5月の公開セミナー

Brent Clothier1,2, Karin Mueller1,2,3, Indika Herath1,2, Markus Deurer1,2, & Steve Green1

1 Plant & Food Research, PO Box 11-600, Palmerston North, NZ 4442;

brent.clothier@plantandfood.co.nz

2 New Zealand Life Cycle Management Centre, Massey University, Palmerston North NZ 4442

3 Plant & Food Research, Ruakura, Hamilton, NZ

The natural-capital concept integrates thinking about economics and ecology by conceiving ‘nature’ as ‘capital’. Beneficial ecosystem services flow from natural capital stocks. The natural capital value of soil depends critically on its stocks of carbon and water. Footprinting protocols for horticultural products are being developed to assess the impact of orcharding on natural capital stocks.

Metrics of life-cycle greenhouse-gas emissions, so called carbon footprints, are coming into in vogue. Supermarkets are seeking that the products they sell are labelled with a measure of their global warming impact. Supermarkets are the new regulators, and by their demands for footprinting information are choice editing on behalf of their customers. Footprints are becoming a criterion for shelf access in top supermarkets. The International Standards Organisation will be releasing its carbon footprint protocol next year. The role of soil carbon and standing biomass should be accounted for. We show how.

The rising pressure on our water stocks is also causing anxiety. Consumers are increasingly demanding information about how much water is ‘in’ the products they purchase. We present a hydrologically rational approach to water footprinting. Electricity is used in the life cycle of horticultural products and we quantify the water footprint of hydroelectricity.

Horticulture for the future must not compromise the ecosystem services that flow from natural capital stocks. By quantifying footprints, new orchard practices and supply chain processes can reduce the total footprint of fruit. Growers will then be profitable through securing shelf-access and eco-premium prices for their fruit in the top supermarkets.

K. Mueller1, M. Deurer2, T. Aslam2, B. Clothier2, I. Young3

1 Plant & Food Research, PO Box 3230, Hamilton, New Zealand 3240;

karin.mueller@plantandfood.co.nz

2 Plant & Food Research, PO Box 11-600, Palmerston North, New Zealand 4442

3 UNE University of New England, Armidale 2351, New South Wales, Australia

Soil organic carbon (SOC) is underpinning many ecosystem services that soils provide. In this project, we used two paired sites with the same soil type, land-use and climate but with significantly different topsoil OC contents to investigate the impact of SOC on the filtering function of soils. The first land use pair consisted of soils under adjacent organic and integrated apple orchards with a difference of 32% in SOC. The second land use was permanent pasture grazed by sheep, where the camp sites had a 28% higher SOC content than the non-camp sites. For both paired sites, we analyzed how the different carbon management systems affected soil biology and physical properties, and how this in turn impacted the filtering of the herbicide 2,4-D.

A higher SOC content was accompanied by a higher biological activity and macroporosity in both systems. The filtering efficiency for 2,4-D was slightly reduced in the low SOC-soil in the orchard systems, while it was improved in the low SOC-soil under pasture. Soil water repellency of the topsoil's pasture, which was positively correlated with SOC contents, compromised the soil's physical filtering. We conclude that carbon sequestration in topsoils can have negative implications for the filtering function of soils.