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27 September 2021 | Story Leonie Bolleurs | Photo Supplied
Eddie Smit, Tercia Strydom, and Prof Johan van Tol testing the hydrophobicity of soils directly after an experimental fire.

The main driving force behind climate change is the emission of greenhouse gases through human activities, says Prof Linus Franke, Associate Professor and Head of the Department of Soil, Crop and Climate Sciences at the University of the Free State. 

“Carbon dioxide is the biggest culprit, accounting for 72% of the global warming effect, followed by methane and nitrous oxide.” 

Too much carbon in the atmosphere

Human activities are the main driver of climate change, mainly by burning fossil fuels such as coal, gas, and oil, with the energy sector, industries, transport, buildings, and agriculture as the biggest emitters of greenhouse gases. 

According to the United Nations, the burning of these fossil fuels generates greenhouse gas emissions that wrap around the earth like a blanket, trapping the heat of the sun and resulting in raised temperatures. According to Prof Franke, it is important to mitigate climate change and prevent a global temperature rise of more than 1,5 degrees Celsius. According to the Intergovernmental Panel on Climate Change (IPCC), we are looking at a temperature increase of around four degrees Celsius by the end of this century, if there are no drastic changes.

With an increase in global warming, we are expecting more disturbances in weather patterns, resulting in further extreme weather conditions such as droughts, floods, and extremely cold/hot conditions. Annually, millions of people lose their lives, livelihoods, and homes due to the effects of global warming.

“The latter has been predicted for a long time, but today it is a common phenomenon. Twenty years ago, climate change was about analysing trends in data sets. Today, to observe climate change, one can just look out of the window. In the past 10 years, climate change has become a reality,” says Prof Franke. 

Although carbon dioxide is one of the biggest contributors to global warming, it has an important role to play in soil health. 

Soil as a major sink of carbon

As plants absorb the carbon dioxide from the atmosphere, enormous amounts of carbon are stored as organic soil matter in the upper two metres of soil. Prof Franke says carbon in the top two metres of soil is 200 times more than the amount that is annually emitted by human activities and three times the amount that is present in the atmosphere or vegetation. 

“Carbon in soil plays an important but underestimated role,” he says. He believes that through proper soil management, humans can control the amount of carbon in the atmosphere. In the long term, this could have a positive effect on climate change.

“Our ultimate aim it to get sufficient amounts of carbon in the soil,” says Prof Franke. His department is involved in several studies to understand soil carbon and carbon sequestration processes. 

Odwa Malongweni collecting a soil sample from exclosures in the Kruger National Park.(Photo: Supplied)

Prof Johan van Tol, Associate Professor in the same department, and postgraduate students are conducting research in the Kruger National Park and the Drakensberg, where they are investigating the best ways to preserve carbon and increase the soil carbon levels. 

He is of the opinion that there are two viable options for storing carbon removed from the atmosphere: the soil and the oceans. “Of the two, storing carbon in the soil is more realistic for most people and companies, as ownership and management of this natural resource can be determined. The potential for storing carbon in the soil is vast, yet poor soil management has led to carbon emissions equal to that of burning oil and coal reserves. Good soil management and restoration of degraded soils, on the other hand, can result in considerable sequestration of atmospheric carbon,” he says. 

According to him, soil and environmental factors determine the carbon storage potential of the soil. He says in the mountainous soils of the Maloti-Drakensberg (MD), the cool climate and high rainfall have resulted in carbon-rich soils. “This area is generally considered a ‘carbon hotspot’, yet little is known about the carbon dynamics of these soils.”

Preliminary results from a project by two of his postgraduate students, Cowan Mc Lean and Jaco Kotze, titled Characterisation of carbon stocks, microbial diversity and degradation of the soils of the Amphitheatre summit, Northern Drakensberg, show that average carbon stocks of the soils are high to very high in the alpine wetlands. They found that poor land management (overgrazing) has resulted in soil and land degradation (e.g., erosion, draining of wetlands, and loss of vegetation and biodiversity). 

“The degraded soils are no longer a ‘sink’ of atmospheric carbon, but become a ‘source’ that releases carbon,” he states. 

He says drastic action is required to restore and protect these important carbon hotspots. 

Today, to observe climate change, one can just look out of the window. In the past 10 years, climate change has become a reality. – Prof Linus Franke
In a study in the Kruger National Park, PhD students Tercia Strydom and Odwa Malongweni are investigating the impact of fires and herbivores on soil quality, including carbon contents. “They found that soil carbon is significantly impacted by fire and herbivores. The changes in vegetation structure due to fire and herbivores are likely to be the key driver of changes in carbon stocks,” says Prof Van Tol. 

