ANDRADE, A. R. S.; http://lattes.cnpq.br/0734786456159447; ANDRADE, Antônio Ricardo Santos de.
Resumen:
The study aimed to characterize physic and hydrically the Embrapa Experimental
Station soils located at the Irrigated Area at Sao Goncalo-PB, Brazil and analyze the
spatial variability of the characteristics. For this, 40 sites were selected and on these
soil samples at depth intervals of 0-30, 30-60 and 60-90cm, were collected. The soil
properties analyzed were the texture, global density, particle density, total porosity,
field capacity, permanent willing point, available water for the plants, soil water
retention curve, infiltration capacity and hydraulic conductivity. The sampling was
systematic obeying a linear criterion, with prc-fixcd distances among points. To
evaluate the spatial variability of the data, statistical methods, based on measures of
position and dispersion, were used.
In general the soil presents a sandy loam texture and therefore high values of global
density. The particle density values are those normally found on sandy loam soils..
Both, the global density and the total porosity suffer the effect of the soil compaction
due to high traffic of agricultural implements. The water contents at the field capacity
and at the wilting point are lows to moderates, founding the higher values at the soil
surface. Each soil depth has a different behavior with respect to water retention, due to
the different physical properties. The soil has a low infiltration capacity, with an initial
infiltration capacity of 10.5 cmh'1 decreasing to a constant value of 1,21 cmh"1 ,
denominated basic infiltration.. The Kostiakov Model was more adequate to estimate
the water infiltration, than the I lorton Model. The saturated hydraulic conductivity
values found show a soil with a moderately low drainage.
The results show a great vertical and horizontal spatial variability of the analyzed
properties. With exception of the particle density, the properties showed different
degrees of variation with accentuated standard errors, amplitudes and variation
coefficients. Of the studied properties, the hydraulic conductivity was the one that
showed the higher variability Also it was the only property whose frequency
distribution did not have a normal distribution. Due to the great vertical variability,
sampling requirements increased with depth.