Microbiological Transformations of Two Ammoniacal Fertilizers under Saline And/ or Organic Matter Fortification

In unsaline loam soil, a laboratory experiment was undertaken studying the effect of using diluted saline water from Karoon lake at Fayoum Governorate, on transformations and subsequent nitrification of two ammoniacal fertilizers, namely (NH4)2SO4 and urea, in the presence or absence of natural organic amendments, namely clover and wheat straw. Ammonification and nitrification of both fertilizers delayed, suppressed or inhibited by increasing salinity levels. Ammonification of urea appeared to be independent of salinity, but generally, nitrification was sensitive to it. Addition of narrow C/N organic supplements (clover) in non-saline soil enhanced ammonification and subsequent nitrification while wide C/N one (wheat straw) encouraged immobilization of mineral nitrogen. In presence of the organic supplements, salinity showed negative effect on ammonification and subsequent nitrification and even the mineralization process. Generally, the adverse effect of salinity on biological transformations of the two mineral N-fertilizers used was variably alleviated in presence of organic supplements.