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Archive | Soil Life

Soil Ecosystems: Maintaining Critical Microbial Life

earthworm soil life.tifSoil ecosystems aren’t always the first things people notice when they are in nature.

When asked to describe a forest or a meadow, most people would probably begin with the plants, the species diversity or the color of the foliage. They probably wouldn’t pay much attention to the soil ecosystems and the critical microbial life. But a new Yale-led study shows the importance of earthworms, beetles and other tiny creatures to the structure of grasslands and the valuable soil ecosystem services they provide.

During a 3-year study, researchers found that removing these small animals from the soil of a replicated Scottish sheep meadow altered the plant species that grew in the ecosystem, reduced overall productivity and produced plants that were less responsive to common agricultural management, such as fertilization.

The results reflect the long-term ecological impacts of land use changes, such as the conversion of forests to agricultural land, researchers say.

“We know these soil animals are important controls on processes which cause nutrients and carbon to cycle in ecosystems, but there was little evidence that human-induced loss of these animals has effects at the level of the whole ecosystem on services such as agricultural yield,” said Mark Bradford, lead author of the study published in the Proceedings of the National Academy of Sciences.

This article appears in the December 2014 issue of Acres U.S.A.

Soil Ecosystems: Nutrient Additions

New research from Iowa State University shows that agricultural inputs such as nitrogen and phosphorus alter soil microbial communities and soil ecosystems. Adding nitrogen and phosphorus fertilizers, commonly used as fertilizers, to the soil shifts the natural communities of fungi, bacteria and microscopic organisms called archaea that live in the soil, said Kirsten Hofmockel, associate professor.

Hofmockel and other scientists associated with the Nutrient Network, a global group of scientists, revealed that microbial community responses to fertilizer inputs were globally consistent and reflected plan responses to the inputs. Many soil microbes perform helpful functions in the native ecosystems and altering those microbial communities may have negative environmental consequences, Hofmockel said. The researchers found nutrient additions favored fast-growing bacteria and decreased the abundance of fungi that share a symbiotic relationships with grassland plants.

This encapsulation of the research is from the December 2015 issue of Acres U.S.A.

Soil Ecosystems: Synthetic Nitrogen Lingers for Decades

Nitrogen fertilizer applied to crops lingers in the soil ecosystems and leaks out as nitrate for decades towards groundwater — “much longer than previously thought,” scientists in France and at the University of Calgary say in a new study.

Thirty years after synthetic nitrogen (N) fertilizer had been applied to crops in 1982, about 15 percent of the fertilizer N still remained in soil organic matter, the scientists found.

After three decades, approximately 10 percent of the fertilizer N had seeped through the soil ecosystem toward the groundwater and will continue to leak in low amounts for at least another 50 years.

The findings show that losses of fertilizer N toward the groundwater occur at low rates but over many decades, says Bernhard Mayer, U of C professor of geochemistry and head of the Applied Geochemistry Group.

That means it could take longer than previously thought to reduce nitrate contamination in groundwater, including in aquifers that supply drinking water in North America and elsewhere, he says.

“There’s a lot of fertilizer nitrogen that has accumulated in agricultural soils over the last few decades which will continue to leak as nitrate towards groundwater,” Mayer says.

Canada and the United States regulate the amount of nitrate allowed in drinking water. In the 1980s, surveys by the U.S. Environmental Protection Agency and the U.S. Geological Survey showed that nitrate contamination had probably impacted more public and domestic water supply wells in the United States than any other contaminant.

The study, “Long-term fate of nitrate fertilizer in agricultural soils,” was published in the Proceedings of the National Academy of Sciences.

This summary appears in the December 2013 issue of Acres U.S.A.

