Soil is the upper layer of the earth’s crust, which sustains life. It consists of a mixture of mineral particles, organic material, organisms, and liquids, and has various physical, chemical, biological and morphological properties. It sustains plant life, which in turns sustains the lives of animals and humans on the planet. Since we rely on soil to supply food, feed, and fibre to the world it is an essential resource. Furthermore, it is not merely a substrate for the growth and proliferation of plants, it also maintains environmental quality through services like the decontamination of water, it sustains biodiversity, maintains ecosystems, and serves as a carbon sink.
Despite its significance to the survival of life, soil is constantly degraded, mainly through agricultural processes. More than 50% of agricultural soils are moderately to highly degraded. Soil degradation is the result of erosion, pollution, extensive cultivation, over-grazing, and land clearing. Moreover, the growing human population increases the demand for feed, fibre and food and puts immense pressure on all natural resources, including soil.
What are soil health and soil quality?
The term “soil health” is associated with the fitness of the soil to function as a system that can sustain biological productivity, environmental quality and animal and plant health. Soil health considers the soil as a living system, which delivers services. Mostly the function in this system is carried out by a myriad of living organisms that require management and conservation. Healthy soils are synonymous with sustainability whereas life cannot thrive in unhealthy soil. Soil health is, therefore, a major contributor to agricultural productivity and sustainability and indirectly affects human, animal, and plant health. Soil health varies according to the soil characteristics and properties and currently, mainly due to the complex nature of the soil, there is no consensus on what the exact requirement for healthy soil is.
Soil quality refers to the inherent properties of soil including chemical and physical properties which are intertwined with regional ecosystems and climate. Practises like mechanical soil cultivation and repeated production of crops on the same soil over many years can cause physical loss of soil through soil erosion. These farming methods also cause loss of organic matter in the soil and the release of CO2 into the atmosphere. The conservation and maintenance of soil quality are non-negotiable in the quest for sustainable plant production systems, yet it can be a major challenge to develop agricultural systems that sustain high levels of plant production while conserving the land.
Soil health and quality assessments
Soil health and quality varies over environments, climates and land use management types and may be measured in several ways. Soil organisms are surrogates for soil health and quality because the abundance, diversity and functions of these organisms strongly correlate with the health and quality status of the soil. As the environment and soil properties change, so do the soil biology. These biological measures link directly with the abiotic environment in which the organisms live.
Soil organisms respond to anthropogenic disruption and are indicators of soil ecosystem services. They live in soil respond sensitively to the climate and land management practices. These ecosystems services include contributions to water holding capacity, decomposition of organic materials, recycling of nutrients, detoxifying toxins and promoting plant health by suppressing pathogenic organisms.
Additionally, the organisms that live in soil, also reflect the properties of the soil and their abundance, diversity, community stability and food web structure are indicators of the status of the soil. As a surrogate for soil health and quality, organisms that live in soil are relatively inexpensive and easy to measure. For example, earthworms have for many years been used as a measurement of soil health, but the diversity and abundance of nematodes, mites, bacteria, and fungi also provide information on soil health, quality, and functions. Thus, measurement of soil organisms is sensitive to disturbance and are correlated with soil function and a reliable indicator of soil health and quality – although the measurement of soil organisms must follow well-developed sampling protocols and relevant soil organism’s identification processes.
These organisms reflect land management decisions and ultimately the productivity and health of the plants and animals living off that soil. Indicators of soil health should be easy to understand to those who manage the land and are stewards of soil quality and health.
Assessments of soil health and quality are essential to sustainably manage land. These assessments help to identify problems in production areas and help farmers and other land managers to link science and practice when assessing the sustainability of their soils. Generally, soil health and quality indicators should assess both the biological and physiochemical (or abiotic) factors that contribute to high quality and healthy soils.The full article is for subscribed members only. To view the full article please subscribe. It’s FREE!Log In Register
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