SALINITY OF SOIL AND IRRIGATION WATER ON RICE PRODUCTIVITY IN THE CANTON OF SAN JACINTO DE YAGUACHI, ECUADOR.

The surface of agricultural soils affected with salinity causes degradation and reduction of crop production, negatively impacting the economy of farmers. The objective of this research was to determine the effect of water quality and soil salinity on rice production in the sub-basin of the Yaguachi River, Ecuador. For this purpose, 99 soil samples were georeferenced and analysed over an area of 19 027 ha, as well as water samples representative of the area under study. Soil pH and electrical conductivity (EC) maps were produced and a regression analysis between EC and rice yield was performed on 34 producer plots. The predominant texture of the soils was found to be clayey, with an average pH of 6.73; The 38.4 % of the samples had an EC between 3.8 and 7.1 dS m-1. Rice yield gradually decreased as it was grown in soils with higher salinity and 26.81 % of the yield loss was found to be attributed to the increase in EC. The salinity of the irrigation water and other quality indicators such as the percentage of soluble sodium (Na+) and the sodium adsorption ratio (RAS) classified the water as severely restricted for use. However, given that crop yields did not show as drastic a reduction as expected, it can be said that the rice plant responds to the conditions of the canton of San Jacinto de Yaguachi as moderately tolerant to salinity. [ABSTRACT FROM AUTHOR]