Interview: Poisoning Paradise for Profit — International Organic Authority, Author & Farmer André Leu Shatters the Myths of Safe Pesticides

André Leu Interview

André Leu

André Leu interviewed by: Chris Walters


Over the years a queasy complacency has replaced the alarm once triggered by the subject of pesticides. While millions of people strive to avoid using them or eating food containing residues, many millions more accept their continued use in the belief that agricultural chemicals are understood, regulated and used with discretion. André Leu’s new book, The Myths of Safe Pesticides, demolishes these notions with a steady stream of hard facts derived from solid science. He puts a hand grenade into the layer cake of wishful thinking, and there isn’t much left after it goes off. As he explains, Leu was moved to write the book by repeated exposure to a series of mistaken ideas about pesticides, massaged into the public mind by public relations professionals working for industrial ag concerns. He hears these dangerous misapprehensions parroted far and wide as he travels the world in his capacity as president of IFOAM, the international organic umbrella group. Hailing from Queensland, Australia, Leu raises tropical fruit in a bucolic spot where the tropical rainforest meets the Great Barrier Reef. His activism on behalf of sustainable farming brought him increasing prominence over several decades, leading to his current post. He is a longtime friend of Acres U.S.A.

ACRES U.S.A. Every so often an apologist for mainstream agriculture takes the line that Rachel Carson and her supporters overstated the problem, since their apocalyptic fears of pesticide effects were not borne out in the decades following publication of Silent Spring. DDT was banned, better chemistry came on the market, integrated pest management techniques evolved, and so on. The world didn’t end. What do the facts really tell us?

ANDRÉ LEU. The reality is that after generations of increasing life expectancy, we’re at the point now in the developed world where we are looking at the first generation that will have a shorter life expectancy than ourselves, so we can see that something clearly isn’t right. If you look at the U.S. President’s Cancer Panel report, it clearly says that 80 percent of cancers are caused by what we call outside environmental influences, of which chemicals are one of the most considerable causes. That is also backed up by the International Agency for Research on Cancer which says breast cancer, for instance, is at an epidemic level when we measure the number of women getting it and the number of women dying. In the developed world we have much better medical intervention, so we’re getting higher survival rates. In the rest of the world, where they don’t have our level of medical care, there’s incredible mortality. The United Nations’ World Health Organization maintains an environmental program looking at endocrine disrupters, particularly diseases of the sexual tissues. Those cancers are on the rise — birth defects, lower reproductive rates. Across the board we can see negative health outcomes as a result of chemicals. This is borne out by good, peer-reviewed science. It’s not dogma, it’s published, peer-reviewed science, meta-studies by the WHO and findings of the President’s Cancer Panel in the United States. We’re talking about some of the world’s best experts getting together, reviewing all the data and presenting their findings. They cannot be discredited and ignored. Continue Reading →

More Accurate Soil Testing

soil testingSoil testing that determines needed fertilizer will measure nitrate in the soil, but tests don’t sufficiently account for soil microbes, which mineralize organic nitrogen and make more of it available to a crop. As a result, farmers often apply more fertilizer than necessary.

Richard Haney, a U.S. Department of Agriculture soil scientist in Temple, Texas, has developed soil test that replicates some of the natural processes that occur in a field and accounts for microbial activity, along with measuring nitrate, ammonium (NH4) and organic nitrogen.

The new soil test is known as the Soil Health Tool. It involves drying and rewetting soil to mimic the effects of precipitation. It also uses the same organic acids that plant roots use to acquire nutrients from the soil. The testing tool measures organic carbon and other nutrients, accounts for the effects of using cover crops and no-till practices and works for any crop produced with nitrogen or other types of nutrient fertilizer. For more information visit http://www.ars.usda.gov/is/pr/2014/140710.htm

This article appears in the September 2014 issue of Acres U.S.A.

Companion Planting

Companion planting

by Jeff Poppen

Recent discoveries in quantum physics, microbiology and ecology verify something gardeners have long known. Everything in nature is related. There are no solid lines between the plants’ roots, the soil and the bacteria and fungi tying it all together. To help understand why garden crops do or do not thrive, we are led into the enigmatic field of companion planting.

Just as we work and feel best around our friends, plants will grow better in their preferred company. Although the reasons may be obscure, a lot of observation and a little intuition can reveal mutual attractions and aversions. The garden teaches us the value of old-time practices, fresh experiments and keeping our eyes open. Continue Reading →

Crop Rotation: 7 Steps to Enhance Your Soil Life

rotation and nematode d2350-1

Crop rotation leads to increased soil life.

