Influence of salinity on the biological and biochemical activity of a calciorthird soil

Irrigation of agricultural land with saline waters can lead to soil degradation. In this paper the effect of the irrigation with water containing different concentrations of NaCl or Na2SO4 (0.1 M, 0.3 M, 0.6 M, 0.8 M, 1 M, and 1.3 M) on the biological and biochemical characteristics of a calciorthid soil was studied. In general, the increase of soil electrical conductivity caused by the addition of saline solutions had a negative effect on soil's biological and biochemical fertility, (that related directly with the soil's microbiological activity) this effect being more noticeable with NaCl than with Na2SO4. Soil microbial respiration was inhibited as much as 57% by a 1.3 M solution of NaCl. The activity of hydrolases such as protease, beta-glucosidase and phosphatase was more negatively affected by salinity than that of oxidoreductases (dehydrogenase and catalase). Soil NO3- content decreased with salinity while NH4+ content increased. Carbohydrate content, which is closely connected with soil aggregate stability, was also negatively affected by salinity.