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Archive | Soils

Humus: What is it and How is it Formed?

Secrets of Fertile Soils

Humus forms as a result of the complicated interplay of inorganic conversions and the life processes of the microbes and tiny creatures living in the soil — the soil ecosystem. Earthworms play a particularly important role in this process. Humus formation is carried out in two steps. First, the organic substance and the soil minerals disintegrate. Next, totally new combinations of these break down products develop, which leads to the initial stages of humus. Humus formation is a biological process. Only 4-12 inches (10-30 centimeters) of humus-containing soil are available in the upper earth crust. This thin earth layer is all that exists to provide nutrition to all human life. The destiny of mankind depends on these 12 inches!

Cultivated soils with 2 percent humus content are today considered high-quality farmland. What makes up the remaining 98 percent? Depending on the soil type, soil organisms constitute about 8 percent, the remains of plants and animals about 5 percent, and air and water around 15 percent.

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Nitrogen Fertilizer’s Long-Lasting Legacy

Aerial of intersecting roads in rural IndianaDangerous nitrate levels in drinking water could persist for decades, increasing the risk for blue baby syndrome and other serious health concerns, according to a new study published by researchers at the University of Waterloo. Nitrogen fertilizer applied to farmers’ fields has been contaminating rivers and lakes and leaching into drinking water wells for more than 80 years. The study, published in the journal Environmental Research Letters, reveals that elevated nitrate concentrations in rivers and lakes will remain high for decades, even if farmers stop applying nitrogen fertilizers today. The researchers have discovered that nitrogen is building up in soils, creating a long-term source of nitrate pollution in ground and surface waters. “A large portion of the nitrogen applied as fertilizer has remained unaccounted for over the last decades,” said Nandita Basu, a professor in the Department of Earth and Environmental Sciences and Civil and Environmental Engineering. “The fact that nitrogen is being stored in the soil means it can still be a source of elevated nitrate levels long after fertilizers are no longer being applied.” Their paper presents the first direct evidence of a large-scale nitrogen legacy across the Mississippi River Basin. Professor Basu and her group analyzed long-term data from over 2,000 soil samples throughout the Mississippi River Basin to reveal a systematic accumulation of nitrogen in agricultural soils. In many areas this accumulation was not apparent in the upper plow layer, but instead was found 25-100 centimeters beneath the soil surface.

This article appears in the May 2016 issue of Acres U.S.A.

Interview: Researcher, Author Eric Toensmeier Explores Practical, Effective Carbon Farming Strategies

Real-World Solutions

While this Eric Toensmeier_rgb (2)interview was being prepared a story surfaced on public radio about a couple of enterprising Americans who are taking advantage of changing policy to open a factory in Cuba. Their product? Tractors! The whole idea, the story helpfully explained, was to introduce “21st century farming” to the beleaguered island. By making it easier to tear up the soil. Clearly there is some distance to go before an accurate idea of 21st century farming penetrates the mainstream. It will take people like Eric Toensmeier. His new book, The Carbon Farming Solution, carries enough heft, range and detail to clear away forests of confusion. If the notion of leaving carbon in the soil is going to take its place next to that of leaving oil in the ground, this one-volume encyclopedia on the subject is exactly the kind of deeply informed work that’s required. Reached at his home in western Massachusetts, Toensmeier was exhilarated over finishing a project years in the making, and more than happy to talk about it.

This interview appears in the May 2016 issue of Acres U.S.A.

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Biochar as Substrate for Hydroponic Tomatoes

tomatoes USDA photoAs the use of soilless, hydroponic growing methods becomes more prevalent among crop producers, researchers are looking for new materials that can help growers save money, produce healthy plants and contribute to sustainable practices. The authors of a study in HortScience say that biochar, a charcoal-like material produced by heating biomass in the absence of oxygen, can help “close the loop” when used as a substrate for soilless, hydroponic tomato production. “This method could provide growers with a cost-effective and environmentally responsible green-waste disposal method, and supplement substrate, fertilizer and energy requirements,” said the study’s corresponding author Jason Wargent.

This article appears in the February 2016 issue of Acres U.S.A.

Cover Crops in Grazing Systems

cover crop winter pea, clover, cereal ryeNoble Foundation researchers are studying how cover crops could be part of a year-round grazing system that provides economic and environmental benefits to farmers and ranchers. Noble Foundation research agronomist James Rogers, Ph.D., received a three-year conservation innovation grant from the U.S. Department of Agriculture Natural Resources Conservation Service to conduct the research. The grant will support Rogers in determining how much moisture is used and/or conserved by summer cover crops and how those crops impact production of grasses and legumes consumed by livestock (commonly called forages) during the winter months. Moisture is a key  component of crop and forage production. Sufficient moisture levels boost pasture quantity and provide benefits to soil, which ultimately helps farmers and ranchers. “We need to determine whether the cover crops take moisture away from or preserve moisture for winter pasture,” Rogers said. “Preserving moisture will allow for earlier fall production. However, if the cover crops use up the moisture, winter pasture production is limited.”

This article appears in the February 2016 issue of Acres U.S.A.

Healthy Soils for a Healthy Life — Increasing Soil Organic Matter through Organic Agriculture

Better infiltration, retention and delivery to plants helps avoid drought damage. Organic is on the left, conventional on the right. Photo courtesy of Rodale Institute

Better infiltration, retention and delivery to plants helps avoid drought damage. Organic is on the left, conventional on the right. Photo courtesy of Rodale Institute

by André Leu

This year has been declared the International Year of Soils by the 68th UN General Assembly with the theme “Healthy Soils for a Healthy Life.” I am particularly pleased with the theme because this is a message that we in the organic sector have been spreading for more than 70 years, and at first we were ridiculed. Now there is a huge body of science showing that what we observed in our farming systems is indeed correct.

“Organic farming” became the dominant name in English-speaking countries for farming systems that eschew toxic, synthetic pesticides and fertilizers through J.I. Rodale’s global magazine Organic Farming and Gardening, first published in the United States in the 1940s. Rodale promoted this term based on building soil health by the recycling of organic matter through composts, green manures, mulches and cover crops to increase the levels of soil organic matter (SOM) as one of the primary management techniques.

Numerous scientific studies show that SOM provides many benefits for building soil health such as improving the number and biodiversity of beneficial microorganisms that provide nutrients for plants, including fixing nitrogen, as well as controlling soilborne plant diseases. The decomposition of plant and animal residues into SOM can provide all the nutrients needed by plants and negate the need for synthetic chemical fertilizers, especially nitrogen fertilizers that are responsible for numerous environmental problems. Continue Reading →