Tag Archives: soil

As devastating images of the 2019 Midwest floods fade from view, an insidious and longer-term problem is emerging across its vast plains: The loss of topsoil that much of the nation’s food supply relies on.

Today, Midwest farmers are facing millions of bushels of damaged crops such as soybean and corn. This spring’s heavy rains have already caused record flooding, which could continue into May and June, and some government officials have said it could take farmers years to recover.

Long after the rains stop, floodwaters continue to impact soil’s physical, chemical and biological properties that all plants rely on for proper growth. Just as very wet soils would prevent a homeowner from tending his or her garden, large amounts of rainfall prevent farmers from entering a wet field with machinery. Flooding can also drain nutrients out of the soil that are necessary for plant growth as well as reduce oxygen needed for plant roots to breathe, and gather water and nutrients.

As scientists who have a combined 80 years of experience studying soil processes, we see clearly that many long-term problems farmers face from floodwaters are steeped in the soil. This leads us to conclude that farmers may need to take far more active measures to manage soil health in the future as weather changes occur more drastically due to climate change and other factors.

Here are some of the perils with flooded farmland that can affect the nation’s food supply.

Suffocating soil

When soil is saturated by excessive flooding, soil pores are completely filled with water and have little to no oxygen present. Much like humans, plants need oxygen to survive, with the gas taken into plants via leaves and roots. Also identical to humans, plants – such as farm crops – can’t breathe underwater.

Essentially, excess and prolonged flooding kills plant roots because they can’t breathe. Dead plant roots in turn lead to death of aboveground plant, or crop, growth.

Another impact of flooding is compacted soil. This often occurs when heavy machinery is run over wet or saturated farmland. When soils become compacted, future root growth and oxygen supply are limited. Thus, severe flooding can delay or even prevent planting for the entire growing season, causing significant financial loss to farmers.

Loss of soil nutrients

When flooding events occur, such as overwatering your garden or as with the 2019 Midwest flooding, excess water can flush nutrients out of the soil. This happens by water running offsite, leaching into and draining through the ground, or even through the conversion of nutrients from a form that plants can utilize to a gaseous form that is lost from the soil to the atmosphere.

Regardless of whether you are a backyard gardener or large-scale farmer, these conditions can lead to delays in crop planting, reduced crop yields, lower nutritive value in crops and increased costs in terms of extra fertilizers used. There is also the increased stress within the farming community – or for you, the backyard gardener who couldn’t plant over the weekend due to excess rainfall. This ultimately increases the risk of not producing ample food over time.

Small microbial changes have big effects

Flooding on grand scales causes soils to become water-saturated for longer than normal periods of time. This, in turn, affects soil microorganisms that are beneficial for nutrient cycling.

Flooded soils may encounter problems caused by the loss of a specific soil microorganism, arbuscular mycorrhizae fungi. These fungi colonize root systems in about 90% to 95% of all plants on Earth in a mutually beneficial relationship.

The fungi receive energy in the form of carbon from the plant. As the fungi extend thread-like tendrils into the soil to scavenge for nutrients, they create a zone where nutrients can be taken up more easily by the plant. This, in turn, benefits nutrient uptake and nutritive value of crops.

When microbial activity is interrupted, nutrients don’t ebb and flow within soils in the way that is needed for proper crop growth. Crops grown in previously flooded fields may be affected due to the absence of a microbial community that is essential for maintaining proper plant growth.

The current Midwest flooding has far-reaching effects on soil health that may last many years. Recovering from these types of extreme events will likely require active management of soil to counteract the negative long-term effects of flooding. This may include the adoption of conservation systems that include the use of cover crops, no-till or reduced-till systems, and the use of perennials grasses, to name few. These types of systems may allow for better soil drainage and thus lessen flooding severity in soils.

Farmers have the ability to perform these management practices, but only if they can afford to convert over to these new systems; not all farmers are that fortunate. Until improvements in management practices are resolved, future flooding will likely continue to leave large numbers of Midwest fields vulnerable to producing lower crop yields or no crop at all.

