Study of Salinity in Market Garden Production on the Togolese Coast

Abstract

Agriculture accounts for over 40% of Togo's GDP, and employs almost 65% of its working population. Market gardening, one of its sub-sectors, remains an important source of income and food self-sufficiency for rural and peri-urban populations. Among the peri-urban production zones, the coastline, by virtue of its geographical position, is sensitive to the salinisation of water and soil, as well as to sea spray. Salinity has a negative impact on market garden production. This study was therefore carried out to investigate the salinity of water and soil used in market garden production on the Togolese coast. To do this, measurements were taken of the electrical conductivity (EC) and pH of irrigation water and soil sampled in the Ablogamé and Agodéké districts, two production areas on the coastal strip. In each of these areas, water and soil samples were taken at three sites, with three samples per site, giving a total of six sites for analysis. At Ablogamé, the values for irrigation water ranged from 1113.67±3.06 µS/cm, 1971.67±9.24 µS/cm, to 1926.33±6.51 µS/cm and for Agodéké, they ranged from 756.67 ± 1.53, 1016.00 ± 1.00 to 1178.33 ± 0.58 µS/cm. This shows that, according to CIRAD and WHO standards, the water analysed is classified as "salty", with a variability of EC within the same production zone, the exception being one of the Agodeke sites, which has soft water according to WHO standards. The FAO, for its part, classifies all the waters as having slight to moderate restrictions for irrigation. Furthermore, the EC values obtained are moderately and slightly high. In addition, those of the Agodéké sites, located at around 83 to 108 m from the sea, in the erosive zone, are generally lower than those of the Ablogamé sites located in the accumulation zone, at around 288 m to 406 m from the sea. The pH of the water is slightly alkaline. As for the soil, the EC values are below the norms at all the sites studied, thus demonstrating the non-saline nature of the market-garden production areas on the Togolese coastal strip. The soil pH is neutral to slightly alkaline. There is therefore a dynamism in the Togolese coastal aquifers that requires further studies to improve the performance of vegetable production on this coast.