It’s no secret that soil, a heady mix of rock particles, decaying organic matter, roots, fungi and microbes, is essential to the production of more than 95% of the world’s food.

Yet global agriculture – plowing, terracing and relying on inorganic fertilisers – is destroying this life-giving resource. And this is a problem that’s becoming worse with each passing year.

Causes

Soil is a vital natural resource that helps produce more than 95% of the world’s food. It contains rock particles, decaying organic matter, roots, fungi and microorganisms that help plants grow.

In addition to providing nutrients for crops, soils help sequester 80% of the planet’s carbon. Healthy soils absorb huge amounts of greenhouse gases and are the most powerful form of carbon capture on earth.

However, a global average of 13.5 tonnes of soil is being degraded each year, causing many problems for farmers and the environment alike. This degradation is resulting in soil erosion and the loss of fertile topsoil that would otherwise nourish crops.

In addition, some disease-causing fungi are spreading outside their historical ranges. For example, Histoplasma, the fungus that causes histoplasmosis, has been found in areas that are far outside its endemic range. Its expansion is also being linked to climate change. Other fungal diseases such as coccidioidomycosis, or valley fever, and blastomycosis are also expanding beyond their historic zones.

Symptoms

The virgin soil epidemic has got to be the most widespread human-caused disease in history. While this type of disease is not contagious, it still kills most of the afflicted population. A lucky few get a shot at immunity by surviving long enough. There is a catch though–virgin soil epidemics are not very likely to occur in the first place.

The best way to avoid such an event is by following a sound crop management plan based on research and development. The key is to maintain a balanced crop and a healthy soil microbiome. It may not be easy, but the reward is well worth the effort.

Treatment

Soil disinfestation is a technique used to reduce pathogen populations to the desired level before planting by applying an agent that penetrates into the soil. Typically this is a fumigant or a biocontrol agent.

In practice, it requires adjusting an appropriate dosage to control pathogens while not damaging desirable biotic and abiotic components of the soil. This adjustment needs to be made for each soil, crop, and agricultural system.

The treatments can be carried out in a variety of ways and may include sprays, dusts, and soaking. They can also be applied to seed as thick water suspensions mixed with the seed.

To prevent recontamination, plant only disease-free seed in the treated soil. This is important because many diseases can be carried on the seeds of the planting material.

Prevention

A healthy soil is a vital part of any cropping system. It provides tilth, drainage and nutrient supply to plants, and is also an excellent carbon sink.

Soils are inhabited by micro and macro-organisms that regulate the properties of the soil and help plants grow. These organisms play an important role in disease prevention and suppression by limiting pathogen activity.

Despite this, the most pronounced pathogens can be difficult to control. These organisms can reduce crop yields, increase cost to the grower and cause ecological damage.

The best way to prevent soil-borne diseases is to manage the existing microbes in the soil, and if possible remove or minimize host plants from areas of high risk. Other management tools include crop rotation, adequate aeration and drainage of the soil, and practices such as compost application and solarization.