Improving soil quality for a sustainable food production

How to increase sustainable food production in a hotter and drier climate for a constantly growing population while soil is protected?

Throughout the past century, advancements in agricultural technology have allowed farmers to feed a human population in constant growth and this has contributed to a huge deterioration of soil quality and health.

A frequently cited definition of soil health comes from Doran et al. (1996): ‘soil health is] the continued capacity of soil to function as a vital living system, within ecosystem and land use boundaries, to sustain biological productivity, maintain the quality of air and water environments, and promote plant, animal, and human health’. This definition represents an integration of biological, physical and chemical domains (Idowu et al., 2008), reflecting a recent emphasis on soil as a living system.

As stated by the USDA Natural Resources Conservation Services (NRCS) 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 ”. Soil health for a farmer is directly linked to plant yield but it has other advantages. Healthy soils produce more nutritious food and give plants greater resilience to pests and diseases. Healthy soils also hold more water, making this available to plants when rainfall is unreliable, or absorbing more during heavy rains, preventing floods and the run off of vital nutrients from fields.

In most ecosystems, more life and diversity lives underground than above. Soil organisms such as bacteria, fungi, protozoa, nematodes, arthropods, and earthworms play critical roles such as decomposition, mineralization , pollutants degradation, carbon and nitrogen cycling , amongst others. The rhizosphere is the location of much soil biological activity and plant microbe interactions including symbioses, pathogenic infection, and competition. The types of species present and their level of activity depends on micro environmental conditions including temperature, moisture, aeration, pH, pore size, and types of food sources.

Plant pest dynamics depend on the whole mix of organisms in the soil. Some organisms prey on or compete with disease causing organisms. Some bacteria release plant growth factors that directly increase plant growth.

So, how we can increase the food production in a sustainable way for the humans and the environment while we protect the soil health?

  • Measuring soil quality: physical, chemical, and biological properties of the soil.
  • Minimize soil disturbance like tillage and return plant residues to the soil  rebuilding the stock of soil organic matter , preventing loose soil particles, increasing biodiversity and bioactivity, protecting the network created by mycorrhizal fungi.
  • Reduce the use of unnecessary nutrient fertilizers by monitoring regularly the nutrients in soil before making applications.
  • When working with biologicals (living organisms) to control a pest , treat a disease or biostimulants plant physiology, the impact in the existing ecosystem should be analysed. The use of biologicals is different than working with chemicals where actions/effects can be more easily predicted. Interaction occurs in a very complex way, adding species can provoke the increase or decrease on existing species, beneficial or not, so u npredictable effects can occur. Partners in the soil change over the time and plants select each time the best microbiome when it is available , so this should be considered on a case by case basis to allow biologicals to success in the future.
  • When pesticides are needed, the use of less (eco)toxic substances are preferable to avoid impacts on the soil microbiome and the microbially mediated processes that affect soil functioning.

We need urgently awareness of good agricultural practises, as soil health has the power to improve plant, human and animal health (“One Health” concept”) so we can find together the best way to take advantage of this.

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