International year of the soils

Nongmaithem Leindah Devi *

SOILS SUSTAIN LIFE

Consider the world and all the things that make the earth a great place to live. It may come as a surprise that all living things depend on 4 basic things. We might first think of food, clothing, shelter and water. With a little more thought; air. Looking at the bigger picture, energy is seen as critical, with sunlight as the ultimate source of energy. Upon further consideration the first three items – food, fiber, and shelter – are all related to a single often overlooked item: Soil. Soil is one of the four things we cannot live without.

Soil, Water, Air and Sunlight are needed for all life as we know it. Soils cover the upper crust of the earth. Soils are complex mixtures of minerals, water, air, organic matter, and countless organisms that are the decaying remains of once-living things. It forms at the surface of land – it is the "skin of the earth." Soil is capable of supporting plant life and is vital to life on earth.

Soil, as formally defined in the Soil Science Terms, is:

1. The unconsolidated mineral or organic material on the immediate surface of the earth that serves as a natural medium for the growth of land plants.

2. The unconsolidated mineral or organic matter on the surface of the earth that has been subjected to and shows effects of genetic and environmental factors of climate (including water and temperature effects), and macro and microorganisms, conditioned by relief, acting on parent material over a period of time.

So then, what is dirt? Dirt is what gets on our clothes or under our fingernails. It is soil that is out of place in our world – whether tracked inside by shoes or on our clothes. Dirt is also soil that has lost the characteristics that give it the ability to support life – it is "dead."

Soil performs many critical functions in almost any ecosystem (whether a farm, forest, prairie, marsh, or suburban watershed).

There are seven general roles that soils play:
1. Soils serve as media for growth of all kinds of plants.
2. Soils modify the atmosphere by emitting and absorbing gases (carbon dioxide, methane, water vapor).
3. Soils provide habitat for animals that live in the soil (such as groundhogs and mice) to organisms (such as bacteria and fungi), that account for most of the living things on earth.
4. Soils absorb, hold, release, alter and purify most of the water in terrestrial systems.
5. Soils process recycled nutrients, including carbon, so that living things can use them over and over again.
6. Soils serve as engineering media for construction of foundations, roadbeds, dams, buildings and preserve or destroy artifacts of human endeavors.
7. Soils act as a living filter to clean water before it moves into an aquifer.

SOILS SUPPORT URBAN LIFE

We understand that soil is a dynamic natural body that made up of solids, liquid and gases and occurs on the earth's surface, contains living matter and supports or is capable of supporting plants. But, soil is actually much more than this describes. Civilizations have either flourished or perished partly based on this natural resource and the capability of its people to manage and use it wisely.

We all depend on the soil, regardless of whether we live on a farm, or in the areas of our greatest populations, our nation's urban areas. The urban areas were once farms or open spaces with the capacity to produce food and fiber, or perhaps support an abundance of wildlife. Many people view urban areas as concrete jungles with much of the soil's redeeming values lost under layers of concrete and asphalt.

The "urban" reuse of the land in fact requires many uses, all of which depends on the soil. Not only does the soil support urban life, it is also the critical element supportive of the urban lifestyle. Soils in urban areas are often much different than farmland soils used to grow food or rangeland soils used to support essential ecology.

Urban soils develop from soil material that has been disturbed, manipulated and transferred by various living creatures. Usually, urban soils are poor in physical, chemical and biological properties, but this doesn't mean that urban soils should be regarded as disfunctional. Urban soils play a vital role in the livelihood of cities, biomass production, flood prevention, groundwater recharge, carbon sequestration, as well as cooling and humidification.

We should consider, especially during urban planning, urban soil as an important component in the planning process. In urban areas, due to lack of space for cultivation, vertical gardens are becoming more and more popular. There is a growing trend to revitalize vacant property in urban areas and convert it to green infrastructure or urban agricultural areas.

Urban agriculture plays a key role in two global challenges: urbanization and food security. It can provide important contributions to sustainable, resilient urban development and to the creation and maintenance of multifunctional urban landscapes. Many challenges exist when trying to grow food in urban soils, these might include soil compaction that causes poor drainage and the presence of unwanted materials, such as debris from glass, plastic and other garbage.

Urban soils also face interrupted nutrient cycling and interrupted or modified microbial activities. It may contain low levels of nutrients and contaminants such as lead, arsenic, cadmium and polycyclic aromatic hydrocarbons. The urban gardeners need to make sure to follow common practices like soil nutrient levels are appropriate and make sure to do things to enhance soil quality, such as get their soil tested for the common contaminants. To enhance soil productivity for all of these plants, composting as a way to incorporate organic material back into the soil.

SOILS SUPPORT AGRICULTURE

The soil is the ultimate source of the nutrients that our bodies need. The vitamins and minerals that are a necessary part of our diet come from plants that have, in turn, gotten those same vitamins and minerals from the soil. Soils support agriculture by serving as the foundation of where we grow food.

With the world population expected to surpass 9 billion people by 2050, a main challenge for those involved in agricultural production is using the same limited resources, including soil, to increase production and meet food demands. From field crops to garden vegetables, various types of foods rely on soil for growth. The world population continues to grow and one of the main challenges those involved in agriculture face is increasing the overall productivity of soils to meet elevated food demands.

Soils are an important source of nutrients for all crops. Different nutrients; nitrogen, phosphorus, potassium, zinc and sulfur are the most common essential nutrients for plant growth. The nutrient concentration in soils can be replenished in a number of ways. There are a lot of natural processes that occur that provide nutrients for crops through the soil.

For example, free-living organisms and legumes grown in the field can produce nitrogen for crops. In addition to enhancing soil nutrients naturally, farmers can also apply nutrients in other forms, including using fertilizers, animal manure and waste products from cities and industries. Enhancing the soil nutrients naturally can be done through crop rotation.

Different crops use different amounts of water and nutrients, which can affect the soil balance. Producers use crop rotation as one key tool, as well use cover crops, to help with the cycling of nutrients in the soil. With the use of cover crops, which are crops planted specifically for erosion management and to enhance soil fertility, soil quality and water infiltration, farmers strive to increase soil and environmental health.

Cover crops can add nutrients to the soil both at the surface and below the surface through their valuable root systems. Another important function of soils is to store water that plants need for growth. Farmers can help the soil accept and store water in many ways, including conservation tillage, which is used to keep the surface of the soil covered with crop residues to enhance the infiltration of water and reduce runoff.

This helps maintain residue on the soil surface and capture more water. Another alternative to no-till is a minimum tillage system, sometimes called strip-till, where farmers only disturb a small amount of soil to place the seeds, nutrients and fertilizer. A strip-till system, although it does disturb the soil to some degree, can provide a balance between a good seedbed and soil protection with residue cover.