AgResearch

AgResearch


AgResearch

AgResearch is the host of the NZAGRC and is New Zealand's largest centre for pastoral agriculture research and development.


AgResearch includes teams of researchers with skills relevant to the Centre in rumen function, rumen microbiology, ruminant physiology, soil science, environmental science, agricultural systems management, forage plant growth and development, on-farm practice change, social science, technology uptake, genomics, proteomics and metabolomics of animals, plants and microorganisms.

www.agresearch.co.nz

                                                                                                     AgResearch
 

Sixty years of seasonal irrigation affects carbon storage in soils beneath pasture grazed by sheep

Kelliher, F. M., Condron, L. M., Cook, F. J., & Black, A. (2012). Sixty years of seasonal irrigation affects carbon storage in soils beneath pasture grazed by sheep. Agriculture, Ecosystems and Environment, 148, 29-36

Abstract

For sixty years at Winchmore, South Island, New Zealand (43°48′S, 171°48′E, 160 masl), stoney soils under continuous pasture grazing by sheep have received rainfall (nil irrigation) or rainfall and irrigation as required during summer. This consistently managed, replicated field trial presents a unique opportunity to examine long-term treatment effects on pastoral soil. Samples were recently excavated at intervals to a depth of 1 m and the total carbon (C) storage measured. In the irrigated plots, soil C storage (9.1 ± 0.3 kg C m−2, mean ± standard error, n = 3) was significantly less (p < 0.05) than in plots receiving rainfall alone (13.4 ± 0.8 kg C m−2). We estimated irrigation induced a 36% increase of C inputs to the soil on an annual basis, mostly as litter fall. Using a respiration model based on soil temperature and water content inputs, irrigation was also estimated to have induced a 97% increase in rate of annual C loss to the atmosphere. On this basis, the estimated irrigation effects had reduced C storage by 61% (97–36%), reasonably accounting for the 47% treatment effect determined by soil sampling.

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