Tag: soil

Posted on

Soil Cannot Mitigate Climate Change

Field
Crop Field: Using crops to transfer carbon dioxide into the soil has been found to be an unrealistic option.

It was once a groundbreaking idea that that climate change mitigation was plausible by burying carbon in the ground. However, in late February of 2018 scientists at Rothamsted Research published their findings in the journal Global Change Biology that soil data stretching back to the mid 19th century demonstrates that carbon emissions cannot be stored in the ground. The researchers concluded this by analyzing of the rate of change in carbon levels in soil.

The original idea of using crops to collect carbon from the atmosphere and burying it in the soil was proposed in 2015 at an international conference. The aim of this proposal was to increase carbon sequestration (the removal of carbon dioxide from the atmosphere and holding it solid or liquid form) by “4 parts per 1000.” The researchers at Rothamsted insisted that this rate was unrealistic for such large areas all over the planet, stating that levels of soil carbon are not unrestricted; as the levels increase, they move towards equilibrium and eventually stop growing.

Data from 16 experiments on three different soil types were examined, giving 110 treatment comparisons. The researchers observed the “4 per 1000” rate of growth in soil carbon levels in some cases, but only when such extreme measures were taken that they would be impractical in a real-life setting.

Not only did these experiments prove the impracticality of the “4 per 1000” initiative, but also displayed that high rates of soil carbon increase can be achieved by removing land from agriculture. However, this extreme decrease in agriculture over vast expanses of land would be incredibly damaging to global food security. To mitigate this problem, researchers have suggested returning residue from crops to soil as an effective solution to increase carbon soil sequestration; this has been observed as an practical method used by some countries in smallholder agriculture settings.

The researchers also suggested that long-term crop rotation with occasional introduction of pasture could lead to significant soil carbon increases. While the environmental benefits are clear, this method is economically impractical for most farmers. In order for an effective change in agricultural methods to be plausible, there would have to be implementation of new policy or guidelines.

Overall, the “4 per 1000” initiative is unrealistic as a major contribution to climate change mitigation. The scientists at Rothamsted Research suggest that there has to be more logical reasoning for promoting practices that increase soil carbon levels is more important to ensure sustainable food security and wider ecosystem services.

Paul Poulton, Johnny Johnston, Andy Macdonald, Rodger White, David Powlson. Major limitations to achieving “4 per 1000” increases in soil organic carbon stock in temperate regions: Evidence from long-term experiments at Rothamsted Research, United Kingdom. Global Change Biology, 2018; DOI: 10.1111/gcb.14066

Posted on

How to Feed 7.6 billion People

Can our current farming systems keep up with a growing population, while also protecting the land we eat from? It’s a tough question, but a study published earlier this year suggest it is possible. The research focuses on farms in the Northern Plains of the United States, specifically those under a conventional corn production system versus those under a regenerative agriculture system. Farms included in the study that were using regenerative agriculture practices never tilled their fields, did not use insecticides, grazed their livestock on the cropland, and grew a mix of cover crop species. The conventional farms included in the study practiced tillage, used insecticides, and left the soil bare after harvest.

Researchers collected soil cores from each farm to determine the amount of organic matter within. This, along with the abundance of pest, yield, and profit were assessed. Yield in this case was the gross revenue. The study found that regenerative agriculture systems had 29% lower grain production, but had 78% higher profits- two times that of conventional agriculture. In addition, there were ten times the amount of pest on fields treated with insecticides, than those that were not. All of this is because regenerative agriculture allows for nature to do its job. Spraying insecticides on a field is not only harmful to the environment, but is ineffective. Insects can adapt to new chemicals and will persist even more when their natural predators are eliminated by insecticides. Biodiversity within cropland can reduce the amount of pest and their persistence. Regenerative agriculture raises organic matter in the soil which in return allows for increased soil infiltration, diverse soil life, less fertilization, and lower input costs. Also, systems that incorporate livestock and cropland can see higher profits from the livestock as they can feed on the cover crops, reducing fodder input and allowing more of the corn harvested to feed humans.  Conventional farming sees smaller profits because of the high seed, fertilizer, and insecticide investments.

Regenerative agriculture has become a sustainable alternative to traditional farming because it provides ecosystem services, while producing higher profits than the more input intensive conventional system. Like many recent studies, the outcomes favor the unconventional farming method and show increased profitability and farm health for those using regenerative agriculture. The abundance of new research in agriculture shows that we can feed the world if we simply change how we grow our food. There needs to be a shift in farming values that prioritize the land, resources, and the quality of food over high yield numbers.

Source: LaCanne, C.E., and Lundgren, J.G. 2018. Regenerative agriculture: merging farming and natural resource conservation profitably. PeerJ 6: e4428.

Photo source:  Flickr

Posted on

Saving Soil: Case studies from the Great Plains

soybean field

They say you don’t know what you have until it’s gone, and that may very well be the case of Great Plains farmers and ranchers who are experiencing significant losses of soil due to erosion. A recently published study uses numerous case studies from the Great Plains states to highlight the importance of soil health to ensure soil security. Soil security recognizes the role soil has in meeting today’s global challenges of food security, water security, and climate change. Soil health influences the goods and services we receive from the soil, so it is necessary that we understand how soil is being both compromised and sustained. By making growers and consumers aware of the externalities of degraded soil health, we can hope to better the agricultural system. 

Land used for cultivation has increased over the last several years in the area of interest, drastically changing the landscape. Clearing land for crop use by conventional means, entails the removal of grasslands and perennial crop cover such as grasses and trees. In doing so, the soil becomes loose as it is no longer held together by roots and the topsoil becomes exposed. This allows for erosion by wind or water to occur. Wind can carry the soil into the air, creating dust storms capable of blocking sunlight. Water that runs off of the land can create gullies and carry sediment to nearby streams, affecting water quality and life within the streams. A gully formed 25 m wide by 95 m long and almost 10 m deep at a ranch in Texas.

The ranch owner notes,

“We’re still fighting erosion up here on all our land, is a constant battle, and we’re consistently losing creek bank after storms due to the severity of runoff upland of us…most creeks here hadn’t moved 5 feet [≈1.5 m] in decades, but now they’re moving 50–60 ft per year [≈17 m].”

The need for sustainable agricultural practices and improved land use planning with incentives for farmers to adopt soil or water conservation practices, is necessary. Conservation agriculture practices include no tillage or reduced soil disturbance, diversifying crop rotations, maintaining high levels of crop residue between plantings (corn stalks and stems left on the field between growing seasons), incorporating cover crops into crop rotations and integrating livestock into the cropping system. Soil is essential for nutrient cycling, biodiversity, and water regulation- not to mention, providing our world with food. Traditional farming practices cannot feed the world in a way that is both good for humans and the environment.

 

 

 

Source:

Benjamin L. Turner, Jay Fuhrer, Melissa Wuellner, Hector M. Menendez, Barry H. Dunn, Roger Gates. 2018. Scientific case studies in land-use driven soil erosion in the central United States: Why soil potential and risk concepts should be included in the principles of soil health. International Soil and Water Conservation Research. DOI.