Over The Horizon

Soil Climate Indicators

The first recorded agricultural field experiments from 19th-century Britain are helping modern scientists in New Zealand make predictions about climate change in the next century.

Professor David Powlson is head of the Soil Science Department of the Integrated Approach to Crop Research organisation at the historic Rothamsted agricultural research station, where the first recorded scientifically-based crop experiments were carried out in the 1840s. Information gathered from rudimentary experiments led to the invention of superphosphate -- the fertiliser which has been essential to the development of New Zealand agriculture.

These days, scientists in New Zealand and Rothamsted are collaborating on common research into the cycling of organic matter in soil, an important aspect for sustainable land use and climate change issues. Soils represent the largest land reservoir of carbon, so soil changes influence the earth's carbon cycle, and consequently climate. Landcare Research scientist Kevin Tate and his group at Palmerston North have adapted concepts developed by British scientists, which Powlson says have had enormous influence around the world. The studies include measuring soil microbial mass -- the study of what microbes do in soil and their effects on other processes.

Microbiologists have studied individual microbes but it is useful to lump them together and look at them en masse. These are valuable concepts and the work done in New Zealand has opened up new areas of research.

Unique mathematical models developed at Rothamsted allow scientists to look into the future levels of organic matter in soils. Dr Aroon Parshotam in Palmerston North is updating the original work so it can be used in new ways. The results are being compared with findings from actual field experiments from 150 years ago to provide information on indigenous forests and grass systems for 20th and 21st century farmers.

The scientists hope to next look at the role of soil in destroying methane gas, an important greenhouse gas which is produced in large amounts by our cows and wetlands. The researchers are getting together to see how soil treatments can be used to destroy more methane, perhaps by manipulating the balance of different organisms in the soil, to complement future manipulations of animals themselves to reduce gas production.