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The effects of urine nitrogen application rate on nitrogen transformations in grassland soils
- Source :
- The Journal of Agricultural Science. 157:515-522
- Publication Year :
- 2019
- Publisher :
- Cambridge University Press (CUP), 2019.
-
Abstract
- Urine is a critical nitrogen (N) input in temperate grazed grasslands and can drive substantial nitrous oxide (N2O) production in soils. However, it remains unclear how differences in the N input rate affect N2O fluxes and vary between different grassland soils. The effect of increasing urine N application on ammonium (NH4+), nitrite (NO2−) and nitrate (NO3−) concentrations and N2O production was tested in two grassland soils, a free-draining loam and an imperfectly drained sandy-loam. It was hypothesized that high-urine N application rates would lead to ammonia/ammonium (NH3/NH4+) accumulation influencing N transformation rates and N2O production which differ between grassland soils. Fresh cattle urine was applied at rates equivalent to 300 and 1000 kg N/ha in an aerobic incubation experiment. Soils were destructively sampled over 80 days to measure changes in inorganic-N and pH. The higher N addition rate was associated with elevated NH3concentrations up to day 35 in soils, probably inhibiting NO2−to NO3−reduction. In contrast, there was no inhibition of nitrification in the 300 kg N/ha treatment. Cumulative N2O fluxes were greatest from the 300 kg N/ha treatment for the loam soil, but were greater for the sandy-loam under the 1000 kg N/ha treatment. The results also show that differences in soil properties, in particular carbon availability, can be important in regulating N transformation and N2O production. Collectively, these results demonstrate the proposed mechanism of nitrification inhibition at high-N input rates, driven by either high NH3/NH4and/or increased levels of NH4HCO3from urea hydrolysis.
- Subjects :
- Denitrification
Chemistry
chemistry.chemical_element
04 agricultural and veterinary sciences
010501 environmental sciences
Ammonia volatilization from urea
01 natural sciences
Nitrogen
chemistry.chemical_compound
Animal science
Nitrate
Loam
Soil water
040103 agronomy & agriculture
Genetics
0401 agriculture, forestry, and fisheries
Animal Science and Zoology
Nitrification
Ammonium
Agronomy and Crop Science
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 14695146 and 00218596
- Volume :
- 157
- Database :
- OpenAIRE
- Journal :
- The Journal of Agricultural Science
- Accession number :
- edsair.doi...........8cd7478616e2c7f816d2ff9dd7d35396