Pakistan can be categorized under dry land country. Several types of land areas include 80%, of arid or semiarid land, 12% dry and sub-humid land while left over is 8% which is humid. High evapotranspiration in semi-arid and arid regions is the key cause of the salt accumulation in the soil. Generally, salt free soils have electrical conductivity less than 4 dSm-1 in which all types of crops can be cultivated. On the other hand, the land deprivation and desertification problems are due to unmaintainable land management practices and growing stresses on natural resources as in the lands of other emerging nations.
In Pakistan certain extortions of land degradation are bigger than others in terms of their appearance, 14 mha of land, which have been inducted to traditional irrigation practices is resulted in water logging and salinity, 11 mha of land is affected by deforestation whereas 24 mha of land is affected by overgrazing.
Effects of Salt affected soils
Salinity has negative effect on the production of agriculture land. In salt affected soils plant growth is distressed in many ways; they would be facing poor water and air permeability owing to soil dispersion, low water availability due to poor air conductance, hindrance for seedling emergence down to hard crust on soil surface, low activity of useful microbes due to high soil pH and SAR, hard CaCO3 layer might hinder root growth, decreased solubility and thus availability of micro-nutrients like Zn, Cu, Fe, Mn etc and continuous loss of top fertile soil during rain due to low water infiltration. Salinity and sodicity also decreases 25% production of major crops and water logging decreases the yields of cotton up-to 2%, 9% for sugarcane and for wheat decrease in production is up to 21%.
Land Reclamation Practices
For reclaiming the salt affected soils, there are some suggestions through which the farming community can make their soils more valuable and can enhance their crop production.
Reclamation through organic or inorganic material
- Reclamation of soil can be done by applying 100% gypsum on moderately saline-sodic soils of medium texture.
- The application of sulphur and sulphuric acid can also effectively used to reclaim the soils having high Exchangeable Sodium Percentage (ESP), Sodium Adsorption Ratio (SAR) and pH.
- The application of Farm Yard Manure (FMY) strongly recommended reclaiming the calcareous salt affected soils.
- For land reclamation press mud is also recommended, which is inexpensive alternate to gypsum treatment but it takes years.
Reclamation through cultural and physical practices
- Rice-barseem cropping pattern can be used for reclamation of land.
- In salt affected lands leguminous crops can also be grown to improve the fertility and physical condition of soil.
- Cultivation of sesbania, barseem and cluster beans are suggested for green manuring, during reclamation practices.
- Moderately salt affected, well-drained and medium textured soils can also be reclaimed by using cotton-wheat cropping pattern.
- Soil texture can be improved by applying deep ploughing, increasing seed rate and sowing of crops on ridges.
- In saline land, bed and furrow technique recommended for sowing the crops.
Biological reclamation of saline-sodic soils
- To decrease the salinity and sodicity of soil, rice husk is suggested by experts.
- Kallar grass, maize, sorghum and economical biological reclaiment can be used to reclaim the calcareous saline-sodic soils.
- For reclaiming the saline soils continuous cropping for long period of time is recommended.
- Biologically rice-barseem cropping pattern can be effectively used to minimize the effect of highly saline-sodic soils while the alternates are sesbania and kallar grass.
- Jantar and barseem may also be grown to reclaim the fine textured soils, under deep ploughing.
- The soils having slight or low sodicity problem are recommended to reclaim through biological reclamation practices as compared to other chemical amendments.Authors:
- M. Waseem Aslam Ghouri 1st
- Muqaddas Tariq 2nd