The multifunctionality of this phenomenon is evident in its roles in nutrient cycling, biological pest control, and the regulation of water and air availability, which are influenced by a combination of physical, chemical and biological factors.

The multifunctionality of this phenomenon is evident in its roles in nutrient cycling, biological pest control, and the regulation of water and air availability, which are influenced by a combination of physical, chemical and biological factors.

The complex relationship between soil health, water quality, and climate change can involve multiple perspectives, resulting in a complicated theoretical mixture.

This overview focuses on farmers and their soil at grassroots level, with sustainability in mind within our practical reality. What steps can the farmer take to begin improving soil health?

Add organic matter to the soil
In South Africa, the levels of organic matter in soils are very low, with approximately 58% of soils containing less than 0,5% organic carbon. The amount of organic matter varies depending on factors such as climate, vegetation, topography and soil texture.

Increasing the organic matter in the soil will have direct and indirect benefits for soil quality. Microbes break down plant residues in the soil to convert them into carbon.

The availability of inorganic nitrogen, soil water conditions, and temperature all have an impact on the rate of decomposition. Increased cultivation can lead to a faster breakdown and depletion of carbon. Therefore, it is recommended to minimise tillage and promote root growth by using seaweed extracts, adding calcium, magnesium, zinc and boron, as well as using humic acid (liquid carbon).

Micro-organisms in the soil
There are two main approaches that could be followed:

Add microbes to the soil: Adding microbes to the soil can have beneficial effects. This can be achieved by using granular fertiliser that is coated with microbes, applying organic material that contains microbes, or using liquids that contain microbes. Dry products can be spread evenly over the soil or placed in specific areas.

Feed microbes already in the soil: There is a large population of micro-organisms in the soil, estimated to be around 100 billion per gram of soil. When plant roots are in the soil, they come into contact with these microbes. The highest activity of microbes is typically found in the top 20cm of soil. Therefore, it is beneficial to provide carbon sources such as humic acid and fulvic acid to feed these microbes.

Add ‘housing’ for microbes
Carbon, such as biochar, organic roughs, or humic acids, can be utilised as a soil amendment to enhance crop growth by regulating soil conditions. This is due to its distinctive qualities, including a large surface area, a rich pore structure, an abundance of oxygen-containing functional groups, and a high cation exchange capacity.

Spray microbes on plants
Each plant possesses a microbiome that consists of fungi, viruses and bacteria, which play crucial roles in the plant’s functioning and survival. These micro-organisms can be found in various areas, such as the root zone (known as the rhizosphere), the internal environment of the plant (endosphere), and the above-ground surfaces (phyllosphere).

Farmers have the option to introduce microbes to the plant’s above-ground growth through foliar sprays or to the soil through soil drenches.

Irrigation
The practice of wetting soil profiles and subsequently withholding water for an adequate duration to facilitate the re-establishment of oxygen in the soil is considered a beneficial approach, as it effectively mitigates the occurrence of prolonged anaerobic conditions.

Conclusion
Lastly, it is worth noting that crop rotation is a highly effective management strategy that exerts a significant influence on microbial diversity within the soil.

Author: Dr Chris Schmidt

The post Soil health: a multi-perspective conundrum first appeared on Kynoch Fertilizer.

Regular soil testing is crucial for monitoring the status of the soil solution.

When discussing crop nutrition, the focus is often on soil nutrient levels. However, many processes and interactions occur in the soil solution, which is a dynamic mixture of water, dissolved nutrients, minerals and organic compounds present in the soil’s pore spaces.

The soil solution plays a crucial role in delivering nutrients to plant roots, supporting biochemical processes and facilitating the uptake of essential elements. Key factors affecting the soil solution include:

SOIL PH

The soil pH influences nutrient availability and mineral solubility. Outside the optimal range, certain nutrients become less soluble while others may become toxic. Acidic soils reduce the availability of nutrients like phosphorus, calcium and magnesium while increasing the solubility of toxic metals like aluminium and manganese. Alkaline soils limit the availability of essential micronutrients like iron, zinc, and manganese.

SOIL TEXTURE

The proportion of sand, silt and clay particles affects water and nutrient retention. Sandy soils have larger particles and fewer binding sites, which leads to poor nutrient retention and a higher risk of nutrient leaching.

Clay soils have fine particles and high nutrient-holding capacity but can sometimes retain nutrients too tightly, limiting their availability.

CATION EXCHANGE CAPACITY

Cation exchange capacity (CEC) is a measure of a soil’s ability to hold and exchange positively charged ions (cations) like potassium, calcium and magnesium. Soils with a higher CEC (typically clay or those rich in organic matter) can hold more nutrients, making them available to plants over time. Low-CEC soils (usually sandy soils) have a lower nutrient-holding capacity, leading to more frequent nutrient deficiencies.

SOIL STRUCTURE

Well-structured soil has better aeration and allows for easier root penetration, facilitating nutrient access. Compacted soil, on the other hand, can restrict root expansion and reduce nutrient uptake.

ORGANIC MATTER

Organic matter, including compost and decomposed plant material, enriches the soil solution by increasing nutrient availability and improving soil structure.

As organic matter decomposes, it releases nutrients into the soil solution and enhances the soil’s ability to retain water and nutrients, which benefits plant roots.

SOIL MOISTURE

Water is the medium through which nutrients are dissolved and transported to plant roots. Excess moisture can cause the leaching of nutrients, especially nitrogen. Lack of moisture reduces the solubility and movement of nutrients, limiting plant uptake.

SOIL MICROBIAL ACTIVITY

Micro-organisms in the soil play a crucial role in nutrient cycling. They break down organic matter, fix atmospheric nitrogen, and solubilise phosphorus and other nutrients, making them available to plants. Healthy soils with active microbial communities promote faster nutrient cycling and greater nutrient availability in the soil solution.

SOIL COMPACTION

Compacted soil has reduced pore spaces, limiting water infiltration, air movement, and root penetration. This can impede the movement of nutrients in the soil solution and restrict the plants’ access to them.

TEMPERATURE

Warmer temperatures generally increase microbial activity, speeding up nutrient cycling and availability. Cold soil slows down microbial processes and reduces nutrient availability, especially nitrogen mineralisation.

NUTRIENT INTERACTIONS

Fertilisation aspects – such as frequency of application, nutrient concentration, chemical form, and nutrient solubility – need to be considered. Enhancing the soil solution can significantly improve nutrient availability, ensuring plants have access to the essential elements they need for optimal growth and productivity.

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011 317 2000, or visit kynoch.co.za

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