Renewable Farming

One slim benefit from drought-killed corn: Earlier start for recycling residue biologically

Advocates of fall-sprayed stalk residue digester products always encourage early application — before temps drop below 50 degrees. This season, central and western Iowans under near-drought conditions can get an earlier opportunity to spray lignin-munching bacteria and fungi because fields are already drying down.

September 4, 2020 — Western Iowa farmer Howard Vlieger just sent us the Sept. 3 photo below, showing northwest Iowa cornfields tired and fired; soon ready for the combine.

We’ve encouraged corn growers to plan their residue-breakdown application as an independent operation. Line up a helper literally chasing the combine with a tractor, shredder and on-board spraying rig. Our favorite type of stalk muncher is the flail chopper and piggyback sprayer like the one owned by Dave Schwartz of Guthrie County, Iowa (photo below). Dave has a standing agreement with a helper hired for the job every fall. It’s a simple job, and having a hired driver frees you totally to manage harvest. 

We’ve seen several growers delay the residue-decomposing trip until the combine is back in the shed in late October or November. Then, nights are below freezing. Beneficial bacteria and fungi go dormant and cold temps threaten sprayer freeze-ups. That often forces the farmer to postpone the residue breakdown treatment until early spring, or skip it totally.

Dave has found that after a few years of no-till, cover crops and early fall residue digestion, the light mulch of stalks left behind the shredder are so fragile he could plant no-till without special row-cleaning attachments. A standard opening coulter clips through the crumbling residue without hairpinning or distorting consistent planting depth.

He’s a dedicated advocate of clean water, and sees the combination of covers, no-till and residue digestion vital. His test-farm results reveal the yield gains of gradual biological buildup: “This year, I’m estimating that my few acres of bottomland corn will have some 200-bu. test plots — even though we had only four inches of rain all season.”


Six-row stalk shredder plus residue-digester
sprayer used by Dave Schwartz

His farm was in the pathway of the Aug. 10 derecho winds that flattened a huge swath of crops across central and eastern Iowa. The steeply rolling topography of his farm may have offered some shelter from the 100-mph wind, but nearby farms in the same terrain had extensive downed corn. “Neighbors were asking what corn numbers I planted,” Dave told us. “They had planted some of the same hybrids I did, but theirs went down.”

We attributed that standing-strength benefit to deep rooting and good soil health, built up over several years. 

When Dave harvests corn this fall, his helper will follow the combine with the chopper/spray rig shown in the nearby photo. He will apply Biodyne USA’s Meltdown mix of microbes, plus some 28% nitrogen to accelerate the organisms by narrowing the nitrogen/carbon ratio.

We browsed online auction sites and saw a wide array of used chopper-shredders for $4,000 to $9,000. Most farmers have an older utility tractor that could be available for the job. Here at Renewable Farming, we have a well-experienced Brady flail shoppe which covers six 30-inch rows. When shredding stalks, we’ve usually lowered it to just skim the ground. That tears up root crowns and kicks up a little soil, so “down and dirty” residue gets mingled with soil organisms. A simple 12-volt pump can power the sprayer on board the shredder. Spraying behind the shredder, right into the flying stalks and leaves, assures good coverage.


Drought-decimated corn in northwest Iowa, September 3, 2020