The soil under our feet in a flourishing garden or a fertile farm is a living and thriving ecosystem. It contains a huge diversity of fungi, bacteria, protozoa, nematodes, anthropoids, earthworms and other living organisms. The living soils a healthy soil as it has the potential to nurture and sustain plants and animals. The living soil has been as provider to the mankind and has been fulfilling all its need from time eternal.
A living soil play a very crucial role in absorbing rainwater as a sponge which not only prevents run offs of the rain water but absorbs, release and transforms many different chemical compounds. The organic matter of the living soil stores a huge amount of atmospheric carbon, thus helping with control of global warming.
The soil consists of four parts, solid mineral particles, water, air and organic matter. The particles are generally of sand, silt and clay size, derived from weathering of rocks or deposition of sediments mainly consisting silicon, oxygen, aluminium, potassium, calcium, magnesium, phosphorous and other minor chemical elements. These chemical minerals are available in the crystalline particles which have pore spaces in between them that allow them to hold water through capillary action. This process allows water, with the help of atmospheric carbon dioxide, to slowly dissolve the mineral particles and release nutrients (this process is called chemical weathering). The soil water and dissolved nutrients, together, referred tons the soil solution, are now available for plants.
The animals eat these plants and extract nutrients and energy for themselves and then defecate what remains. The soil organisms help to incorporate both plants and manure residue into the soil along with the toots that die. This dead plant material and manure become a feast for a wide variety of organisms like beetles, spiders, worms, fungi, bacteria etc. At the same time, the decomposition of organic material makes nutrient available again to plants, completing the cycle.
In agriculture, soil health becomes a question of how good the soil is at supporting the growth of high-yielding, high-quality and healthy crops. The characteristics can be listed as below mentioned attributes of healthy soil:
The soil should have a sufficient supply of nutrients throughout the growing season. It contains soil organic matter that improves the structure of the soil which enables soil to retain more moisture. The pH value is in the range 6.0-6.8. It has a good drainage quality. It consists of variety of micro organisms the support the plant growth.
The soil should have gooth tilth to facilitate plant roots development with least amount of effort. A soil with good tilth is more spongy and less compact. As soil with a favourable and stable soil structure also promote rain water infiltration and water storage for plants to use later.
For good root growth and draining, a soil with sufficient depth before a compact soil layer or bed rock is reached is required. Deeper soils generally can provide more water and nutrients to the plants than shallow soils. Soil depth can influence ware availability. Soil depth is also important as it helps the roots interact with its micro organisms.
D. Drainage and Aeration
A good soil should have a good drainage so that it dries enough and during the rains it permits timely field operations. Also, it is essential that oxygen is able to enter the root zone and just as important that carbon dioxide leaves it. The good drainage provided a better environment for plant growth as it removes the excess water which impedes the root respiration. It increases the microbial decomposition as the presence of air is essential for the growth of micro organisms which converts the soil organic matter to manure. It improves the soil structure and the soil infiltration capacity due to which soil erosion is reduced. The drainage of sil maintains proper soil temperature by removing the excess water which allows the soil to warm up quickly.
E. Minimal Pests
A soil should have low population of plant disease and parasite organisms. Also, there should be low weed pressure, especially aggressive and hard to control weeds. Healthy soils have adequate, but not excessive nutrients. Excessive nitrogen can make plants more attractive or susceptible to insects and overabundant nitrogen and phosphorous can pollute surface and ground water. Healthier soils also harbour more diverse and active populations of the soil organisms that compete with, antagonise and ultimately curb soil based pests.
F. Free of Toxins
The good soil is always free of chemicals that might harm the plant. here can occur naturally, such as soluble aluminium in very acid soils or excess salts and sodium in arid soils. Potential harmful chemicals also are introduced by human activity, such as fuel oil spills or when sewage sludge with high concentration of toxic elements is applied . In toxic soils, plant can uptake potentially toxic elements which are water-soluble or get easily solubilised by roots. As potential toxic elements cannot be degraded, when their concentration within the plant exceed permissible limit. They adversely affect the plant directly and indirectly. The uptake of potentially toxic element from contaminated soils by plants comprises a major path for these elements to enter the human and animal food chain, which is harmful to them.
It is the ability of soil to resist or recover their health state in response to destabilising influences and the health of the living/biological components of the soil is crucial for soil resiliency. Soil health is tightly coupled with the concept of soil quality and the terms are frequently used interchangeably. A resilient soil should be able to:
- Sustain biological activity, diversity and productivity.
- regulation and partitioning water and solute flow.
- filter, buffer, degrade, immobilise and detoxify organic and inorganic materials.
- store and cycle nutrients and the elements within Earth’s biosphere.
- provide support of socioeconomic structures and protect archaeological treasures associated with human habitation.