Indian Agricultural: Growth, Generation, Policy & Problem Indian Agricultural | Page 17

Pg.no. 16
Water potential: Water potential describes the tendency of the water to flow from one area of the soil
to another. While water delivered to the soil surface normally flows downward due to gravity, at some
point it meets increased pressure which causes a reverse upward flow. This effect is known as water
suction.
Horizonation: Typically found in advanced and mature soils, horizonation refers to the creation of soil
layers with differing characteristics. It affects almost all soil variables.
Fertility: A fertile soil is one rich in nutrients and organic matter. Modern agricultural methods have
rendered much of the arable land infertile. In such cases, soil can no longer support on its own plants
with high nutritional demand and thus needs an external source of nutrients. However, there are
cases where human activity is thought to be responsible for transforming rather normal soils into
super-fertile ones.
Biota and soil biota: Organisms interact with the soil and contribute to its quality in innumerable ways.
Sometimes the nature of interaction may be unclear, yet a rule is becoming evident: The amount and
diversity of the biota is "proportional" to the quality of the soil. Clades of interest include bacteria,
fungi, nematodes, annelids and arthropods.
Soil acidity or soil pH and cation-exchange capacity: Root cells act as hydrogen pumps and the
surrounding concentration of hydrogen ions affects their ability to absorb nutrients. pH is a measure of
this concentration. Each plant species achieves maximum growth in a particular pH range, yet the
vast majority of edible plants can grow in soil pH between 5.0 and 7.5.
Ramesh Kumar P