|
|
 |
 |
| |
 Printable version |
Microbial activity under saline conditions: saline soils in the Relizane region of Algeria |
Cahiers Agricultures. Volume 1, Number 5, 335-40, Novembre-Décembre 1992, Étude originale
|
 Résumé
Article gratuit
|
Author(s) : Abdelkader Dellal, Amor Halitim |
Summary : Few studies have examined the properties of saline soils (especially Algerian) in terms of microorganism biology. As concerns the effects of salinity on microbial activity or nitrogen mineralization, the results obtained were limited, rather obscure and somewhat controversial. The experimental research has concentrated on the effects of adding salts to non-saline soils, and on naturally-occurring soil salinity and sodicity. The present paper aims at contributing towards understanding the effects of salinity and sodicity on microorganism numbers, N mineralization and release of CO2 from the respiration process. Soils were sampled from Relizane, Algeria, a region suffering from serious agricultural problems, due mainly to primary and secondary salinization. Three of the soils were saline (alkaline-saline) and two were non-saline (red mediterranean and vertisol). The three saline soils differed in salinity and sodicity levels. Samples were taken from the topsoil (30cm). Four incubation series were performed under conditions of controlled water content (0.1mPa) and temperature (27 ± 2°C).
The following measurements were made:
- count of microbial biomass after 20 days\;
- count of ammonifying, nitrous and nitric bacteria in saline soils over 70 days at 10-day intervals\;
- production of NH4, NO2 and NO3 following the addition of (NH4)2SO4 in saline soils over 49 days at 7-day intervals, and measurement of released CO2 in saline soils over 25 days.
Comparison with non-saline soils demonstrated that salinity reduced the microbial biomass. The effect was not linear but exhibited a threshold value of 15.7mS/cm, above which the microbial biomass dropped. |
Keywords : |
|
