Soil Science

                                            Soil Science

1. SAC - soil chemistry and soil fertility in crop production
2. A-SAC 301 - SOIL FERTILITY , FERTILISERS AND MANURES 2+1
3.B-SAC 301 - SOIL FERTILITY , FERTILISERS AND MANURES 2+1
4. SAC 102 - INTRODUCTION TO AGRICULTURAL CHEMISTRY 2 + 1
5. SAC 101 - Fundamentals of Soil Science
6. SSAC 221 - MANURES , FERTILIZERS AND AGRICULTURAL CHEMICALS
7. SAC - Introduction to Soil Science

Soil Science - Introduction

As civilization moves to beginning of the twenty first century and as World’s
population continues to increase, the importance of a continuing increase in food
production is obvious. India alone is contributing more than a Billion people. It
means that our crop production must be at least doubled by the end of the century.
There are two options open to us. One way is to increase the area under the
plough and the other to increase production per unit area. The scope is limited for
the first option. So greater attention will have to be paid to the increasing of the
production per unit area, per unit time. The strategy is to maintain soil fertility and
proper nutrient management without impairing soil quality (sustainable agriculture).
Soil fertility: Soil fertility is defined as the quality that enables the soil to provide
proper nutrient compounds in proper amounts and in proper balance for the growth
of specified plants. Soil fertility is also defined as the ability of soil to supply
adequately the nutrients normally taken from the soil by plants.
Soil Chemistry: It deals with the chemical constitution of the soil - the chemical
properties and the chemical reactions in soils. It is the study of chemical
composition of soil in relation to crop needs. Traditional soil chemistry focuses on
chemical and biochemical reactions in soils that influence nutrient availability for
plant growth, and potential environmental consequences associated with inorganic
and organic fertilization. Soil chemistry has increasingly focused on the
environment over the past few decades, especially as related to ground and
surface water quality. Understanding the reactions and biogeochemical processes
of potential pollutants and contaminants in soils will enable a more accurate
prediction of fate and toxicity of contaminants, and development of remediation
strategies. The overall goal of soil chemistry/fertility research is a more fundamental
understanding of chemical and biochemical reactions in soils related to plant
growth, sustainability while maintaining soil and environmental quality. Soils are
the medium in which crops grow to provide food and cloth to the world. Soil is the
major factor that limits the type of vegetation and crops. Under similar climatic
conditions, a loose and porous soil that retains little water will support sparse
vegetation when compared to deep, fertile loam or clay. The basic need of crop
production is to maintain soil fertility and soil productivity

Soil as a source of plant nutrients

Soils are complex natural formations on the surface of the earth and consist
of five main components: mineral matter, organic matter, water, air and living
organisms. The rocks and minerals on weathering release nutrients into the soil.
The most important part of the soil with respect to plant nutrition is the colloidal
fraction which consists of inorganic colloids (clay) and organic colloids (humic
substances). Most of soil colloids possess electronegative adsorption sites
available for attracting cations including calcium, magnesium, potassium,
ammonium etc as well as H+ arising from the biological activity. Organic matter on
decomposition releases nutrients. The cations adsorbed on the surface of the
colloids are capable of exchanging rapidly and reversibly with those in soil solution.
The principal immediate source of mineral nutrients to plant roots is ions in the soil
solution. This nutrient supply is gradually depleted by absorption of nutrient ions
by plant roots and continuously replenished by desorption of exchangeable ions on
the clay-humus complex and break down of readily decomposable organic debris.
The microbes in the soil also help in supplementing nutrients by the way of nutrient
transformations. These sources represent the reserves that serve to replace but
only at a relatively slow rate. For intensive cultivation of crop plants, however,
application of mineral salts to soil is required

Reference

TNAU - Tamilnadu Agriculture University, Coimbatore Materials And TNAU - Affiliated Private College Materials, TNAU Government College Materials, ICAR - Indian Council Of Agriculture Research, New Delhi Materials to Collected.