EFFECT OF SALT STRESS ON DECOMPOSITION OF ORGANIC MATTER AND NITROGEN MINERALIZATION IN ANIMAL MANURE AMENDED SOILS

As it is believed that soil salinity can alter the organic matter turnover process, the present study discussed the influence of soil salinity on the decomposition of organic matter and nitrogen mineralization in animal manure amended soils. A factorial combination of two soil types (saline and non-saline soils) with three types of animal manure (i.e. poultry manure, goat manure and cow dung) was used to assess the C and N mineralization. The amount of CO2-C released from both soils was not significant (P ≤ 0.05) until day 2 of incubation. However, as incubation progressed, the amount of CO2-C released from manure amended soils was found to be significantly (P ≤ 0.05) higher than that of the control. However in the case of cow dung amended soils, release of CO2-C was not much influenced by the salinity stress. The NH4-N content of both soils was found to be reached to the peak at day 14, followed by gradual reductions in all treatments. However, saline soil showed significantly (P ≤ 0.05) low NH4-N content compared to the non-saline soil. Though, the nutritional composition of applied manures was different, no significant (P ≤ 0.05) differences were found among the treatments in terms of N mineralization. Furthermore, no distinct pattern of treatment behavior could be observed for NO3-N contents also. However, the content of NO3-N was found to be dominated in non-saline soil throughout the incubation. Results could be concluded that the response pattern of C and N mineralization to salinity stress depended on the type of animal manure incorporate to the soil and duration of incubation. Key words: salinity stress, animal manure, decomposition of organic matter, nitroge