Soil Salinity and Drought and Its Effects on Agriculture or Biodiversity - Term Paper Example

Soil salinity and/or drought and its effects on agriculture/biodiversity (Name) (Institution) (Course) (Instructor) (Date of submission) Introduction Agriculture and biodiversity are two key interrelated components that are the main source of sustenance for every species of plants and animals. Biodiversity is the basis of ecosystem services vital for sustaining agriculture and the overall wellbeing of human beings (Magdoff& Van Es, 2009). Quality agriculture is dependent on biodiversity while agriculture adds to conservation and sustainable utilization of biodiversity. This means that agriculture enhances and is improved by biodiversity. An essential element that links biodiversity with agriculture is soil. Soil form the basis for sustainable farming since it is essential for the healthy growth of crops, which ensures proper nutrition for people and animals (Munns, 2012). According to Magdoff and Van Es (2009), healthy soils are able to sustain growth of plants and crops while sustaining the quality of the environment. According to Wallender and Tanji (2011), healthy soils are characterized by proper balance of the chemical, physical and biological properties of the soil. Be it as it may, there are instances when the chemical properties of soil out-power the physical and biological properties, which makes the soil unhealthy. Among these instances is soil salinity. This report seeks to describe the nature of soil salinity and its impact on human life, plants, ecosystems and environmental cycles. The nature of Soil Salinity Soil salinity entails the occurrence of soluble salts in the soil as described by (Munns, 2002). According to Qadir, (2010), soluble salts found in water and soils that causes salinity are varied and includes calcium, sodium chloride (also known as table salt), magnesium, potassium, sulphates, carbonates and bi carbonates. The above mentioned salts come from weathering rock matter, wind and rain depositing oceanic salt on land and from marine sediments. There are two forms of salinity which includes primary salinity, which is salinity that occurs naturally such as salt lakes and secondary salinity which is salinity induced by human activities such as over-irrigating land (ANRA, 2009). Soil salinity occurs in two forms namely irrigation salinity and dryland salinity. According to Rengasamy (2002), dryland salinity is a challenge affecting substantial land mass globally, with countries such as Australia having more than two million of its hectares being impacted by dry land salinity and more than 150,000 hectares affected by irrigation salinity. Based on reports filed by FAO Land and Plant Nutrition Management Service as indicated by Munns (2012), more than 6%, which accounts for more than four hundred million hectares of the land globally is impacted by salinity. The landscape under cultivation globally is affected by salts. 19.5% which represents 45 million of hectares of the 230 million hectares which are under irrigation are affected by irrigation salinity (Munns, 2012). In addition, 2.1% which is equivalent of 32 million hectares of the 1500 million hectares of dry land which is under cultivation are affected by dry land salinity. Table 1 shows the global distribution of soil salinity in million hectares. Areas Total area in million hectares Saline soils in million hectares Saline soils in percentage (%) Asia, Australia and the Pacific 3107 195 6.3 Near East 1802 92 5.1 Latin America 2039 61 3.0 Africa 1899 39 2.0 Europe 2011 7 0.3 North America 1924 5 0.2 Table 1: global distribution of soil salinity as indicated by (FAO Land and Plant Nutrition Management Service-(Munns, 2012) Soil Salinity in Australia The main form of soil salinity in Australia is dry land salinity (ABS). Dry land salinity occurs when there is substantial amount of water that seeps into the ground water system compared to the amount of water which is discharged from the ground water system that results in rising of the water table (ANRA, 2009). During the rise of the water table, the water underground dissolves any soluble salts in the subsoil and as plants draws in water and through evaporation, the dissolved salts are discharged or concentrated in the topsoil causing dry land salinity (Munns, 2012). The author continues to that, the clearance of perennial native plant cover and the continued planting of annual crops that are shallow rooted has been linked with dry land salinity since the latter, utilize less water leading in more ground water being recharged and the water table rising. Dry land salinity has been a modern challenge and an obstacle to sustainable agriculture and biodiversity owing to the negative implications it generate to people, plants, and animals and to the overall environment (Wallender&Tanji, 2011). Other than causing deterioration in productivity in agriculture, dry land salinity hinders uptake of water and important nutrients by plants, and it generates salts that are toxic to ground cover, causing degrading of remnant ground cover, which translates to loss of biodiversity as echoed by (ABS). In addition, when water supply points such as aquifers contains saline water, water for human, industrial and agricultural use are greatly compromised leading to lost productivity economically (Munns, 2002). In Australia, there are vast lands of agriculture lands that are in regions at increased risks of dryland salinity. Based on reports by Australian Natural Resources Atlas (ANRA), other than agricultural land which is at risk, there are other assets in Australia that are prone to risks of dry land salinity as a result of rising water tables which includes remnant and planted perennial vegetation, length of streams and lakes, rail, roads, towns and fundamental wetlands such as Ramsar Wetlands (ANRA, 2009). According to ANRA, the areas with the most impact of dry land salinity are those in Temperate Semi-Arid slopes, crop-pastures zones in New South Wales, Victoria, South Australia, irrigation regions of Murray-Darling Basin and plains across agro-ecological areas that include wheat-sheep belt located in south west Western Australia (ANRA, 