English abstract
The problem of salinization in the Batinah coastal area dates back to the 1990's with the major identified cause being excessive groundwater abstraction. Seawater intrusion in the Batinah aquifers is still advancing at analarming pace. The present study estimates the on-farm economic damages caused by salinity. The study is based on a sample of 61 farms from four Willayat of Batinah, Barka, Musanaa, Suwaiq and Shinas. The data collected concerned farm size, salinity of groundwater, crop mix, crop yields and inputs use. Farms were divided into three groups according to their salinity levels, "Low Salinity", "Medium Salinity" and "High Salinity". A linear programming approach was used to maximize each type of farm gross margin under water, land and labor constraints. The economic losses incurred by farmers due to salinity were estimated by comparing the profitability of the three different farm types. Results show that the profitability in terms of gross margin in the "Low Salinity" farms equals O.R 2,197/ha which is 28% higher than in the "Medium Salinity" farms with a gross margin of O.R 1,581/ha and 71% higher than in the "High Salinity" farms. Profitability in the "High Salinity" farms is the lowest and is estimated at OR 638/ha. The linear programming approach was later used to test the adoption of the practices and salt-tolerant varieties tested in the Rumais Research Center during 2007-2009. Results showed that only the "Jinen" variety of tomato forms part of the crop mix of the "Medium Salinity" farms and represents around 62% of the cropped area of that farm type. Thus, by introducing this salt-tolerant tomato crop into the crop mix profitability could increase by up to 6%. In other words, the effect of salinity could be mitigated by 6%.
Results for the tested forage crops showed that sorghum is far from being profitable, since it is not selected by the linear programming model in the crop mix. The reduced costs of sorghum are around O.R 3,827/ha and O.R 3,746/ha respectively for the "MS" and the "HS" farms. This implies that this crop could not compete with the existing forages which have low cost of production. Furthermore, given the very high r cost, salinity related research on sorghum should be abandoned and efforts should be concentrated on improving the Rhodes grass and Alfalfa irrigation and management practices.