Crop rotation has been used since Roman times to improve plant nutrition and to control the spread of disease. A study published in Nature’s The ISME Journal reveals the profound effect crop rotation has on enriching soil with bacteria, fungi and protozoa.

Crop rotation simply means changing the type of crop grown on a particular piece of land from year to year which includes cyclical and non-cyclical rotations. Good crop rotation includes planning ahead two or more years. A lack of planning can lead to problems including the buildup of soil-borne diseases or imbalances in soil nutrients and an increase in pests.

“Changing the crop species massively changes the content of microbes in the soil, which in turn helps the plant to acquire nutrients, regulate growth and protect itself against pests and diseases, boosting yield,” said Professor Philip Poole from the John Innes Centre.

Soil was collected from a field near Norwich and planted with wheat, oats and peas. After growing wheat, it remained largely unchanged and the microbes in it were mostly bacteria. Crop rotation by growing oat and pea in the same sample caused a huge shift toward protozoa and nematode worms.

Seven Crop Rotation Steps

A good crop rotation plan should include the following steps:

Step 1. Identify and prioritize your goals. Your goals may to be build better, healthier soils, control pests, minimize soil-borne diseases, reduce weed pressure and to produce the most nutritious foods possible.

Step 2. Write down the mix of fruits, vegetables and cover crops that you plan to grow next season along with each crop’s planting and harvesting dates.

Step 3. Write the plant’s family name next to each crop and then add up the amount of garden space in square feet that will be allocated for each family. If one family will be grown on more than 25 percent of your garden, then consider increasing the diversity of your crop mix. Having a high proportion of your garden in one family might mean that a location will rotate back to that family too soon, which can lead to soil-borne diseases.

Step 4. Make a crop rotation planning map. Think about how you will divide your garden into small units of somewhat equal sizes. These units could be long rows or individual beds of any shape. Making this map and having your garden divided into these units allows you to keep track of what you planted on a piece of ground years later. The map of your garden will show every unit. The map should be large enough so that information can be written inside each unit. For this mapmaking, 12 x 16 sketch paper or a computer works well. Sample maps can be downloaded. When you are done making your map and before you start filling in each unit’s information, make at least six to eight copies. Next, assign a color for each plant family, cover crop, mulch and fallow periods.

Step 5. On another copy of your map, designate each crop to as many units as you need to meet the area of your specific crop mix. If a unit will be double or triple cropped, separate their names with dashes such as May lettuce-buckwheat cover-fall spinach. If you plan on growing two or more of the same crop family on a unit, use slashes to indicate this (tomato/peppers/potato). When placing a crop onto a unit, try to pair crop families together on a given unit, but avoid placing a family onto a unit that has had that same family on the unit in the previous few years. At this time you may match the colors you’ve chosen for families and color them onto the appropriate units.

Step 6. Once you have your maps finished with the crops written inside each unit, numbered and colored, along with any other usable information, then take your maps and walk your garden. Imagine how it will look and consider the tillage, planting, care and harvesting of your crops and if the proposed crop sequence makes sense for a given location. At this time also take into consideration equipment, irrigation and labor needs.

Step 7. Develop a backup plan by thinking ahead to any problems that may arise with growing a crop within a unit, such as if a spring may be too wet for early planted crops or certain transplants are unavailable at a critical time or who will take over your labor duties if something happens to you and you have to be away for an extended period of time. Write down your backup plans for coping with various problems and make provisions for these possible problems.

Every garden is unique and each gardener will have their own specific needs, but there are principals and general rules of thumb that should be followed when thinking about a new rotation.

