Journal article

Publication year: 2011

Pages: 1362-1371

Journal: Soil Biology and Biochemistry

Volume number: 43

Issue number: 6

ISSN: 0038-0717

DOI Link: https://doi.org/10.1016/j.soilbio.2011.03.014

Publisher: Elsevier

Abstract: 
The effects of repeated synthetic fertilizer or cattle slurry applications at annual rates of 50, 100 or 200 m(3) ha(-1) yr(-1) over a 38 year period were investigated with respect to herbage yield, N uptake and gross soil N dynamics at a permanent grassland site. While synthetic fertilizer had a sustained and constant effect on herbage yield and N uptake, increasing cattle slurry application rates increased the herbage yield and N uptake linearly over the entire observation period. Cattle slurry applications, two and four times the recommended rate (50 m(3) ha(-1) yr(-1), 170 kg N ha(-1)), increased N uptake by 46 and 78%, respectively after 38 years. To explain the long-term effect, a N-15 tracing study was carried out to identify the potential change in N dynamics under the various treatments. The analysis model evaluated process-specific rates, such as mineralization, from two organic-N pools, as well as nitrification from NH4+ and organic-N oxidation. Total mineralization was similar in all treatments. However, while in an unfertilized control treatment more than 90% of NH4+ production was related to mineralization of recalcitrant organic-N, a shift occurred toward a predominance of mineralization from labile organic-N in the cattle slurry treatments and this proportion increased with the increase in slurry application rate. Furthermore, the oxidation of recalcitrant organic-N shifted from a predominant NH4+ production in the control treatment, toward a predominant NO3- production (heterotrophic nitrification) in the cattle slurry treatments. The concomitant increase in heterotrophic nitrification and NH4+ oxidation with increasing cattle slurry application rate was mainly responsible for the increase in net NO3- production rate. Thus the increase in N uptake and herbage yield on the cattle slurry treatments could be related to NO3- rather than NH4+ production. The N-15 tracing study was successful in revealing process-specific changes in the N cycle in relationship to long-term repeated amendments. (C) 2011 Elsevier Ltd. All rights reserved.

Harvard Citation style: Müller, C., Laughlin, R., Christie, P. and Watson, C. (2011) Effects of repeated fertilizer and cattle slurry applications over 38 years on N dynamics in a temperate grassland soil, Soil Biology and Biochemistry, 43(6), pp. 1362-1371. https://doi.org/10.1016/j.soilbio.2011.03.014

APA Citation style: Müller, C., Laughlin, R., Christie, P., & Watson, C. (2011). Effects of repeated fertilizer and cattle slurry applications over 38 years on N dynamics in a temperate grassland soil. Soil Biology and Biochemistry. 43(6), 1362-1371. https://doi.org/10.1016/j.soilbio.2011.03.014