title: Root Biomass under Range of Pasture Swards -Implications for Soil Carbon Stocks

authors: Jordan, Olivia Margaret

subjects: root biomass

abstract: Soil carbon (C) is the largest terrestrial store of carbon, greater than all other pools combined. Root biomass is recognised as an important contributor to the accumulation of soil C and recent studies have suggested that a higher diversity of plant species with higher root biomass may increase soil C content. Maintenance of soil C stocks is important as losses can contribute to increased greenhouse gas emissions. Furthermore soil C is important for maintaining soil quality. Much of New Zealand agricultural land is under pastoral grazing and is the greatest contributor to national greenhouse gas emissions from land. The potential for storing additional soil C in pasture soils is poorly understood. This study has assessed root biomass and carbon contents of soils under a range of pasture diversities and species composition to determine whether (i) there is greater root biomass under increasing plant diversity, (ii) changes in root properties between diversity treatments are evident and (iii) there is variation in root biomass between seasons. 
Soil samples were collected from an existing small plot trial managed by DairyNZ and Landcare Research containing 14 different mixtures of pasture species (three replicates per treatment). From each plot, fifteen soil cores were taken to a depth of 60cm, and bulked by 10cm depth increments. Root characteristics were determined after removing soil via scanning and analysing with WinRHIZO©, and subsequently root biomass determined following oven drying and weighing. A sub-sample of soil was also taken for C and nitrogen (N) analysis by combustion furnace. 
While there were no significant differences in root biomass with individual treatments, plots which had a presence of herb species chicory and plantain, resulted in a lesser root biomass when compared with plots without herb species. This would imply that while the use of herb species is desirable for above-ground production and drought tolerance, they provide limited potential for increasing C input to soil. Root characteristics determined that the use of tall fescue as a base grass resulted in a reduced root length density (RLD, root length per volume of soil to 60 cm), specific root length (SRL) and an increased average diameter compared with ryegrass based pastures. These characteristics promote increased root longevity in soil.

text: Root Biomass under Range of Pasture Swards -Implications for Soil Carbon Stocks Soil carbon (C) is the largest terrestrial store of carbon, greater than all other pools combined. Root biomass is recognised as an important contributor to the accumulation of soil C and recent studies have suggested that a higher diversity of plant species with higher root biomass may increase soil C content. Maintenance of soil C stocks is important as losses can contribute to increased greenhouse gas emissions. Furthermore soil C is important for maintaining soil quality. Much of New Zealand agricultural land is under pastoral grazing and is the greatest contributor to national greenhouse gas emissions from land. The potential for storing additional soil C in pasture soils is poorly understood. This study has assessed root biomass and carbon contents of soils under a range of pasture diversities and species composition to determine whether (i) there is greater root biomass under increasing plant diversity, (ii) changes in root properties between diversity treatments are evident and (iii) there is variation in root biomass between seasons. 
Soil samples were collected from an existing small plot trial managed by DairyNZ and Landcare Research containing 14 different mixtures of pasture species (three replicates per treatment). From each plot, fifteen soil cores were taken to a depth of 60cm, and bulked by 10cm depth increments. Root characteristics were determined after removing soil via scanning and analysing with WinRHIZO©, and subsequently root biomass determined following oven drying and weighing. A sub-sample of soil was also taken for C and nitrogen (N) analysis by combustion furnace. 
While there were no significant differences in root biomass with individual treatments, plots which had a presence of herb species chicory and plantain, resulted in a lesser root biomass when compared with plots without herb species. This would imply that while the use of herb species is desirable for above-ground production and drought tolerance, they provide limited potential for increasing C input to soil. Root characteristics determined that the use of tall fescue as a base grass resulted in a reduced root length density (RLD, root length per volume of soil to 60 cm), specific root length (SRL) and an increased average diameter compared with ryegrass based pastures. These characteristics promote increased root longevity in soil.

year: 2015

title: New ΔR for the southwest Pacific Ocean

authors: Petchey, Fiona

subjects: ΔR

abstract: ΔR results of known-age shells from the Solomon and Coral Seas and the northwest coast of New Ireland are presented. The results are too few to be conclusive but indicate that ΔR in this region is variable. An average ΔR value of 370 ± 25 yr is recorded for a range of shell species from Kavieng Harbor, New Ireland, and is primarily attributed to weak equatorial upwelling of depleted 14C due to seasonal current reversals. In contrast, values from the Solomon and Coral Seas are lower (average ΔR = 45 ± 19 yr). Higher ΔR values for some shellfish from these 2 seas is attributed to ingestion of 14Cdepleted sediment by deposit-feeding species.

text: New ΔR for the southwest Pacific Ocean ΔR results of known-age shells from the Solomon and Coral Seas and the northwest coast of New Ireland are presented. The results are too few to be conclusive but indicate that ΔR in this region is variable. An average ΔR value of 370 ± 25 yr is recorded for a range of shell species from Kavieng Harbor, New Ireland, and is primarily attributed to weak equatorial upwelling of depleted 14C due to seasonal current reversals. In contrast, values from the Solomon and Coral Seas are lower (average ΔR = 45 ± 19 yr). Higher ΔR values for some shellfish from these 2 seas is attributed to ingestion of 14Cdepleted sediment by deposit-feeding species.

year: 2004

title: Traditional Knowledge (TK) Labels Transforming Data Infrastructure to Recognise Indigenous Provenance

authors: Hudson, Maui

subjects: Data

abstract: Associate Professor Maui Hudson, KatieLee Riddle and Dr Janette Hamilton-Pearce introduced the latest developments and applications of the Traditional Knowledge Labels and the Local Contexts Hub with examples of use by researchers in Aotearoa New Zealand.

text: Traditional Knowledge (TK) Labels Transforming Data Infrastructure to Recognise Indigenous Provenance Associate Professor Maui Hudson, KatieLee Riddle and Dr Janette Hamilton-Pearce introduced the latest developments and applications of the Traditional Knowledge Labels and the Local Contexts Hub with examples of use by researchers in Aotearoa New Zealand.

year: 2022-09-27