Effect of Gypsum and Sawdust Content on Physical Characteristics of Soil

Abstract

This field experiment was carried out at College of Agriculture / Anbar University / Ramadi in order to evaluate the effect of gypsum content and sawdust on the physical characteristics of soil. Two soils with different content of gypsum were used and mixed in different concentrations to obtain four levels of gypsum, which were 58, 184, 247 and 310 gm kg-1. Sawdust was applied at four concentrations, which were B0 (control), B1 (sawdust extract), B2 (sawdust under 1mm sieve), and B3 (sawdust under 2 mm sieve). Sawdust was mixed in soil depth of 15 cm and applied by 2% of soil weight. The treatments were distributed according to a randomized complete block design (RCBD) with three replications. The sawdust was incubated with the soil for 60 days, and the lost water was added when 50% of the available water was depleted. Then the bulk density, stability of Aggregate, and capillary height were estimated. The results revealed that the bulk density values were in linear increment with the gypsum content, which peaked at 1.61 Mg m-3 for soil with gypsum content 310 gm kg-1, compared to the lowest value 1.33 Mg m-3 for soil with gypsum content 58 gm kg-1. The bulk density decreased by the application of sawdust by giving the lowest values reached 1.20 Mg m-3, under the application of sawdust at B3 to the soil with a gypsum content of 58 gm kg-1, in comparison with the control treatment which recorded 1.33 Mg m-3 . The aggregate stability was decreased with the increment of the gypsum content; as it reached the highest value of 15.20% in soil with gypsum content of 58 gm kg-1 and the lowest value under the gypsum content of 310 gm kg-1 which reached 6.95%. The aggregate stability was increased under the application of sawdust, by giving the highest value reached 19.37%, compared to the lowest value (9.14%) which was recorded under the treatment of sawdust extract. The capillary water height of was 43.2, 38.2, 34.2 and 30.1 cm in soils with gypsum content of 58, 184, 247 and 310 gm kg-1, respectively. The capillary height values were 43.2, 39.6, 37.3 and 34.8 at a time of 22 hours under the application of sawdust in 2 mm of diameter to gypsum contents of 58, 184, 247 and 310 gm kg-1, respectively. Keywords: Sawdust, Gypsum content, Bulk density, Aggregate stability, Water capillary height.