Optimising soil health in row crops and orchards

Written by Bates Booyens (Cert.Sci. Nat)

Regional and Technical Manager - Western Cape North

South Africa has limited available land for food production and it is therefore of the utmost importance that we nurture our soil resource. The way in which we manage our soil can either improve or degrade the quality of the soil.

Soil health refers to the ability of the soil to continually provide multiple functions to sustain plants, animal, and human lives. Healthy soils according to the FAO¹, maintain a diverse community of soil organisms that help to control plant diseases, weed and insect pests. These soil organisms form beneficial symbiotic associations with plant roots, recycle essential plant nutrients and improve soil structure.

Improved soil structure has positive repercussions for soil water and nutrient holding capacity and thus improve crop production. A healthy soil provides functions that support plant growth, including nutrient cycling, biological control of plant pests, and regulation of water and air supply. These functions are influenced by the interrelated physical, chemical, and biological properties of soil, many of which are sensitive to degradation due to soil management practices.

Soil health functionality

Soil health functionality is highly influenced by soil organic matter. This soil property influences soil physical, biological, and chemical functions (2). Physical properties include aggregate stability, water holding capacity and water infiltration. Biological properties refer to the concentration and composition of organic matter, micro-organisms and macro-organisms. Chemical properties include pH levels, macronutrients, micronutrients, toxicity, and salinity.

Healthy soils are thus more capable to cope with less ideal growing conditions. The crops’ capacity (row or permanent) to withstand weather variability (short-term extreme precipitation events and intra-seasonal drought) increase in healthy soils (3).

Soil health challenges

Soil health challenges include high levels of disease incidence and pests, which can cause damping-off, root rot, and vascular wilt, among other symptoms. Other challenges include no topsoil or low organic matter, heavy (clay) soil, compaction, and poor drainage. Erosion and slopes, rocks, buried debris, and obstructions, incorrect soil pH and low nutrient levels, lithologic discontinuity (distinct changes in particle size between soil layers) and soil temperature are also challenges (4).

Agricultural management practices should focus on reducing erosion, increase of nutrient use efficiency, improving soil structure, and sustaining or increasing yields. Pest and disease management are also a component of a soil health management system (5). Examples include planting cover crops, applying mulch, liming acidic soils to improve soil pH, biological control of pest organisms, manage nutrients, and correct tillage practices based on soil characteristics, to name a few.

Conclusion

In conclusion, soil health is important to farming. Soil health, however, does not only refer to the biological soil fraction, but encompasses the total soil’s physical, chemical and biological health. Healthy soil supports healthy plant growth, reduces runoff and erosion, while water infiltration is maximised, nutrient cycling is improved, and soil tilth is improved. In the end, management for soil health saves money-primarily on reducing inputs (diesel, fertiliser, and pesticides) and creates a more robust environment. Healthy soil is thus the foundation of productive, sustainable agriculture. Sustainable agricultural practices have further major benefits on soil health, including improved carbon sequestration and water retention.

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Optimising soil health in row crops and orchards

Written by Bates Booyens (Cert.Sci. Nat)

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