2009). Table 2 shows the regions across Australia at greater risks of dry land salinity from the year 2000 and by the year 2050. State YEAR 2000 YEAR 2020 YEAR 2050 New South Wales 180 600 580 000 1 300 000 Victoria 665 500 1 306 000 3 110 000 Queensland not assessed not assessed 2 600 000 South Australia 326 000 421 000 521 000 Western Australia 3,553,000 4 182 000 6 490 000 Tasmania 53 000 70 000 90 000 Table 2: Australian states under greater threat of dry land salinity from year 2000 and by year 2050 as reported by ANRA The impact of soil salinity on human life, plants, ecosystems and environmental cycles In Australia and other parts of the world, the major implications of dry land salinity are the salinization of fresh water points such as rivers, which negatively influences the supply and use of water for consumption and irrigation purposes as echoed by Chhabra, (1996). The outcomes of these effects are severe economic, social and ecological challenges not only in the rural areas but also for communities in urban areas (Qadir, 2010). For instances, water supply points in Western Australia are already too saline for use in domestic purposes, which signify trouble for future fresh water supply. Continued concentration of salts has the potential to alter the habitats of plants in wetlands and tributaries, which leads to negative effects on marine life and the overall aquatic life within these areas (Wallender&Tanji, 2011). The ecological, social and economic costs linked with soil salinity are significant and the negative implications heavily influence agriculture and biodiversity. In regards to agriculture, soil salinity either in the form of dry land or irrigation salinity inhibits the healthy growth and lifecycles of crops and biological processes such as decaying of organic matter respectively (Munns, 2002). Qadir (2010) indicates that soil salinity causes land degradation which inhibits sustainable agriculture which enhances and is improved by biodiversity. Other than causing decline in agricultural production, soil salinity lead to significant loss and reduction of quality water for use domestically and commercially (Chhabra, 1996). In addition, damage to developmental infrastructures such as rail, roads and piping systems owing to metal corrosion and bitumen breakdown which causes pot holes and cracks respectively and more significantly, it causes deterioration and damage to biodiversity in all ecosystems in water and on land (Ghassemi, et al., 1995).In relation to the reducing suitability of water for human, irrigation and animal use, the incurred costs include rising costs of treating waters and the economic costs of repairing failing infrastructures such as corroded piping systems, water channels and rail systems(Wallender &Tanji, 2011). The effect of soil salinity on Australian Agriculture has varied impacts among them partial or complete loss of land productivity (Munns, 2012). Since majority of plants and ground cover are not tolerant to salts and more often than not, they are unable to draw in water from the soils with high salt concentrates that means they eventually weather and die if exposed to salinity. Soil salinity destroys the structure of soil and it deposits toxic elements on top soil which hinders growth of plants and minimizes ground cover, which results in land clearing, which facilitates soil erosion (ANRA, 2009).The extensive appearance of bare land on previously green areas causes loss of amenity and aesthetic of landscapes in areas such as sports arenas, recreational parks and gardens. The rise of water tables results in dysfunction of septic tanks which generates additional ecological and health risks and challenges (Chhabra, 1996). Overall, the lack of adequate ground cover due to land clearing caused by dry land salinity and irrigation salinity negatively impact on bio-organisms and bio processes, which in turn damages the life cycles of various plant and animal species that reverberate to destruction of terrestrial and aquatic eco systems as supported by Ghassemi, et al., (1995). Conclusion The impact of soil salinity on the wellbeing of people, animals and the life on earth is enormous. Soil salinity entails the occurrence of soluble salts in the soil. Soil salinity is a global challenge that requires global attention and focuses in order to effectively and efficiently manages it. As identified in the report, soil salinity which can either be dry land or irrigation salinity negatively affect agriculture and biodiversity due to land clearing, salinization of fresh water supplies and toxicity to plants. Major states in Australia are at enhanced risks of soil and water salinity, which signify a greater risk to the overall productivity of Australia as a developed economy. References ABS. Year Book, Australia. Canberra: Australian Bureau of Statistics. Australian Natural Resources Atlas (ANRA), 2009, Salinity – Impacts. ANRA. Accessed on 8th Sept 2012 from Chhabra, R 1996, Soil Salinity and Water Quality. New Jersey: Taylor & Francis. Ghassemi F, Jakeman A.J., & Nix H.A 1995, Salinisation of land and water resources: Human causes, extent, management and case studies, Sydney, UNSW Press. Magdoff, F. & Van Es, H 2009, Building soils for better crops. London: Sustainable Agriculture Research and Education (SARE) publication. Munns, R. 2012, The impact of Salinity Stress.Canberra ACT:CSIRO Division of Plant Industry. Accessed on 8th Sept 2012 from http://www.plantstress.com/articles/salinity_i/salinity_i.htm Munns, R., Husain, S..Rivelli, A.R James, R.A. Condon, A.G. (Tony) Lindsay, M.P. Lagudah, E.S. Schachtman, D.P. & Hare R.A. 2002. Avenues for increasing salt tolerance of crops, and the role of physiologically based selection traits. Plant and Soil, 247, pp93-105. Qadir, M. 2010, Sustainable management of saline waters and salt-affected soils for agriculture: Proceedings of the Second Bridging Workshop Aleppo, Syria 15-18 Nov 2009. London: ICARDA. Rengasamy P 2002, Transient salinity and subsoil constraints to dryland farming in Australian sodic soils: an overview, Aust. J. Exp. Agric. 42, pp 351-361. Wallender, W.W., &Tanji, K.K 2011, Agricultural Salinity Assessment and Management. Sidney: ASCE Publications. Read More