Guest Post By Shaista Karim, 2021-2022 Sustainability Leadership Fellow and Ph.D. Candidate in the Department of Agricultural Biology at Colorado State University
We are in a continuous war with the dirt beneath our feet to grow food to feed the rising population. This dirt, called “soil” by those who know it well, often goes unnoticed but is the key to sustaining all life on Earth. Soil is home to thousands of plants, animals, and other important organisms which support numerous ecosystems. According to the Soil Science Society of America, “soil is defined by the combination of minerals, air, water, arthropods, animals and other living organisms that accumulate in layers and compact over time”. The world grows approximately 95% of its food in the uppermost layer of soil, or “topsoil”, making this layer one of the most important components of our food system. Without healthy soil, we cannot produce sufficient food to feed the rising population. Unfortunately, soil health has not been a priority in past farming practices, which has led to degradation of soil health. If we don’t put a higher value on the soils that nurture our crops, we could be facing an acute hunger throughout the world very shortly.
In the twentieth century, frequent mechanical tillage, pesticide application, and chemical fertilizer have made the topsoil very degraded for example, reduction of soil biota, both biomass and diversity. Sadly, our farming communities have developed a mindset that if we don’t put fertilizer on our lands, nothing grows. We aim to get higher and higher yields but in reality, we are ignoring the long-term effects, which include the release of greenhouse gasses and depletion of nutrients necessary for sustainable production. For example, the dead zone which is an area with low to no oxygen in the Gulf of Mexico was developed due to an alga bloom. This was trigged by supplementing soils with fertilizers high in nitrogen resulting in death of fishes and other aquatic animals. Therefore, immediate action is needed to minimize soil degradation which is critical for achieving sustainable agriculture and food security.
When will we stop tripping over our own Feet?
The Green Revolution achieved greater production by introducing high-yielding varieties, use of pesticides, and better management practices. It was driven by the fear that we would not be able to meet the food demand of the rising population in the early 1960s. We did produce more food but compromised the long-term health of the soil. The mass degradation of soil began by introducing technological advances in the early twentieth century. Farmers started to use chemical products to fight pests and diseases, and fertilizers to produce even more crops. Given that it takes 100 years to produce 1 to 2 centimeters of a soil surface layer packed with minerals, organic matter, and microorganisms, the soil should be considered a non-renewable resource. The strategic importance of soil for economic growth, environmental health, food security, and human development further makes the protection of soil health non-negotiable.
Sustainable land management was defined by the UN 1992 Rio Earth Summit as “the use of land resources, including soils, water, animals and plants, for the production of goods to meet changing human needs, while simultaneously ensuring the long-term productive potential of these resources and the maintenance of their environmental functions”. Many practices can be changed and or reversed to minimize soil degradation. This may include simple acts such as leaving vegetation on the soil, which allows nutrients to return to the soil and reduce soil erosion. Action to prevent, reduce and reverse the degradation of the region’s soils has the potential to improve food and water security which then contribute to climate change adaptation and mitigation. Therefore, there is an urgent need to develop practices that improve soil resistance or resilience to disease.
“If you had a handful of soil, you’d have more organisms than people on earth,” says Rob Myers, a soil scientist at the University of Missouri. Soil-dwelling microorganisms are critical components of soil health, itself a determinant of plant productivity and stress tolerance. Because these same microbes can contribute to restoring soil health and productivity, they have a bright future in sustainable agriculture that extends beyond more classically defined plant-microbe symbioses.
For example, some soil microbes (bacteria and fungi) are vital for organic matter decomposition. Likewise, some microbes form a relationship with plant roots and provide essential nutrients like phosphorous and nitrogen and some colonize on upper parts of plants and provide many benefits including resistance to plant disease, drought, and heat tolerance. Therefore, soil microbiomes play a vital role in mitigating diseases and environmental stresses.
Recent advancements in science introduced vital tools to identify species that are key components to soil and plant health, and therefore can be enriched in the soil. We are in dire need of these resilient tiny partners to help build a sustainable agriculture system and to stabilize the food-supply demand chain in areas of rapidly increasing human populations. Despite their size, soil microbes will ultimately help us to maintain our health and well-being. We must use scientific tools to understand, isolate, and foster microbial species into the soil to repair the damage and restore healthy microbial communities that sustain our crops and provide nutritious food.
Microbial supplements as a scaffold for soil healing strategies
Enrichment of beneficial microorganisms in the soil, together with the organic matter they feed upon has the potential to be a key part of the next big revolution in human health. The development of sustainable agriculture and food security relies on restored soil health. A multi-state collaborative research project is underway to explore how different crop management practices across the United States influence soil microbiomes to enhance crop production (https://potatosoilhealth.cfans.umn.edu/about). The aim is to identify and develop physical, chemical, and biological indicators of soil health for sustainable production using potato as a model crop. This will be accomplished by evaluating alternatives such as biological control and or crop rotation selecting to suppress soil-borne disease. These results will aid in developing predictive models which will help to establish strategies to overcome barriers and promote the adoption of alternative practices through effective extension and outreach programs. Through these findings, we believe we can get closer to the vital goal of advancing a broad transition to regenerative agriculture. The outcomes of this project are limited to potato production in the US, but anyone anywhere in the world can use the same strategy to investigate and heal the soil with a beneficial microbiome.