Healthy soil is a key driver of farm productivity, profits and sustainable food production. Dr. Hendrik Smith explained to Magda du Toit how farmers can improve the health and fertility of their soil.
The biggest threat to South Africa’s farmland does not come from the global economy or government policies. It is found under the feet of the farmers.
According to conservation agriculture advocate Dr. Hendrik Smith, 95% of food production relies directly or indirectly on soil. However, this resource has long been taken for granted, and a large percentage of agricultural land is moderately or severely degraded due to years of neglect or misuse.
The good news is that, in many cases, the situation can be reversed by changing production practices and rebuilding the soil. Healthier soil will not only ensure food production, even in less than ideal conditions, it will restore biodiversity and reduce carbon emissions. Carbon sequestration capacity is enhanced by nurturing soil health and photosynthetic capacity through good soil management.
“If soil health is neglected, less carbon will be stored in the soil. This will have a detrimental effect on the environment and could accelerate global climate change,” Smith emphasized.
Soil erosion is a major environmental problem affecting land and water resources in South Africa. Although a natural process, it is accelerated by human activities such as clearing vegetation, tillage and overgrazing.
READ The role of conservation agriculture in reducing soil erosion
Soil erosion has many adverse effects locally and externally, such as reduced soil fertility, lower water quality and lower yields. It leads to the loss of fertile soil and reduced soil productivity, but it is also associated with the release of sediments into rivers, causing sedimentation and pollution of water resources.
In humid areas, erosion by water flow is more common, while in arid and semi-arid areas, wind is the main culprit.
Conservation and precision farming practices can help sustain current food production. Practical components of the entire agricultural production system can be achieved by adopting site-specific and component conservation plans.
Conservation practices should include no-tillage or reduced tillage that leaves post-harvest crop residues to cover the soil surface, and cover crops, crop rotation and livestock integration, construction of grasslands, terraces and buffer strips, and pasture erosion control systems. including with manure application and soil testing.
Regenerative conservation agriculture provides a comprehensive approach to soil and crop management, promoting the long-term sustainability of agricultural systems in terms of profitability and resource management. This farming philosophy is based on nurturing the health of the soil.
Test the soil
Proper and regular soil analysis is one of the keys that can open the door to proper soil management and increased production. The data obtained can be used to adapt soil management and agronomic practices according to specific needs.
Crops grow in a variety of soil types, so fertilizer needs will depend on the health and condition of the soil. The first step to healthy crop production should be to balance the soil, which requires regular soil analysis to determine the exact nutrient composition and pH level.
READ Summon your army of soil microbes and win the battle for profit!
Improper application of nutrients can cause soil imbalance and eventually affect the environment and even pollute water.
Farmers should also analyze the nutrients of each crop. Different crops in a rotation system have different nutrient requirements and may have different critical nutrient levels. A soil test and leaf analysis will determine the nutrient needs of the crop.
In addition, each crop has a different rate of nutrient removal, and knowing this helps determine a fertilization strategy.
By performing simple surface and subsurface analyses, early interventions can be planned and prioritized. It is always better to have a proactive strategy than a reactive one. Unplanned reactive interventions can lead to wasting money on unnecessary fertilizers or additional nutrients.
According to Smith, excessive application of nitrogen fertilizers is largely responsible
for many cases of rapidly increasing soil acidity. An increase in soil acidity dramatically inhibits root and plant growth and reduces the soil’s ability to withstand irregular rainfall or prolonged droughts.
Soil biology has a direct impact on soil structure and chemistry in determining the extent to which nutrients are bioavailable. Excessive levels of certain elements can have a detrimental effect on soil biology.
Although cover crops are not necessarily grown for profit, they are beneficial in many other ways. The roots of cover crops create channels in the soil that improve their ability to absorb water. Cover crops also build soil organic matter, help maintain soil and prevent erosion, and feed soil organisms that provide valuable nutrients to regular crops during the growing season.
According to Smith, the use cover crops It can increase the canopy and ground cover of the soil crop, and the presence of permanent and strong root systems greatly improves the soil’s resistance to erosion. Cover crops also allow the sustainable integration of livestock, which facilitates the creation of organic matter in the soil.
Ultimately, the proper application of conservation agriculture leads to a higher level of organic matter in the soil and this can be the key to stabilizing production areas against the destructive effects of erosion and climate change.
Organic matter content
Organic matter content is essential for the physical, biological and chemical functions of the soil, and is a key factor in governing soil health and productivity. This organic matter is made up of plant and animal remains in various stages of decomposition, and is approximately 50% carbon.
It is said that for every 1% increase in organic matter, the soil extracts 10 times more carbon from the atmosphere and adds 140 000 ℓ of water/ha.
“Research has shown that increasing soil carbon content not only significantly improves resilience to drought and erosion from heavy rainfall, but also allows the soil to retain more water, which is then readily available for plant growth and micro-organisms.
“Truncation is one of the biggest problems faced by farmers, as it can be a great obstacle to the infiltration of water and roots. Water must penetrate the soil to lower the surface water table, promote deep rooting and create optimal living conditions in the soil. Improving water retention also helps offset drought,” says Smith.
Increasing crop biodiversity
Plant or crop diversity helps break disease cycles and provides habitat for pollinators and soil-dwelling organisms.
Biodiversity-rich ecosystems are more resilient and recover more quickly from stresses such as climate extremes, human impact and land degradation. A healthy agroecosystem contains a variety of living organisms, including bacteria, fungi, nematodes, insects and earthworms.
Soil also contains many living microorganisms. These help manage soil structure, plant diseases, insects and pests. They also form beneficial symbiotic associations with plant roots, nutrient cycling and carbon storage.
Crop rotation systems reduce pests and diseases of certain plant species, build the health of soil microbes that provide nutrients to crop plants, and ultimately improve yield.
Animal grazing on land helps recycle nutrients across the landscape. By controlling where livestock graze, a farmer can add valuable nutrients and organic matter to the land and ultimately the soil.
The role of insects
The beneficial role of insects in agriculture should not be underestimated, and this is especially true of beetles. As these remarkable little recyclers go about their daily business of breaking down and distributing excrement, they offer many benefits to nature.
Dung beetles It plays a vital ecological role by washing away the excrement of large animals and returning essential nutrients such as phosphate, nitrogen and carbon, thereby increasing soil fertility which promotes plant growth.
In addition to building soil nutrients and fertilizing the soil, beetles increase soil organic matter and aerate and mix the soil by burrowing. These soil amendments improve water holding capacity and nutrient availability, both of which benefit plants.
The activities of dung beetles distribute the plant seeds contained in the droppings and keep pest and parasite populations under control, saving the livestock industry millions of rands each year.
“They are especially important on a farm if the populations are quite large,” says Smith. “They offer a self-contained solution to reduce surface emissions of methane gas and polluting manure, thereby improving water quality, soil health and pasture productivity.”
Email to: Hendrik Smith [email protected].