2. Materials and methods
Soil evaporation was measured or estimated with different inorganic and organic mulching materials in laboratory (experiment 1) and field (experiments 2) conditions. In experiment 1, the top layer (0–10 cm) of a clayey soil located in the experimental farm of the Agrifood Research and Technology Center of Aragon (CITA) was used. The soil of experiment 2, located in the AFFRUCAS (Association of fruit growers of the County of Caspe) farm, has an average depth of 1.5 m and is classified as calcic haploxerept, fine loamy, mixed, thermic (Soil Survey Staff, 2006).
The field capacity (FC) and permanent wilting point (PWP) determinations were performed in the CITA laboratory with a pressure plate apparatus at pressures of 33 and 1500 kPa, respectively, according to Klute (1986). Disturbed soil samples were taken at several locations in each experiment with a 50 mm diameter auger. The particle size composition and the values of FC and PWP of the soils used in the two experiments are presented in Table 1 (means of three replications).