cover crops

Greenhouses and the environment

July 25, 2024 By EarthWise Leave a Comment

The use of greenhouses around the world has been growing dramatically. A new satellite mapping exercise estimated the total land area covered with permanent greenhouses at 3.2 million acres, which is an area the size of Connecticut. More than half of this is in China, where the growth of greenhouses has been driven by the rapid urbanization of the country and by a more prosperous population increasingly consuming produce like tomatoes, cucumbers, peppers, and eggplants.

The intensive agricultural methods employed within greenhouses can be harmful to local environments because of overtaxing water supplies and by polluting rivers and soils with nutrients, pesticides, and plastic waste. But the effects of vast areas of plastic coverings on local temperatures can be even more dramatic, and often beneficial.

There are so many plastic and glass roofs in many areas that they are reflecting sufficient amounts of solar radiation to cool local temperatures. Greenhouse roofs increase the albedo – the reflectivity – of the land surface typically by a tenth.

All these greenhouses are just the tip of the albedo iceberg. Many farms now temporarily cover crops with reflective plastic sheets. If these coverings are included in the satellite survey, the total reflective area would be about ten times greater – roughly the size of New York State.

A study in Almeria, on the Mediterranean coast of Spain, which grows about 3 million tons of fruit and vegetables annually, determined the cooling effects of greenhouses. Weather stations amid the greenhouses showed an average cooling of 1.3 degrees Fahrenheit compared with the surrounding area.

Greenhouses are an accidental and benign form of climate engineering. The cooling provided by greenhouses is similar to the effect of white roofs in urban areas.

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Could the Global Boom in Greenhouses Help Cool the Planet?

Photo, posted September 6, 2017, courtesy of Lance Cheung / USDA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Managing Pests With Cover Crops | Earth Wise

May 18, 2022 By EarthWise Leave a Comment

The use of pesticides in global agriculture brings with it many problems including the killing of non-target, beneficial species as well as reversing pest-management gains from the use of conservation agriculture methods.

In a newly published study by researchers at Penn State University, the use of plant cover, such as cover crops, was shown to potentially be more effective at reducing pest density and crop damage than the application of insecticides without the downsides. Cover crops reduce insect pest outbreaks by increasing pest predator abundance.

Cover crops are plantings that are primarily used to slow erosion, improve soil health, enhance water availability, smother weeds, and help control pests and diseases. Typical cover crops include mustard, alfalfa, rye, clovers, buckwheat, and winter peas. Most cover crops are fairly inexpensive to plant.

Plant cover can provide habitat for populations of natural enemies of pests. Winter cover crops can harbor pest predator populations outside of the growing season of the cash crop. When the cover crop is killed off to allow the growth of the cash crop, residues of the cover crop remain on the soil during the growing season, so they still enhance the habitat for pest predators.

Conservation agriculture includes methods like cover crops, no-till planting, and crop rotation. The use of cover crops constitutes a form of preventive pest management that is an alternative to planting seeds treated with systemic insecticides to control early-season pests. There is also the possibility for integrated pest managements, which is an approach in which insecticides are applied but only when pest numbers exceed economic thresholds despite the use of nonchemical tactics.

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Cover crops more effective than insecticides for managing pests, study suggests

Photo, posted August 8, 2011, courtesy of USDA NRCS Montana via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Healthy Soil Is Healthy For People | Earth Wise

March 30, 2022 By EarthWise Leave a Comment

A new study by researchers at the University of Washington looked at the impact of regenerative farming practices on the nutritional content of the food that is grown.

Regenerative agriculture involves farming practices that not only “do not harm” to the land but actually improve it by regenerating and revitalizing the soil. The practices focus on topsoil regeneration, increasing biodiversity, improving the water cycle, and enhancing ecosystem services. Examples are soil-building techniques that minimize plowing, the use of cover crops, and the planting of diverse crops rather than monocultures.

The study included 10 farms across the U.S. that followed soil-friendly practices for at least five years. The results were that the crops from those farms had a healthier nutritional profile than the same crops grown on neighboring, conventional farms. In particular, there was a boost in certain minerals, vitamins and phytochemicals that are beneficial to human health. Across the board, regenerative practices resulted in crops with more anti-inflammatory compounds and antioxidants.

The participating farms grew one acre of a test crop – peas, sorghum, corn, or soybeans – for comparison with the same crop grown on a neighboring farm using conventional agriculture. Analysis showed that the farms practicing regenerative agriculture had healthier soils, as measured by their organic matter – or carbon – content and by other tests.

Organic farms avoid chemical pesticides, but they operate with a variety of farming processes. Nonetheless, they have also been found to produce crops with higher levels of beneficial nutrients. The biology of the soil in which crops are grown is an important factor for human health. It isn’t just what we eat that matters; it is how we grow it.

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Farms following soil-friendly practices grow healthier food, study suggests

Photo, posted January 10, 2020, courtesy of Les via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.