Cover crops do so much more than just cover soil. They have a variety of advantages, including the potential to prevent soil erosion and improve soil health. They can entice pollinators, fight pests, decompose into ‘green manure,’ or be fed to livestock.
According to a new study, the advantages of cover crops extended even into semi-arid regions. This evaluation was published recently in the Soil Science Society of America Journal, a Soil Science Society of America journal.
“A lot of the study data we have on cover crops comes from high-precipitation areas,” explains Humberto Blanco, chief researcher at the University of Nebraska – Lincoln. “As a result, uncertainties concerning the ecological services offered by cover crops in dry regions remain.”
Some critics have suggested that cultivating cover crops in drier locations may consume too much water. As a result, later food crop production may decrease. However, the research reveals that this is not always the case.
“We discovered that cover crops can increase most ecosystem functions in water-stressed situations,” Blanco adds. “In the vast majority of cases, these enhancements have no negative impact on food crop output.”
To investigate how good cover crops perform in semi-arid environments, Blanco and colleagues gathered and analysed a few research papers on cover crops in arid climates. They prioritised research on the semi-arid Great Plains of the US.
The researchers investigated cover crops in relation to many ecosystem services. These included, among other things, the amount of organic carbon in soils, soil microbial characteristics, weed management, and food crop yields. Soil organic carbon was one of the primary soil properties studied by the researchers.
“Soil organic carbon acts as a catalyst for many other changes in soil characteristics and soil functions,” Blanco explains. “Soils in water-stressed areas are frequently poor in organic carbon.”
The researchers discovered that in dry locations, cover crops boosted soil organic carbon levels over 60% of the time.
“This organic carbon storage is crucial to these soils,” Blanco explains. This is because soil organic carbon serves as a food supply for many soil organisms such as bacteria. Finally, soil microbes play an important part in keeping healthy, rich soils.
Weeds are also suppressed by cover crops in dry places. This is critical since numerous weed species are resistant to current herbicides. Weed reduction by cover crops has a knock-on effect on water conservation and soil erosion prevention.
“Herbicide-resistant weeds can cause ploughing in normally no-till settings,” Blanco explains. “This may adversely affect the ability of certain agroecosystems to conserve water.” Tilling can also make soils vulnerable to erosion.
In dry locations, cover crops also provide feed for livestock. “Grazing or mowing grass cover crops can boost net returns without eliminating soil advantages,” Blanco explains. This is because even when grazed, a considerable part of cover crops remain on fields. Cover crop roots also survive even when grazed, helping to keep soils together and offering other advantages.
Cover crops, according to the study, can diminish food crop yields in some circumstances. These occurrences were often associated with occasional extreme drought. During these years, the availability of water for cover and food crops reduced.
“It’s vital to adapt crop rotations and cover crop use to weather conditions,” Blanco explains. “In drier places, farmers may not be able to sow a cover crop every year.” They can target wet years when cover crops are likely to succeed.”
Blanco intends to continue studying cover crops in arid locations.
“Long-term study is essential to determining the long-term consequences of cover crops,” he says. “However, long-term research data on cover crops in arid and semi-arid areas are almost non-existent in the research.”