Effects of lignosulfonate-fertilizer applications on soil respiration and nitrogen dynamics

Lignosulfonate (LS) has been used as a carrier for micronutrients and has the potential to improve macronutrient fertilizer efficiency, but little is known about the behaviour of LS fertilizer mixtures in soil. A laboratory study was conducted using ammonium lignosulfonate (2.67% wt wt −1 ) in combination with diammoniumphosphate (DAP), urea (U) and U+DAP incubated in a silty clay loam soil. The experiment monitored CO 2 evolution and NH 3 –N volatilization for 69 d and extractable soil N periodically for 38 d. Addition of LS initially increased CO 2 evolution, but only a small proportion (10–22%) of the LS-C was evolved as CO 2 . Lignosulfonate decreased urea hydrolysis slightly and reduced the proportion of added N volatilized from the LS+U treatment. Lignosulfonate treatments accumulated N in the form of [Formula: see text], suggesting that LS may inhibit nitrification. A larger proportion of added inorganic N was recovered in the LS + fertilizer treatments, indicating that LS may increase fertilizer N availability. Key words: Lignosulfonate, urea, diammonium phosphate, ammonia volatilization, nitrification, fertilizer efficiency