Loran Steinlage has a more permanent solution to heavy downpours than tile drain. He’s improving his soil structure. By increasing soil carbon he’s built resilient soil that drains well and stores water for droughts.

His financial returns are highest on the fields with the most diverse cover crops, cash crops and relay crops. By “relay,” he means growing a second crop (soybeans, rye or wheat) in the same growing season.

This diversified soil allows microbes to retain and recycle nutrients, store nutrients and prevent erosion through winter while adding income from cover-crop seed. By comparison, a conventional crop rotation has a “brown winter season” vulnerable to nutrient and soil loss, and the death of beneficial soil microbes.

THE POOR FARM

Town elders once called Steinlage’s Fayette County, Iowa, farm “the poor farm,” an unproductive parcel until Loran’s father, Florian, bought it in 1968. Fifty years later, this self-described “po’ dirt farmer” (his comic term for conservation tillage) now speaks internationally on how his family transformed poor glacial till soil into resilient, productive soil. His clever tillage adaptations are nationally recognized by soil-health experts. Steinlage also works as a practical field engineer for DAWN/UndergroundAg.

He no-tills 750 acres of corn, soybeans, wheat, rye, malt barley and buckwheat near West Union, Iowa. Steinlage farms 25 glacial-till soil types, ranging “from gravel to peat in the same pass.”

Fast-forward through 26 years as a dairy, then continuous corn to the past 10 to 12 years of reduced/strip-till/no-till, interseeding and multispecies cover-crop mixes, and a relay crop of soybean, rye or wheat in the same field. His FLOLOfarms won the 2017 Iowa Environmental Award, and his name dominates soil-health forums and meetings. “I’ve never been conventional,” Steinlage said.

YIELD STABILITY

Soil resilience is Steinlage’s top priority. Why? Soil resilience brings yield stability despite precipitation extremes, said Jerry Hatfield, director of the USDA National Laboratory for Agriculture and the Environment, based in Ames, Iowa.

“We’re gearing for feast-or-famine weather patterns,” Steinlage said. “We’re building our soils with cover crops, diverse crop mixes and no-till. We’re erosion-proofing our soils. We had 21 inches of rain in one week the summer of 2017. The neighbors had runoff, but we did not.

“In 2012, we had a big rain the day after planting. I was worried about getting back in to spray the clovers (cover crop). That’s why I now band herbicide with the planter — to give the cash crops an edge.” The cost is about $6 per acre. He uses Acuron or combines acetochlor or metolachlor and atrazine. “If we don’t disturb the soil, we don’t have weed problems,” Steinlage added. He customized row cleaners that move residue but not soil.

After 10 years of these practices, a $15-per-acre cover-crop seed investment and diverse species in the same field, his corn yields are 15 bushels per acre ahead of any other fields he farms.

The result of these practices is more soil carbon, the fuel for crops and nutrient recycling. “Liquid carbon is the ‘underground currency’ that feeds soil microbes,” Steinlage said. He explained carbon is what microbes exchange for more plant-available nutrients, which they recycle from residue. (See “The Underground Economy” sidebar farther down.)

The per-acre revenue for ground planted to cereal rye cover crops, cash soybeans and buckwheat cover crops is a minimum of $660, he said. “We can easily double that; I just don’t like to promise the moon.”

In 2018, he switched to non-GMO soybeans to capture an additional $60,000 in IP (identity preserved) premiums ($2 per bushel non-GMO premium) and $50,000 in lower seed costs.

Steinlage tailors cover crops to the crop that will follow them. “You want all four plant families in a mix (warm-season broadleafs and grasses, and cool-season broadleafs and grasses),” Steinlage said. For continuous corn, he plants into live N-rich (nitrogen) legumes such as clovers and vetch. On ground going to soybeans, he mixes annual ryegrass with brassicas.

