Soil microbial biomass, CO2 and NH3 emission and nitrogen use efficiency in a sandy soil amended with recycled dairy products

Abstract

Re-cycling of wastes has many advantages to sustainable development, especially in arid and semi-arid conditions, where organic materials decompose with a high rate causing increases in gas emissions. The aims of this study were to explore the impact of expired dairy products (EDP) on soil microbial biomass and gas emissions from a sandy soil. The expired dairy products were converted to an organic fertilizer and the extracted fertilizer was evaluated in pot and incubation experiments as a nitrogen source for zucchini plants ( Cucurbita pepo L ). The trial consisted of four treatments i.e., control without any fertilization (C), urea (IF), EDP, and mixture of urea and EDP (MIX). EDP and MIX caused remarkable increases in nutrients availability and leaf uptake compared with C. EDP caused a 17% increase in the cation exchange capacity (CEC), in the other hand it reduced the soil pH by 8% compared with C. The maximum growth was found in zucchini plants that were fertilized with EDP or MIX. EDP and MIX increased the nitrogen use efficiency (NUE) by 37 and 25%, respectively, compared with IF. EDP improved the microbial biomass carbon and nitrogen (MBC and MBN) and this confirmed the eco-friendly behavior of EDP. EDP increased MBC and MBN by 20 and 21% compared with the inorganic fertilization. EDP increased the CO 2 emission and minimized NH 3 volatilization from the sandy soil. The extracted organic fertilizer is able to supply zucchini plants with its nutrient requirements; moreover, it is an ideal solution to recycle the expired dairy products. • Expired dairy products were converted to an organic fertilizer (EDP). • EDP enhanced the availability and uptake of nutrients. • EDP increased nitrogen use efficiency by 37% above urea fertilizer. • EDP enhanced the soil microbial biomass. • EDP increased the CO 2 emission and minimized NH 3 volatilization.