Assessment and Management of Natural Resources of Coastal Gujarat towards Enhancing Productivity and Ensuring Food Security

Abstract

The Gujarat state is sharing the longest coastal line in the country i.e. 1600 km. Salinity problems are increasing at an alarming rate, more particularly in the irrigation command areas and coastal area. Out of 67.40 lakh hectares area affected by coastal and inland soil salinity/sodicity in the country, Gujarat has the largest salt-affected lands (21.05 lakh ha) which include 4.62 lakh ha coastal saline soils, 10.98 lakh ha inland saline soils and 5.45 lakh ha inland alkali soils. It is reported that Gujarat, in general received less rainfall during the period 1960–1990 compared to 1991–2008 and in particular Bharuch district received average annual rainfall of 753 mm during 1975-2011 as compared to 895 mm for the period 2000-2011. The average annual rainfall during the period 2000-2011 was increased by 19 per cent over long term average (1975-2011). It is also observed that the intensity of rainfall was more during later period of monsoon for 2000-2011 as compared to 1975-2011. Considering the climatic and edaphic factors, crops traditionally cultivated in Gujarat were highly appropriate. In Gujarat state the soils are ranging from sandy and saline to deep black clayey. Sand to sandy loam and saline soils are confined to the Kutch agro-climatic region and North Gujarat and partly to North Saurashtra. The soils predominantly found in Kutch are sandy and saline and receives the lowest rainfall in the state (346 mm per annum). The crops that have been traditionally cultivated in Kutch include pearl millet and sorghum. North Saurashtra has two dominant soil types: shallow to medium black and shallow to medium black calcareous. The average rainfall is about 633 mm per annum. While parts of North Saurashtra have medium black and poorly drained soils, South Saurashtra is completely covered with shallow to medium black calcareous soils. The average rainfall here is 877 mm per annum. Groundnut, sorghum, and pearl millet are the crops traditionally grown in South Saurashtra. Central Gujarat is covered with deep, medium black to loamy sand and sandy loam to sandy soil and average rainfall has been recorded at 822 mm per annum. The traditionally cultivated crops here are rice and cotton. South Gujarat, along with Southern Hills, characteristically comprises deep black clayey and deep black with coastal alluvial to medium black soils while the northern most region of South Gujarat is home to deep black to medium black poorly drained to loamy soils. The average rainfall in South Gujarat and the Southern Hills is 1207 mm per annum and 1819 mm per annum, respectively. The crops traditionally grown here include cotton, rice and sorghum. Gujarat witnessed an increase in groundwater extraction for irrigation purposes over the past two decades. This has been mainly caused by the shift in cropping patterns towards water intensive crops such as wheat, sugarcane, rice, and cotton. Seawater ingress besides marine influence creates huge salinity in the coastal regions. Salinity in coastal soils, unlike that in inland soils is caused during the process of their formation under marine influence and subsequently due to periodical influence of saline water either through inundation or capillary rise from shallow undergroundwater or saline water irrigation. Dominant salts occur in coastal saline soils are sodium chloride and sodium sulphate with loads of soluble cations with dominance of Na followed by Mg, Ca and K and chloride as the predominant anion followed by sulphate. The coastal land needs protection against tidal inundation through protective embankment like bio-shield for control of sea ingress, soil erosion and salinity. Monsoonal rainfall intensity has been increased during later period of Monsoon in the western coastal region. Unsuitable climatic conditions, soil and water degradation, marine influence in the coastal areas and secondary salinisation in irrigation command areas decreased the productivity of arable farming. Technological knowledge generated till date has helped in solving the problems in large tracts of land in different regions to restore their full productive potential. However, new challenges either due to changing climate or land use anomalies, leading to exponential increase in the area under salinity. With new challenges cropping up, soil salinity related stresses, particularly in coastal area are more pronounced and more damaging to crop production. The productivity of these soils can be restored by management and reclamation using different available technologies. Providing of adequate drainage, leaching out of soluble salts below root zone, cultivation of salt tolerant varieties/ halophytic plants, bio-saline agriculture, plantation of bio-shield including mangroves in coastal area, etc. have to be ensured for enhancing the productivity of these soils.