Pak. J. Bot., 41(5): 2387-2395, 2009. EFFECT OF THE CANOPY COVER ON THE ORGANIC AND INORGANIC CONTENT OF SOIL IN CHOLISTAN DESERT BASIT KARIM 1 , AZAM MUKHTAR 2 , HAMID MUKHTAR 3 AND MAKSHOOF ATHAR 4 1 Department of Chemistry, Islamia University, Bahawalpur, Pakistan, 2 Department of Chemistry, University of Education, Lahore, Pakistan, 3 Institute of Industrial Biotechnology, GC University, Lahore, Pakistan, 4 Institute of Chemistry, University of the Punjab, Lahore, Pakistan. Abstract Present study describes the effect of canopy cover of different shrubs on the physico-chemical parameters of soil. The organic and inorganic content of soil underneath the canopy covers (canopied subhabitat) of four different shrubs viz., Leptadenia pyrotechnica (Khip), Calligonum polygonoides (Phog), Capparis decidua (Karir) and Acacia jacquemeontii (Banwali) were analyzed and compared with the barren soil (uncanopied subhabitat). It was found that the pH of the soil was decreased while moisture content was increased under the canopy covers as compared to barren soil. The mineral content including sodium, potassium, calcium, magnesium, chlorides, sulphates and phosphates was found to be higher under the canopy covers as compared to barren soil. As for as the soil organic matter and total nitrogen content is concerned, it was found that the organic matter was increased from 0.630% in the barren soil to 0.726% under the canopy cover. Similar results were observed in case of nitrogen which increased from 0.040% of barren soil to 0.135% under the canopy. The study suggests that plantation in the desert areas can contribute a great towards fertility of the soil. Introduction Soil is a mixture of organic and inorganic materials. The organic part consists of living things and their remains while the inorganic part is made up of rocks and minerals. The types of plants present in an area have a great impact on the quality of the soil of that area as the plants and soil are strongly influenced by each other (Kim et al., 1995). The characteristics of a soil are undergoing continual changes and the rates of these changes are highly dependant on the type and density of the vegetation (Wasonga et al., 2003). As the roots inhabit chiefly the upper soil layer, and because all materials derived from plant shoots are deposited upon the surface, soils generally show a rapid decrease in organic matter from the surface downwards and away from the canopy cover (Ghuman & Lal, 1983; Noureen et al., 2008). Under certain types of vegetation both the litter and duff are present, but elsewhere the duff and even the litter, may be essentially lacking, at least in certain season. In Pakistan the organic matter content of the soil ranges from 0.69-2.45% (Anon., 2008) in the soils of plains. In the hot dry climates, desert soil is formed which is reddish in color and supports a few grasses and small shrubs resulting in a little humus build up. The plant residue is the most important input to soil which gives rise to the organic and inorganic matter of the soil. So the distribution of these matters in the soil mainly depends upon their origin i.e., the type of the plant and their canopy covers. The organic matter derived from the dead roots of the plants is mainly distributed throughout the soil. On the other hand, the organic matter derived from the dead leaves and shoots is mainly present in the upper horizons of the soil and only under the canopy covers (Spears et al., 2006).