  • Follow legume cover crops such as clover with high-N demanding crops.
  • Grow winter-killed cover crops before early-season crops.
  • Never grow any crop after itself.
  • Use crop sequences that promote healthier crops such as cabbage family crops following onions or potatoes following corn.
  • Avoid growing one heavy feeder after another heavy feeder.
  • Grow tomatoes after peas, lettuce or spinach, because tomatoes take a lot out of the soil.
  • Grow beans after sweet corn to rebuild nitrogen levels.
  • Use a cover crop’s residue to help build organic matter levels.
  • When growing a wide mix of crops, try grouping into units according to plant family, timing of crops planting dates and harvesting dates.
  • A minimum return time of a crop should be in the four-to-five year range, which often prevents most soil-borne diseases.
  • Attempt to keep something growing throughout the year, which keeps the ground covered, protecting the soil and at the same time will supply organic material for earthworms and beneficial organisms living within the soils. Incorporating cover crops into a rotation makes this possible.

Rotations are an important part of any gardening system. Yields of crops grown in rotations are typically 10 percent higher than those of crops grown in monoculture in normal growing seasons and as much as 25 percent higher in droughty growing seasons.

Adding cover crops to a rotation can add organic matter, enhance mycorrhizal numbers, add nitrogen, suppress weeds and nematodes, reduce soil erosion, increases infiltration of water, decreases nutrient loss and attracts beneficial insects.

Planning Crop Rotation in Vegetable Gardens

There is a growing consciousness around growing one’s own food and the reasons for doing so vary from person to person. Tough economic times, high unemployment, rising food costs and a desire to provide one’s family with fresh, super nutritious food are just a few examples.

One fact that remains the same is that gardener’s put a great amount of care, hard work and time into their gardens only to sometimes achieve mediocre results.

The one factor that we have no control over is Mother Nature. Gardening is inherently risky and pests, drought, flooding and wind along with other weather extremes can all destroy a year’s work. A good example of an extreme weather event would be the severe drought of 2012 that stretched across more than half of the United States and the record number of 90-plus days. With many of those days reaching up into the triple digits. The result was scorched crop fields, pastures and gardens. The drought was so extensive that it also created problems concerning producers’ water supplies. Creeks, rivers, ponds, lakes and aquifers had dangerously low water levels, while others completely dried up.

The number of farmers, livestock producers and gardeners who experienced crop and animal losses in 2012 will not only be felt by them, but will be felt by most American consumers. A large portion of our economy depends on agriculture.

Irrigation was a lifesaver in 2012 for those who had systems in place, but even then some farmers and gardeners were still unable to keep up with demand and eventually had to give up in the face of low water supplies and high fuel bills.

Many gardeners who utilized drip irrigation with mulch or a plastic layer had good results and were able to produce an abundant crop within their gardens.

There are many tools and techniques that growers use to grow their food, somethings they have control over, and others not, but one technique often misunderstood and under valued is crop rotations within a garden.

The smaller a garden is and when a gardener is only growing two or three different crops, it then becomes more difficult for a crop rotation to be effective. There are ways in which a gardener can increase his success rates and be extremely efficient and they include using mulch, compost, manure and short-term cover crops.

Name Game

In the world of gardening there are so many names that it can be confusing and intimidating, but a new gardener who does not understand those horticulture names could make the wrong choice of plants for their garden and the crop rotation plan. To become more knowledgeable with these horticulture names stop by your local library and check out a few books on vegetable gardening, use the Internet, ask your local garden center staff or an experienced gardener. Understanding the vocabulary that comes along with gardening and a crop rotation can make the planning easier and gardening in general a lot more enjoyable, productive and successful.

— by Chad King

Earthworms Escape Drought Underground

EarthwormsEarthworms use water for many things — for respiration, to keep their bodies from drying out and to make the mucus that helps them slide through the soil. When soils get dry, earthworms go into estivation. “During estivation, earthworms wrap their bodies into a tight knot to reduce the amount of surface area exposed to the soil,” explains Jacob McDaniel, lead author of a study published in Soil Science Society of America Journal. “Then they’ll seal themselves up in a chamber lined with their mucus. Inside that chamber, the humidity is higher so they don’t dry out as the soil dries.”

This article appears in the November 2013 issue of Acres U.S.A.