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

The post Soil Health and Fertiliser first appeared on Kynoch Fertilizer.

As a wheat farmer in South Africa, you understand the importance of optimal soil preparation and fertilisation for a successful harvest. Soil testing and targeted fertilisers are crucial components of this process, helping you identify and address nutrient deficiencies to ensure healthy plant growth. In this article, we’ll delve deeper into the world of soil testing, nutrient deficiencies, and targeted fertilisers, providing you with the knowledge and resources you need to optimise your wheat farming operations.

Soil Testing: The First Step

Soil testing is the foundation of optimal “nutritional” soil preparation that should be done well in advance. It helps you determine the soil’s fertility status (including pH, cations, and phosphorus content, sulphur content, acidity, and silt and clay content, aka texture; as well as all trace elements), enabling you to make informed decisions about correctional fertiliser applications prior to planting, as well as the best suitable fertiliser to apply during planting. The latter will be determined by the soil status, as well as the crop demand, linked to expected yield potential. In the winter rainfall area of South Africa (Western Cape), it is also very important to measure the rock and coarse fragments in the soil sample. According to the Agricultural Research Council, soil testing every 3-5 years is recommended to monitor changes in soil health and adjust your management strategies accordingly (Agricultural Research Council, 2022). Kynoch advises testing every 3 years.

Common Nutrient Deficiencies in Wheat Farming

Wheat crops require a balanced mix of nutrients to thrive. In general, some of the most common nutrient deficiencies in wheat farming include:

1. Nitrogen (N): Essential for plant growth and development, nitrogen deficiency can lead to stunted plants, reduced yields, and poor grain quality.
2. Phosphorus (P): Crucial for root development, phosphorus deficiency can result in reduced plant growth, poor water uptake, and decreased yields.
3. Potassium (K): Important for plant water balance and disease resistance, potassium deficiency can lead to weakened plants, reduced yields, and increased susceptibility to disease.
4. Trace elements: Depending on soil conditions, deficiencies of micro-elements could be expected. If the soil is acidic, elements like molybdenum could be deficient; if the soil is sandy, elements like copper, zinc, boron, iron, and manganese could be deficient. If the soil is alkaline, basically all trace elements, except molybdenum, could be deficient.
5. Soil acidity: Wheat is very sensitive to soil acidity (expressed as acid saturation). It is imperative for wheat production to try and keep acid saturation at less than 1%. The only way to neutralise acidity is by applying agricultural lime, whether dolomitic or calcitic (depending on the soil’s calcium-to-magnesium ratio). Lime could be obtained from dedicated lime supplying companies.

Targeted Fertilisers: Addressing Nutrient Deficiencies

Targeted fertilisers are designed to address specific nutrient deficiencies, providing your wheat crop with the necessary nutrients for optimal growth and development. Mostly, some serious elemental deficiencies identified through the soil analysis done prior to planting could be rectified before planting by targeted fertilisers containing phosphorus, potassium, sulphur, and magnesium. An element like nitrogen will always be applied during planting, with the remaining portion applied just before planting (pre-plant application), or as a top dressing 4 to 6 weeks after emergence. The planting blend, consisting primarily of nitrogen, phosphorus, and potassium, will be made up of different ratios according to crop preference and soil conditions. For instance, in the Vaalharts-irrigation scheme, a 7:3:3 or 2:3:2 N:P:K-ratio fertiliser is popular. In the dry-land summer rainfall areas, a 4.1.0 or 8.2.1 N:P:K-ratio fertiliser could be used. In the winter rainfall area, MAP is a popular option.

Reputable Resources for South African Wheat Farmers

For further guidance on soil testing, nutrient deficiencies, and targeted fertilisers, consult the following reputable resources:

1. Agricultural Research Council – Small Grain Institute (ARC-Small Grain Institute)
2. Fertilizer Association of Southern Africa (FERTASA)
3. NviroTek Laboratories ((link unavailable))

You can find more information on these resources through online searches or by consulting with local Kynoch agricultural experts and extension services. Other laboratories in South Africa could also be found online.

Conclusion

Optimising soil preparation and fertilisation is critical for successful wheat farming in South Africa. By understanding the importance of soil testing, identifying common nutrient deficiencies, and applying targeted fertilisers, you can ensure healthy plant growth, improved yields, and enhanced grain quality. Remember to consult reputable resources for guidance and support, helping you make informed decisions for your wheat farming operations.

Note:

1. The article is written in a clear and concise manner, making it easy to understand, and is based on reputable sources. It is not intended to be an exhaustive or technical guide, but rather a helpful resource for South African wheat farmers and producers.
2. Wheat production and practices for the summer and winter rainfall areas differ from one another. Please note the differences in reference sources.

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The post Optimising Soil Preparation and Fertilisation for Wheat Farming first appeared on Kynoch Fertilizer.