Lucerne To Mop Up Dryland Salinity

January 14, 2000 The Rural News

Effective pasture management may halt rising water tables and could prevent dryland salinity, soil acidification and water logging.

Dr Mark Peoples, of CSIRO Plant Industry, says excess water is a serious problem across agricultural land in Western Australia, New South Wales and Victoria.

Excess water drains into watertables causing them to rise and contributing to devastating and potentially irreversible environmental problems such as dryland salinity.

"Land degradation from excess water in the watertable now Costs Australia over $600 million dollars a year in lost agricultural production alone - and it's getting worse,' says Dr Peoples. "It is an extremely serious problem. Annual crops, such as cereals and grain legumes, are relatively shallow rooted. Rainwater escapes from their root zone to accumulate in the soil causing deep drainage and rising watertables," Dr Peoples says.

CSIRO research has shown that the vigorous, deep roots of perennial pastures like Lucerne are highly effective at removing water from deep in the soil and controlling this problem.

"In one Western Australian case study, the water table has been failing by half a metre a year for over five years under Lucerne," says Dr Peoples.

"In New South Wales we're seeing the soil dry out to double the depth it would under annual crops. If we can stop watertables rising, we can prevent salinisation of the land.

"Because perennial pastures use water for a longer period than annual crops and pastures and have deep roots, they remove more water from the system on an annual basis,' said Dr Peoples. Perennial pastures have been used for some years in the United States to mop up excess water".