Nitrate leaching losses during pasture renewal - Effects of treading, urine, forages and tillage.
Sci Total Environ
; 651(Pt 2): 1819-1829, 2019 Feb 15.
Article
em En
| MEDLINE
| ID: mdl-30316098
ABSTRACT
Pasture renewal is a key component of intensive temperate grassland farming. This practice is performed to improve pasture yields, but it may increase nitrate (NO3-) leaching losses, which can impact on water quality. Farmers face many choices when renewing pasture, however, there is limited information to guide decisions to reduce leaching losses. An experiment was established to study how different management practices and grazing affect biomass production and NO3- leaching during pasture renewal on a heavy soil. Long-term pasture was either re-sown into ryegrass (Lolium perenne) in autumn (GG) or into forage rape (Brassica napus) followed by ryegrass in spring (GCG). Rape was established following ploughing or direct-drilling. Grazing was simulated in winter, whereby split plots ±urine (600â¯kgâ¯Nâ¯ha-1) and ±treading were established. Nitrate concentrations at 1â¯m depth were measured with suction cups and drainage predicted using a crop model. Estimated NO3- leaching losses at 1â¯m depth ranged from 16 to 38â¯kgâ¯Nâ¯ha-1, with little difference between GCG and GG. However, the risk of future leaching was much greater below GCG plots. At the end of the study, soil NO3- between 0.6 and 1â¯m ranged from 28 to 130â¯kgâ¯Nâ¯ha-1 in GCG plots and 1-28â¯kgâ¯Nâ¯ha-1 in the GG plots. Timing of leaching differed between renewal systems, reflecting the differences in plant N uptake and fallow period. Overall, there was no difference in dry matter production between the two systems. Treading resulted in greater compaction, especially in tilled plots and reduced NO3- leaching by c. 40% - this can be attributed to increased denitrification. Our study demonstrates the complex nature of management and environmental factors and their interaction during pasture renewal. We show that management practices affect the risk and timing of N leaching. Practical implications for farmers are discussed.
Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Solo
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Lolium
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Monitoramento Ambiental
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Brassica napus
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Criação de Animais Domésticos
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Nitratos
Tipo de estudo:
Prognostic_studies
País como assunto:
Oceania
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article