Soil Health and Fertiliser

Mankind is dependent on the soil for its needs for food and fibre for humans, feed for livestock, and, of late, contributing to our energy supply with crops grown primarily for biofuels. Soil is a dynamic and multifunctional living system that exists as a relatively thin layer on the Earth’s crust. (Singh & Ryan 2015).  Soil is not an inert growing medium – it is a living and life-giving natural resource. It is teaming with billions of bacteria, fungi, and other microbes that are the foundation of an elegant symbiotic ecosystem (USDA).

Soil health is defined as the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans (USDA).

As world population and food production demands rise, keeping our soil healthy and productive is of paramount importance. By farming using soil health principles and systems that include no-till, cover cropping, and diverse rotations, more and more farmers are increasing their soil’s organic matter (SOM) and improving microbial activity. As a result, farmers are sequestering more carbon, increasing water infiltration, improving wildlife and pollinator habitat—all while harvesting better profits and often better yields (USDA).

Soil Organic Carbon (SOC) found in the living matter in soils acts as a sink that traps and stores CO₂ – a major contributor to global warming. Soils represent the largest terrestrial pool of carbon: each hectare can store up to 50 – 300 tonnes of carbon (UNCCD 2014).

By increasing crop yields and productivity on available arable land, fertilisers help protect carbon-rich forests, peatlands, wetlands and grasslands by minimizing land use changes. Increased productivity through fertiliser use has spared 1 billion hectares of virgin land from cultivation between 1961 and 2005 and saved the equivalent of 317 – 590 billion tonnes of CO₂ emissions (the same as total global pre-1800 CO₂ emission levels) (Burney et.al. 2010).

With better management, farmland soil could also store up to an extra 1.85 billion tonnes of carbon each year (7 billion tonnes of CO₂): around the same amount of CO₂ emitted every year by the global transport sector (Zomer et. al. 2017).

The best way to capture more carbon on farmland is to use fertilisers to optimize plant growth and yields and leave crop residues in the field after harvest.

For every 2 – 3 tonnes of carbon stored above ground in plants, one (1) or more tonnes of carbon are generally stored below ground in the roots and root exudates.

Applying fertilisers following the 4R nutrient stewardship principles (Right nutrient source at the Right rate, at the Right time and in Right place) enhances nutrient use efficiency, which reduces nutrient losses to the environment, including in the form of greenhouse gases. Effective and efficient fertilization is a vital part of the climate-smart agricultural practices that could reduce global emissions by 5.5 to 6 billion tonnes of CO₂ equivalent per year: around the same as removing 1,500 coal-fired power plants from the energy sector (Smith et. al. 2007).

To help fight climate change we need to use fertilisers globally to grow more crops on existing farmland to protect carbon stored in wild ecosystems and increase the carbon stored in our agricultural soils (IFA 2018).

References:

• Bijay Singh and John Ryan 2015. Managing Fertilisers to Enhance Soil Health. First edition, IFA, Paris, France, May 2015. Copyright 2015 IFA.
• International Fertiliser Association (IFA) 2018. Integrated Plant Nutrient Management
• Jennifer A. Burney, Steven J. Davisc, and David B. Lobella, 2010.  Greenhouse gas mitigation by agricultural intensification.  Proceedings of the National Academy of Sciences (PNAS), June 15, 2010 107 (26) 12052-12057.
• Smith, P., D. Martino, Z. Cai, D. Gwary, H. Janzen, P. Kumar, B. McCarl, S. Ogle, F. O’Mara,  C.  Rice, B. Scholes, O. Sirotenko, 2007: Agriculture. In Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds)], Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
• UNCCD (2014) The land in numbers: Livelihoods at the tipping point. 2014. Secretariat of the United Nations Convention to Combat Desertification ISBN: 978-92-95043-90-9
• United States Department of Agriculture: Natural Resources Conservation Service: Soil Health.
• Zomer, R.J., Bossio, D.A., Sommer, R., & V. Verchot, (2017). Global Sequestration Potential of Increased Organic Carbon in Cropland Soils. Sci Rep 7, 15554.

Author: Graham Peddie from Kynoch Fertilizer

 

Soil Health in Sustainable Agriculture