An agricultural perspective 

Prof Franke considers carbon as an essential element for farming. “It is important for a healthy farming system,” he says. 

He is conducting a study on high-density grazing, funded by the Regional Universities Forum for Capacity Building in Agriculture. The on-farm performance of different grazing management systems, including selective and high-density grazing, with special reference to the spatial and temporal dynamics of soil carbon, is investigated in this study. 

The research indicates that the grassland biome of South Africa covers about 20% of South Africa’s land surface, with more than half of the biome converted to arable land or greatly disturbed by urban development mining activities. The remaining tracks of the grassland biome are mostly used for livestock grazing on natural grassland. 

 

Prof Johan van Tol, Sue van Rensburg from the South African Environmental Observation Network, and Prof
Linus Franke in the Drakensberg. (Photo:Supplied)

 

He says there are different grazing management strategies of natural grasslands. “In continuous grazing systems, animals are given the opportunity to graze all season long with minimal interference. Rotational grazing systems incorporate periodic deferments, allowing field vegetation to recover in the period when grazing is absent. 

“The more recent strategy of high-density grazing uses large herds, often double or triple the normal stocking densities for an area, grazing intensively on small areas of land for a short period of time, followed by a long resting period of the field.”

“High-density grazing is claimed to improve rangeland productivity by improving soil health, increasing soil carbon stocks to an extent that the emissions of greenhouse gases by livestock may be compensated by soil carbon sequestration, and improving the condition of the vegetation, while enhancing animal productivity on a per area basis. The adoption of high-density grazing can have major impacts on the sustainability and the economics of livestock production. An aim of the research is to quantify to what extent the claims of increasing soil carbon levels under high-density grazing realise under on-farm conditions,” explains Prof Franke.

He trusts that the knowledge generated in this project will be helpful to the broader agricultural sector, providing knowledge on carbon cycling, environmental sustainability, and opportunities for climate change mitigation in the livestock production sector.

Prof Franke is convinced that the protection of grasslands against degradation, while ensuring sufficient, reliable, and sustainable food production, are absolute key components driving the national and global development agenda.


Prof Johan van Tol taking a soil sample on top of the Drakensberg. (Photo: Supplied)

News Archive

Professor’s research part of major global programme
2011-04-04

 

Prof. Zakkie Pretorius, professor in Plant Pathology in the Department of Plant Sciences at our university

Research by Zakkie Pretorius, professor in Plant Pathology in the Department of Plant Sciences at our university, has become part of Phase II of a mayor global project to combat deadly strains of a wheat pathogen that poses a threat to global food security.

Prof. Pretorius focuses on the identification of resistance in wheat to the stem rust disease and will assist breeders and geneticists in the accurate phenotyping of international breeding lines and mapping populations. In addition, Prof. Pretorius will support scientists from Africa with critical skills development through training programmes. During Phase I, which ends in 2011, he was involved in pathogen surveillance in Southern Africa and South Asia.
 
The Department of International Development (DFID) in the United Kingdom and the Bill and Melinda Gates Foundation will invest $40 million over the next five years in the global project led by the Cornell University. The project is aimed at combating deadly strains of Ug99, an evolving wheat pathogen that is a dangerous threat to global food security, especially in the poorest nations. 
 
The Cornell University said in a statement, the grant made to the Durable Rust Resistance in Wheat (DRRW) project at Cornell will support efforts to identify new stem-rust resistant genes in wheat, improve surveillance, and multiply and distribute rust-resistant wheat seed to farmers and their families.
 
Researchers worldwide will be able to play an increasingly vital role in protecting wheat fields from dangerous new forms of stem rust, particularly in countries whose people can ill afford the economic impact of damage to this vital crop.
 
The Ug99 strain was discovered in Kenya in 1998, but are now also threatening major wheat-growing areas of Southern and Eastern Africa, the Central Asian Republics, the Caucasus, the Indian subcontinent, South America, Australia and North America.
 
Prof. Pretorius was responsible for the first description of this strain in 1999.
 
Among Cornell’s partners are national research centres in Kenya and Ethiopia, and scientists at two international agricultural research centres that focus on wheat, the Mexico-based International Maize and Wheat Improvement Center (known by its Spanish acronym as CIMMYT), and the International Center  for Agricultural Research in the Dry Areas (ICARDA), in Syria. Advanced research laboratories in the United States, Canada, China, Australia, Denmark and South Africa also collaborate on the project. The DRRW project now involves more than 20 leading universities and research institutes throughout the world, and scientists and farmers from more than 40 countries.


Media Release
28 March 2011
Issued by: Lacea Loader
Director: Strategic Communication
Tel: 051 401 2584
Cell: 083 645 2454
E-mail: news@ufs.ac.za

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