Soil Study

Tree Planting in Problem Soils The ultimate aim of this exercise is to think of some appropriate measures and treatments that would minimum the effects of prevailing harmful factors and therefore maximum plant survival and enhance their growth rate. A normal form area develops into a problem area when shortage or excess of any or some environmental factors prohibit plant establishment and severely retard their growth. Such factors vary from one locality to another and can be any one of the numerous environmental (climatic, edaphic or bio tic) factors or their combination.

Hard Clayey Soils These are the soils in which clay particles constitute over 35% or more of the total weight.  These soils are extensively distributed in salt range foot hills of Punjab and western Kohistan of Sindh.  The plants that grow in these soils have to face the following problems. Soil is compact. There is lack of aeration and drainage. Root penetration and respiration is restricted. Soil is usually shallow due to presence of Ca pan in the lower horizons. This leads to reduced water storage in the thin surface layer of the soil which is exhausted very soon. Because of high adsorptive power of clay, even a slight but continuous addition of Na is enough to cause deflocculation which is very harmful phenomenon for plants. Some kind of help will have to be provided during establishment of vegetation and initial growth stages. Once establishment and having gained complete control of site, the vegetation will by itself bring rapid improvements in s...

Waterlogged Soils These are the soils where water-table rises high and reaches within 3 feet of ground surface most of the time and thus affects crop roots. In extreme cases, the water-table rises even higher than ground surface. Waterlogging is very extensive problem in irrigated areas. It is caused by addition of huge amount of percolation and seepage water from canals, distributaries and water channels as well as inefficient irrigation practices and absence of any effective drainage system. The intensity of water logging is variable and depends on season, general land slope and soil porosity etc. Presence of gravitational water in the root zone for a long period of time excludes the soil air. Plant roots are therefore, unable to respire properly. Oxygen dissolved in soil water gets exhausted very soon because there is no new addition of oxygen to the standing water. In some cases, the ground water may pick up excessive amount of carbon dioxide and salts and intensif...

Wind Eroded Soils In arid sandy areas such as deserts and sea coast, strong wind bellow frequently and cause soil erosion as well as flagging of tree crowns. This is very acute problem in Thal, Cholistan, Tharparker and deserts of Balochistan. The plants that grow in such situation have to face some or all of the following problems. Since the soil is unstable, therefore; the plants are continuously faced with either exposure of their root system due to blowing away of sand or burial of their shoots due to deposition of new sand. Moving sand particles cause mechanical damage to tender shoots and foliage. The transpiratory load is extremely high. Light intensity tends to be very high due to its reflection from shining sandy surface. Water holding capacity of sandy soil is very low which leads to water deficiency for most of the time. The problem of soil erosion by wind can be successfully tackled by considering the following points: A species shou...

Salt affected Soils These soils are those in which either the salt contents of lower horizons concentrate in or on the soil surface or normal proportion of various cations and anions present in soil is disturbed in a big way by excess or shortage of certain ions. This redistribution of salts of salts in soil profile is generally caused by the rising of water table accompanied by intensive evaporation from the surface. The saline water moves up through capillaries and evaporates into the atmosphere while leaving the salts on the soil surface. These salts are frequently seen in the form of thin white crust in the saline area. This crust is quite conspicuous during winter. It has been estimated that about 1/4 to 1/3 of our irrigated area has gone out of production because of salinity. Product vising these areas by tree planting is a major breakthrough. Salinity of soils is rightly considered as enemy number one of World’s Agriculture. In Pakistan about 16.75 million acres area ...