On a test field, Steinlage interseeds a varying “jungle mix” of 17-species combinations of tillage radish, dwarf Essex rape, vetch, buckwheat, phacelia, flax, oats, several clovers and more, depending on the field and rotation. This test field has 15-bushel higher yields than his others on some of the poorest county soils.

GIFTED WITH A WRENCH

Known far and wide for his mechanical creativity, Steinlage has built and modified at least eight cover-crop interseeders in the past 10 years.

When he could afford to build from the ground up, he mounted a Montag dry fertilizer box on a Dalton custom bar, adding customized Dawn DuoSeed row units with a seed sensor that precisely monitors cover-crop seeding rates. This feature is now standard on Dawn’s new DuoSeed Pro. Steinlage’s interseeder also has Precision Planting monitoring, seed firmers and a wide drop tube for larger seeds. He designed his own row cleaners and rollers. This rig drills fertilizer, soybeans and fall cover-crop seeds, and can sidedress urea at V4 on the same pass based on soil-nitrate test results.

The goal is to have permanent cover and roots between corn and soybean rows. “We were there in 2012, but Mother Nature is a formidable foe,” Steinlage said. “Since 2012, our ‘yo-yo’ springs have killed most covers in March.”

A close friend of Steinlage’s describes him: “The Steinlage family’s on the forefront of redefining the future of crop production and soil-health management, while still recognizing that we need to be profitable,” said Jacob Bolson, Hubbard, Iowa. “With the economic, regulatory, public perception and environmental constraints facing farmers, we must be willing to challenge the norm and take strategic risks.”

PLANTING GREEN

After planting corn or soybeans, Steinlage used to crimp or roll cover crops to terminate them or slow them down … or he just leaves them if there’s no moisture shortage. Why? Because cover crops crowd out weeds and store nutrients that otherwise leach in downpours. Cereal rye’s allelopathy is nature’s herbicide. Cover crops can also add to soils’ carbon levels.

He experiments a lot, including trials with Bob Recker, a retired John Deere engineer and founder of Cedar Valley Innovation, in Waterloo, Iowa. One of many successful tests was 60-inch corn rows with cover-crop mixes in between the rows. Higher corn populations (54,000 per acre) is equal to conventional populations in 30-inch rows; and yields were 230 bushels per acre. The wider rows allow more sunlight to boost corn yields.

Steinlage shut off Rows 2, 5, 8 and 11 on his 12-row planter resulting in a 2-row, skip-1 pattern for this 1-acre plot. He interseeded a mix of buckwheat, oilseed radish, annual ryegrass and dwarf Essex rape at corn’s V4 stage. With no yield hit to these “skipped rows,” he’ll now add livestock to the mix.

“Loran has a unique willingness to experiment with widely varying approaches, accepts that some things will not work and, most importantly, is very open in sharing his results and learning,” Recker said.

Steinlage has proven that no-till soil is 10 to 15 degrees F warmer than conventionally tilled soil using a $200 Flir thermal camera and temperature sensors. (The University of Minnesota and North Dakota State University have similar findings.) Underground microbial activity warms the soil, insulating germinating corn against broad temperature swings.

PIE DROPS

Most of Steinlage’s crop nutrients come from semicomposted dairy manure (traded for crop residue) and N-rich cover crops. Steinlage will borrow sheep to graze his interseeded cover crops in exchange for “Pie Drops” (his version of Y Drops). Free fertility and weed control harken back to farming in the 1950s, he said.

The Steinlages have been 100% controlled traffic since 2009. Equipment is 30 feet wide on 120-inch centers, limiting soil compaction. “I think aerial drone footage will sell the concept: Aerial photos make compaction’s impact so evident,” he said.

The family has weathered far more than its share of family health crises and accidents. When asked about how stress has swayed his farming decisions, Steinlage said he uses the 100-year rule: “Will this decision be important 100 years from now?” If you’re talking about resilient soil, the answer is yes.