Influence of different organic materials on physical properties of desert and cultivated soils

Thefield and pot experiments were conducted in Belarus and Egypt to study the effect of different natural organic materials on physical properties of sandy and sandy loam soils. The following materials were studied: well known and widely distri- buted peat moos (PM), new Belarussian peat-sapropel ameliorant (PSA), ammonium humate (AH) and fulvic acid (FA). The obtained results have shown that addition of studied organic materials decreased electrical conductivity (EC) and soluble cations and anions content in the soils, apart from soluble K which was increased on PSA variant. The highest increase in total soil aggre- gates was observed with PSA. Data of total soil porosity and pore size distribution confirmed again the superiority of PSA for improving soil properties. In spite of the small percentage value (0.1 and 0.5%), in contrast to the relatively high rates of PSA and PM (3 and 5%), AH showed a pronounced role in increasing total porosity and available water. Data of surface tension of soil solution showed a range of decrease from about 75 to 17% after treatments, reflecting improve- ment of soil wettability and capillary rise. It was concluded that the best effect of PSA on soil properties is due to the presence of the organic-mineral and mineral compo- nents of sapropel. On the other hand, the effective role of the small amount of AH (0.5%) in increasing soil aggregation, available water, and plant growth, confirm that the effect of the other organic materials is basically due to humic acids.