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Archive | Eco-Philosophy

Diverse Plant Communities Resist Invasive Species

diverse-oak resist invasive.tifHerbivores consume more nonnative oak leaf material in areas with diverse native plant communities than in less diverse communities. Why diverse plant communities tend to resist invasion by non-native or invasive species remains uncertain. Researchers from the Illinois Natural History Survey and the Morton Arboretum have been examining the potential role of herbivores on the invasion of nonnative plant species in diverse plant communities. The researchers examined herbivore damage on leaves of non-native oak trees in arboreta across the United States. They found that non-native oaks in regions with high oak species diversity showed more leaf damage than those in regions with low diversity.

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

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.

Plant Communities Beat Monocultures

Plant communities.tifAlthough monocultures can be cultivated efficiently, they are anything but sustainable: environmental damage to soil and water caused by monoculture cultivation is becoming increasingly evident, even beyond in-the-know sustainable farming circles. Despite their disadvantages, however, monocultures remain the principal crop form and are often regarded as the sole possibility for achieving higher yields in plant production — quite wrongfully, finds Bernhard

Schmid, an ecology professor at the University of Zurich. Schmid sees “an opportunity for the future of nutrition for humankind in the untapped potential of biodiversity” — a promising prospect as the OECD and the United Nations’ Food and Agriculture Organization (FAO) are giving off worrying signals: Both organizations predict that agricultural productivity will rise less steeply in the future than has been the case thus far.

In a 10-year study, a team of researchers from Switzerland, Germany and the Netherlands examined the yields from grassland plants which they had cultivated in monocultures or mixed plant communities. The latter proved to be more productive than the monocultures. Continue Reading →

Diversified Farming Better for Wildlife

diversified habitat.tifA study by scientists at Stanford and the University of California, Berkeley, published in Science, shows that evolutionarily distinct species suffer most heavily in intensively farmed areas. They also found, however, that an extraordinary amount of evolutionary history is sustained in diversified farming systems, which outlines a strategy for balancing agricultural activity and conservation efforts. The findings arise from a 12-year research project conducted by Stanford scientists at the intersections of farms and jungles in Costa Rica. Much of the research has focused on how farming practices can impact biodiversity, and has gone so far as to establish the economic value of pest-eating birds and crop-pollinating bees. Not surprisingly, the diversified farmlands supported on average 300 million years of evolutionary history fewer than forests. But they retained an astonishing 600 million more years of evolutionary history than the single crop farms.

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

Understanding Grain Defense Mechanisms

grain fields.tifCrop scientists at Washington State University have explained how genes in the barley plant turn on defenses against aging and stressors like drought, heat and disease.

Professor Diter von Wettstein and assistant research professor Sachin Rustgi showed that specific genes act as a switch that enables barley to live longer and become more tolerant of stress, including attack by common diseases like mildew and spot blotch.

The findings, reported in the Proceedings of the National Academy of Science, solve a long-standing mystery and offer hope for production of grain crops able to thrive during unpredictable weather and climate change. Cereal grains such as wheat, barley, corn and rice need an essential amount of growing time to produce abundant yields. Environmental stressors such as heat and drought can trigger early aging of plants, which slows growth and decreases yield and grain quality.

Von Wettstein and Rustgi discovered that two barley genes, called JIP60 and JIP60-like, play a major role in the protective actions triggered by a key plant defense hormone called jasmonate or JA. Like a watchful sentry, JA responds at the first sign of plant distress, producing proteins that prepare the plant to combat excess heat, lack of water or attack by disease organisms. The proteins also slow aging. It had been known since the 1990s that JA played a role in plant resistance but von Wettstein and Rustgi are the first to document how resistance actually takes place.

This summary appears in the November 2014 issue of Acres U.S.A.

True Grit in Battle Against Weeds

battle-against-weedsU.S. Department of Agriculture agronomist Frank Forcella has devised a tractor-mounted system that uses compressed air to shred small annual weeds like common lambsquarters with high-speed particles of grit made from dried corn cobs. Ongoing field trials may confirm the system’s potential to help organic growers tackle infestations of weeds that have sprouted around the bases of corn, soybean and other row crops.

Dubbed “Propelled Abrasive Grit Management” (PAGMan), the weed control system Forcella is testing disperses 0.5-millimeter-sized grit particles in a cone-shaped pattern at the rate of about 300 pounds per acre using 100 pounds per square inch of compressed air.

This summer marked a second round of field trials of PAGMan on multiple rows of silage corn grown on 10-acre plots of certified organic land in Minnesota. Field trial results from 2013 showed season-long weed control levels of 80 to 90 percent in corn using two treatments of the abrasive grit-one at the first leaf stage, and the second at the three- or five-leaf stage of corn growth. Corn yields also compared favorably to those in hand-weeded plots used for comparison.

The crop plants escape harm because they are taller than the weeds during treatment and their apical stems (growing points) are protected beneath the soil by thick plant parts. Results from small-plot studies have been published in Weed Technology and other journals.

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