Beetles: an alternative to herbicides?

British and French researchers have found that ground beetles can reduce the number of weed seeds surviving in the soil, thus contributing to weed management and reducing the need for herbicides. The findings provide further support for calls to conserve farmland biodiversity.

The study, funded by the Biotechnology and Biological Sciences Research Council (BBSRC) and the French Institut National de la Recherche Agronomique (INRA), found that grass weeds were reduced more than other weeds, which is important because many UK farms have severe grass weed problems. Some of the species which were targeted by ground beetles are increasingly resistant to herbicides and can have significant effects on crop yields owing to competition for resources.

As herbicides become increasingly restricted, alternative means of weed control have the potential for significant impact. The report suggests that with the right management, ground beetles could replace some herbicide applications and significantly reduce weed populations. It goes on to say that agri-environment schemes such as Environmental Stewardship can already help to create suitable habitats for such invertebrates.

Read the full report here.

Roundup damages soil?

A recent Reuters report claims that heavy use of the glyphosate-based herbicide Roundup can cause damaging changes to soils as well as compromising yields of GM crops which US farmers are cultivating. Repeated use of glyphosate damages plant root structure and research indicates that the chemical could also cause fungal root disease, according to the United States Department of Agriculture (USDA).

According to the Reuters report, Roundup is the world's best-selling herbicide and its use has increased as Monsanto, the world's biggest seed company, continues to roll out herbicide-tolerant "Roundup Ready" crops. Roundup Ready corn, soybeans and other crops are beloved by farmers because farmers can spray the herbicide directly onto their crops to kill surrounding weeds, and Roundup Ready corn and soybeans varieties make up the vast majority of those crops grown in the United States.

In addition, website Motherjones.com quotes Iowa-based agronomy consultant Dr Michael McNeill, who claims that "farmers' increased use of Roundup is actually harming their crops because it is killing micronutrients in the soil that they need, a development that has been documented in several scientific papers by the nation's leading experts in the field. For example, harmful fungi and parasites like fusarium, phytopthora and pythium are on the rise as a result of the poison, while beneficial fungi and other organisms that help plants reduce minerals to a usable state are on the decline. The overuse of glyphosate means that oxidizing agents are on the rise, creating oxides that plants can't use, leading to lower yields and higher susceptibility to disease."

Monsanto has said in the past that glyphosate binds tightly to most types of soil, is not harmful and does not harm the crops. The company has said that its research shows glyphosate is safe for humans and the environment.

Livestock key to less desertification

A report in Australian magazine Farm Weekly suggests that using livestock is the only management tool available to combat climate change-induced desertification.

The ‘unpopular and controversial’ idea arises from observations made by Allan Savory, president of the Africa Centre for Holistic Management, of southern Africa, where it was noticed that the African savannah could support extremely large herds of herbivores year after year without degradation.

In contrast to this, land that was destocked to accepted optimum conditions and allowed to return to wilderness was increasingly subject to desertification. Mr Savory argues that subjecting grassland to occasional heavy grazing, which mimicked ‘natural’ conditions, actually improved vegetation growth. 

Read the full report here.

Pesticides lost to the atmosphere exceed losses through runoff

American researchers have revealed that pesticide losses to the atmosphere, through volatilisation, increase when soil moisture levels are high. A long-term U.S. Department of Agriculture (USDA) study found that herbicide volatilisation regularly exceeded herbicide losses arising through field runoff.

Scientists from the USDA Agricultural Research Service studied the field dynamics of atrazine and metolachlor, two herbicides commonly used in maize production. Both herbicides are known to contaminate surface and ground water, which was primarily thought to occur through surface runoff.

The team found that when air temperatures increased, so too did soil moisture’s role in influencing atmospheric losses – volatilisation – of these two chemicals, something that had not been considered or observed in earlier experiments. When soils were dry and air temperatures increased, there was no increase in herbicide volatilization, but herbicide volatilization increased significantly when temperatures rose and soils were wet.

According to the report, most surprising was that throughout the study, herbicide volatilization losses were significantly larger than surface runoff. When averaged over the two herbicides, loss by volatilization was about 25 times larger than losses from surface runoff. Read more here.

Wildfires spur emissions of greenhouse gases from soil

The Summit County Voice reports that an accidental bush fire during a climate change experiment revealed that wildfires can significantly increase the release of the environmentally-damaging gas nitrous oxide, which can, in turn, accelerate climate change.

“Soils are the major source of nitrous oxide in the atmosphere,” said Jamie Brown, graduate student in biological sciences at Northern Arizona University (NAU) and co-author of the study. “So increased soil emissions of nitrous oxide will accelerate global warming.”

Brown worked with other researchers from NAU, Stanford University, the University of Paris and the University of Lyon. Their experiments were based on an experimental grassland which was exposed to simulated and simultaneous environmental changes relating to heat, extra carbon dioxide in the atmosphere, more rain, more nitrogen deposition, and, when part of the experiment accidentally burned, wildfire.

