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Short‐term N 2 O, CO 2 , NH 3 fluxes, and N/C transfers in a Danish grass‐clover pasture after simulated urine deposition in autumn
Author(s) -
Bol Roland,
Petersen Søren O.,
Christofides Calliopi,
Dittert Klaus,
Hansen Martin N.
Publication year - 2004
Publication title -
journal of plant nutrition and soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 1436-8730
DOI - 10.1002/jpln.200321334
Subject(s) - urea , chemistry , ammonia , zoology , nitrification , ammonium , nitrous oxide , pasture , urine , nitrate , loam , environmental chemistry , nitrogen , soil water , agronomy , ecology , biochemistry , biology , organic chemistry
Abstract Urine patches are significant hot‐spots of C and N transformations. To investigate the effects of urine composition on C and N turnover and gaseous emissions from a Danish pasture soil, a field plot study was carried out in September 2001. Cattle urine was amended with two levels of 13 C‐ and 15 N‐labeled urea, corresponding to 5.58 and 9.54 g urea‐N l –1 , to reflect two levels of protein intake. Urine was then added to a sandy‐loam pasture soil equivalent to a rate of 23.3 or 39.8 g urea‐N m –2 . Pools and isotopic labeling of nitrous oxide (N 2 O) and CO 2 emissions, extractable urea, ammonium (NH 4 + ), and nitrate (NO 3 – ), and plant uptake were monitored during a 14 d period, while ammonia (NH 3 ) losses were estimated in separate plots amended with unlabeled urine. Ammonia volatilization was estimated to account for 14% and 12% of the urea‐N applied in the low ( UL ) and high ( UH ) urea treatment, respectively. The recovery of urea‐derived N as NH 4 + increased during the first several days, but isotopic dilution was significant, possibly as a result of stress‐induced microbial metabolism. After a 2 d lag phase, nitrification proceeded at similar rates in UL and UH despite a significant difference in NH 4 + availability. Nitrous oxide fluxes were low, but generally increased during the 14 d period, as did the proportion derived from urea‐N. On day 14, the contribution from urea was 23% ( UL ) and 13% ( UH treatment), respectively. Cumulative total losses of N 2 O during the 14 d period corresponded to 0.021% ( UL ) and 0.015% ( UH ) of applied urea‐N. Nitrification was probably the source of N 2 O. Emission of urea‐derived C as CO 2 was only detectable within the first 24 h. Urea‐derived C and N in above‐ground plant material was only significant at the first sampling, indicating that uptake of urine‐C and N via the leaves was small. Urine composition did not influence the potential for N 2 O emissions from urine patches under the experimental conditions, but the importance of site conditions and season should be investigated further.