Mastering soil health elevates farm productivity, sustainability (PART 2)

by Dennis Pollock– Western Farm Press

Four soil health approaches

Mitchell said much has been learned from a research plot at the UC center where four approaches take place, including standard tillage and no cover crop, standard tillage and cover crops, no tillage and no cover crop, and no tillage and cover crops.

“Behind me is a very important field,” he said, referring to a research plot home to a growing number of crops in recent years, including cotton, processing tomatoes, corn, wheat, garbanzo beans, and sorghum.

Mitchell closed the meeting with the observation he believes it’s possible to grow still more crops using the no-till/cover crop approach which has gained more favor in the wake of years of drought. For one thing, he said the system of adding residue keeps the ground cooler which keeps soil organisms alive and saves water use.

Sloane Rice, a hydrology student at UC Davis, echoed the notion that cover crops are a key to improving water management by increasing water retention.

Other savings from no-till have long been known, including reduced labor costs, wear and tear on tractors, and savings on diesel fuel due to fewer passes across field. In addition, dust is reduced by nearly 70 percent.

Armchair scientist

Retired organic grower Tom Willey conceded there have been some challenges to those who grow organically. Willey said he struggled for 30 years to get more attention from scientists and researchers on organic production.

“I had to become an armchair scientist,” Willey noted.

He added that organic farmers “till and cultivate more intensively than their conventional brethren.”

“Until organic systems somehow learn to embrace no-till, a unique challenge in vegetable production, we’ll need to shovel lots of ‘coal’ into the firebox, possibly outstripping compost feedstock resources should acreage greatly expand,” Willey said.

He said soil-applied compost functions “like an interest-bearing savings account.” Nitrogen slowly mineralizes through secondary microbial degradation of organic matter, and nutrients are released from “predator-prey” soil interactions.

Willey said a better understanding of soil biology “is poised to take almost all of the chemicals out of agriculture. It will bring good farming and we won’t have to call it conventional or organic – just good farming.”

The new emphasis on good farming has truly moved into the soil, not just looking at yields and production of what is growing above it. It means looking at the complex interaction of microbial organisms underground and takes into carbon added to the soil.

Healthy soil = genetic diversity

Howard Ferris, UC, Davis nematologist, looked at the suppression of pest species underground, pointing out that some nematodes are beneficial in keeping problem nematode pests at bay.

He said healthy soil sustains plant and animal productivity, and provides a reservoir for genetic diversity. Organisms in the soil decompose organic materials, sequester and redistribute minerals, mineralize organic compounds, and regulate and suppress pests.

They improve soil structure and reduce soil erosion.

“With healthy soil, you can smell it,” Ferris said. “It’s healthy and alive.”

With the diversity of species in the soil comes higher levels of carbon, he said.

Radomir Schmidt, UC Davis soil microbiologist, referred to soil as part of “a solar-powered engine.” He is researching DNA sequencing of microbes, a complex process that could help in better understanding interactions of various microbes.