Optimising storage conditions and processing of sheep urine for nitrogen cycle and gaseous emission measurements from urine patches

Abstract

In grazing systems, urine patches deposited by livestock are hotspots of nutrient cycling and the most important source of nitrous oxide (N2O) emissions. Studies of the effects of urine deposition, including, for example, the determination of country-specific N2O emission factors, require natural urine for use in experiments and face challenges obtaining urine of the same composition, but of differing concentrations. Yet, few studies have explored the importance of storage conditions and processing of ruminant urine for use in subsequent gaseous emission experiments. We conducted three experiments with sheep urine to determine optimal storage conditions and whether partial freeze-drying could be used to concentrate the urine, while maintaining the constituent profile and the subsequent urine-derived gaseous emission response once applied to soil. We concluded that filtering of urine prior to storage, and storage at − 20 °C best maintains the nitrogen-containing constituent profile of sheep urine samples. In addition, based on the 14 urine chemical components determined in this study, partial lyophilisation of sheep urine to a concentrate represents a suitable approach to maintain the constituent profile at a higher overall concentration and does not alter sheep urine-derived soil gaseous emissions.

O uso de urina de ovino promove o desenvolvimento inicial do feijão-caupi (Vigna unguiculata (L.) Walp)

“…Embora haja uma abundante presença de nitrogênio no ar, sua disponibilidade é limitada por sua facilidade de perda no solo pelos processos de nitrificação e desnitrificação, o que resultam em uma absorção ineficiente pelas plantas, diante disto, torna-se necessário a aplicação de fertilizantes nitrogenados nas culturas (Charteris et al, 2021;Shi et al, 2013). Entretanto, o manejo errôneo da adubação nitrogenada, resulta em uma série de problemas ambientais, como a acidificação do solo, poluição da água, aumento das emissões de gases de efeito estufa e a perda da biodiversidade nas áreas agrícolas (Zhang et al, 2023).…”