Nitrite Instability in Three Manitoba Soils

Lakeland (pH 8.0), Wellwood (pH 7.1) and Holland (pH 6.2) soils were studied in relation to loss of mineral nitrogen involving nitrite. Incubation of sterilized soils, autoclaving, and air drying in the presence of nitrite resulted in nitrogen losses following a pH sequence, i.e., Holland > Wellwood > Lakeland soil. Nitrite losses were larger in the presence of high ammonium levels. The relationship to pH was mostly indirect, since less nitrite was lost from Holland and Well-wood soils after destruction of organic matter. The latter emerged as the prime factor in nitrite loss, mediating pH-dependent interactions. Less nitrite was lost chemically when the acid Holland soil was extracted with water or KCl solutions. The data suggest that many chemical factors in the soil system contributed to nitrogen loss via nitrite, and that no single mechanism was involved.