EFFECTS OF ROCK FRAGMENT ARCHITECTURE ON SOME SELECTED SOIL PROPERTIES IN A SEMIARID ENVIRONMENT
Stony soils cover a large portion of the Iraqi territory, particularly, the hilly and mountainous areas of Iraqi Kurdistan Region. Albeit they are abundant, their properties are not well recognized. Accordingly, minilysimeter and repacked plot experiments were conducted under open air at Sumail site-Duhok governorate –Kurdistan regions. The main objectives were to study the architectural effect of rock fragments size, content and cover on topsoil water conservation, surface soil temperature and infiltration rate. In each experiment the study factors were two types of soil, different soil rock content/cover and different rock fragment size. The results of the minilysimeter experiment signified that with a few exceptions, the retained soil water content over time under a rock cover of 40% was superior to those under control and under a rock cover of 20% for the same rock size. There are also indications that the effectiveness of rock cover in controlling evaporation decreases with an increase in rock size. The soil temperature under rock mulching was lower than that of the control by 0.5 to about 2.5 oC depending on the treatment combination. The results of the repacked plots also revealed that the infiltration rate increased with increasing rock content up to 30% and began to decline beyond this level. The 2–4.75 mm rock fragment treatment offered the highest average or basic infiltration rate compared with the other sizes under the same level of soil rock fragment content.
Stony Soils, Rock Fragments, Topsoil Water Conservation, Infiltration Rate