“Alone, the treatments had little influence on nitrous oxide emissions, but what was really surprising was the interaction with wildfire, causing a huge burst of nitrous oxide production,” said NAU professor Bruce Hungate, Brown’s thesis adviser and co-author on the study.

“Increasing wildfire frequency and the changing climate could cause these soil micro-organisms to release more nitrous oxide into the atmosphere, accelerating global warming,” Brown said. Read the full report here.

Sunflowers may heal Fukushima’s radioactive soil

According to this report, activists in Japan are looking to sunflowers to help decontaminate soil affected by the Fukushima nuclear disaster. A group of civil servants and young entrepreneurs are asking people to grow sunflowers, then harvest and send the seeds to north-eastern Japan to grow in, and hopefully clean, the contaminated soils near to the damaged power station.

Japanese scientists have already conducted a test by growing sunflowers in the contaminated soil on farmland near the nuclear plant. Sunflowers have already been shown to germinate and sprout in this soil and if it is confirmed that the growing plants have absorbed significant quantities of radioactive caesium, scientists will use bacteria to decompose the plants into what will be classified as radioactive waste.

The report explains how the sunflowers can help: “The process of extracting contaminants from the soil via plants is called phytoremediation. While animals can move away from pollutants or other toxics (if they’re lucky), plants have evolved ways to live with the toxics and eventually extract them from the soil. The downside is that the concentrated pollutants, such as radioactivity or lead, can then pass along the food chain if not disposed of properly. Sunflowers were used to suck up radioactive caesium and strontium in a pond at the Chernobyl nuclear accident site in 1994 and to remove uranium from contaminated springs near the Oak Ridge (TN) National Laboratory in 1996.”

Growing plants with friendly fungi

As the UK bathed in a rain-free spring this year and global rainfall patterns are forecast to shift and alter, being able to maintain and increase food production with intermittent rainfall will become increasingly important. Researchers at the University of Exeter are looking at ways of tackling this problem by studying whether adding a safe and harmless fungus to compost boosts the growth and proliferation of crops' roots which can help them grow using less water.

The research, highlighted on the Biotechnology and Biological Sciences Research Council (BBSRC) website, also includes trials involving a supplier to a major supermarket brand which are investigating whether the plants exposed to the fungus can be grown in the absence of fertiliser too.

Dr Chris Thornton, one of the researchers, has been studying the growth promotion effect of the fungi in glasshouse-grown lettuce. "In the absence of fertiliser you still get an amazing growth increase with a five-fold improvement in root matter," says Thornton. "This is the first time we know of that it's been tried on brassica [broccoli and sprouts] plants in the field."

In addition, previous studies have shown that the fungus has properties as a natural biocontrol agent of pathogenic fungi and could reduce the need for synthetic fungicides. For more on the research, click here.

Soils and climate change

Two recent articles, one from Australia and one from the US, refer to sometimes contrasting attitudes in the debate about how best to manage soils effectively in the face of a changing climate.

In Cellulosic Fantasy: Ending Corn Ethanol Subsidies, writer Steve Breyman argues against the development of new technologies which will convert plant ‘waste’ into biofuels; specifically, cellulosic ethanol.   Apparently it’s currently harder, more expensive, and unprofitable to produce ethanol from cellulose (woody biomass) as compared to corn kernels but the US Department of Energy is reported to be supporting (with a $105 million loan guarantee) the expansion of an ethanol refinery in Iowa.

The New York Times states that commercial production of ethanol from waste products like husks is the ‘holy grail’ of the ethanol industry.   Professor Breyman, however, argues (quite rightly in my opinion) against this sort of technology on the basis that this so-called waste is of vital importance to the soil and contributes to maintaining and increasing soil organic matter (SOM) levels which help to reduce erosion and improve drainage and moisture retention.  Read more of what he has to say here.

The Australian government seems to be taking a different approach to its US counterpart, however, over how soils can help society deal with climate change.   To complement the carbon farming initiative  (which will allow farmers to earn credits for planting trees, reducing pollution from fertiliser and methane emissions from livestock), farmers stand to gain from $429 million-worth of funding into the best ways to store carbon in the soil and drive down pollution in the agriculture sector.

According to a report in The Australian newspaper, an additional $201m has been secured from the federal government to engage scientists and independent experts to develop ways to improve soil carbon storage and reduce emissions from livestock and crops.   Read the full story here.

Assessing Agroforestry's Advantages

Scientists in Wisconsin studying agroforestry have found that the use of trees in livestock and crop farming systems can help capture substantial amounts of carbon on agricultural land while providing production and conservation benefits. Questions exist, however, over exactly how much carbon such systems sequester.

Windbreaks in North America only occupy around 2% - 5% of farmland yet capture carbon as the trees develop. They also help protect crops and livestock, and reduce soil erosion.

Unlike forests, the linear design of windbreaks creates a more open environment with different light and climate conditions. Researchers have developed a model specifically designed to determine current or future amounts of carbon contained in agroforestry practices such as windbreak trees, and the model provides a good basis for determining agroforestry’s contributions in farming operations. Read the full report here.