the residue and the soil that’s been left over. Another crop that leaves behind a lot of beneficial residue is sorghum sudan.
“That can generate a lot of carbon, a lot of organic matter and a lot of cover,” Strickler said.
Biology can also help fuel water infiltration.
“You can get earthworms, dung beetles, all these critters to burrow in the soil and you can increase infiltration,” he said.
Soil microbes need fed and infiltration can help distribute nutrients where they need to be. Strickler compared it to feeding ruminant livestock. If the microbes in the rumen aren’t fed the proper diet, the animal likely won’t survive.
“What have we fed our soils for 150 years? Nothing but straw and occasionally some sorghum stalks,” Strickler said. “Will any of that sustain a ruminant animal? Because it won’t sustain microbes.”
According to Strickler, drought tolerance is the ability of a soil to supply water to a plant during a drought, and this is directly related to the biomass of that stalk.
“Finding night crawlers (in soil) are a pretty good indication of microbial biomass because it might be what a night crawler needs,” he said. “They need microbes.”
Boosting organic matter
So how do you get more organic matter into the soil? Strickler said he was told in a college level soils class that increasing organic matter was nearly impossible. But he’s found his own way since then.
“You can raise soil organic matter if you understand the principles by which soil organic matter is raised,” Strickler said. “If you want to create the ideal soil, you have a soil that can hold water and oxygen and nutrients and supply at the same time.”
Most soils can either supply air or water, but not both at the same time. The only way to do both is by having openings in the soil for those two things to infiltrate. For example the tunnels left behind by earthworms or the voids where cover crops like turnips or other root vegetables grew.
“All those little surfaces—microbes and minerals and water—are stored,” he said.
Strickler said some farmers struggle with how to get roots to go deeper into the soil. Some think subsoiling or plowing is the answer. Research has shown subsoiling doesn’t help, but instead leads to a decrease in yields. Strickler said in the 1880s Kansas State University started experimenting with subsoiling.
“There was a bulletin from 1895 that says in our trials we have seen a 15 percent reduction in yield from subsoiling,” Strickler said. “That was 120 years ago. In the 1950s, they came out with another one saying 60 years of research we have found no advantage to subsoiling.”
He’s still perplexed.
“This is something we’ve known for 120 years and people are still selling plows,” Strickler said. “People are still buying the things. They’re still using the things.”
It does make some sense because the ground is hard, and they think busting it up will help alleviate the problem. But actually the soil needs carbon dioxide and organic matter to help bust the hard pan.
“That’s the solution to compaction right there,” Strickler said. “It’s not steel and it’s not diesel. It’s microbes and organic.”
When the soil is “ripped” it’s actually making it regress.
“You’re burning up the food source for the microbes,” he said.
Boosting oxygen
Roots have to have oxygen in the soil, and by getting more oxygen into the soil, the microbes can thrive.
“There are things that we don’t understand about the function of soil microbes in that soil,” Strickler said. “But we do know how you get more of it.”
Keeping organic matter in the soil, having surface residue and keeping the soil surface covered is crucial. The biggest contributor to soil organic matter is soil microbes. When soil microbes are fed, roots benefit.
“Feed microbes like you would feed cattle,” Strickler said.
Kylene Scott can be reached at 620-227-1804 or [email protected].
