Abstract:
The amount of moisture stored in the soil and
available to the crop can be inferred from
determinations of soil texture, structure and porosity, or
measured directly by pF curve determinations. When
water is added to the soil by rain or irrigation, the soil
surface becomes saturated, and the water travels
downwards under gravity and capillarity, i.e. drainage
takes place. The amount of moisture stored in the soil
and available for plants can be measured directly by pF
curve determinations. An argic horizon is a subsurface
horizon with distinctly higher clay content than the
overlying horizon. The Romanian Soil Taxonomy
System (SRTS - 2012) contains soil types with B argic
horizons, as follows: Preluvosol, Luvosol, Planosol,
Alosol, and Stagnosol. For low suction values, samples
are placed on a porous plate, saturated with water.
Suction is applied by lowering the water level in the
manometer. For high suction values, samples are
equilibrated in pressure plate extractors. For practical
use it is necessary to know the amount of water which
can be depleted before these suctions are reached. On
the base of data, presented were calculated the curve
suction – moisture content for a Stagnic – albic Luvisols
from Lalasint. The suction – moisture curves allow to
establish the irrigation requirement, leaching
requirement, deep loosening requirement, the moisture
reserve.
