Organic agriculture can pollute groundwater, research shows

Public demand has led to the rapid development of organic farming in recent years to provide healthy food products that are free of chemical additives and to reduce industrial and groundwater pollution worldwide.

But, according to the paper published in the Hydrology and Earth System Sciences journal, intensive organic matter using composted manure prior to planting resulted in significantly higher groundwater pollution rates compared with liquid fertilization techniques through drip irrigation.

The study used Vadose Zone Monitoring System technology developed at BGU and commercialized by Sensoil Innovations Ltd. to compare the water quality across the entire unsaturated zone under organic and conventional greenhouses in Israel.

The system is designed to monitor liquid, gas and soil hydraulic properties and allows real time continuous tracking of water in deep sections of the vadose zone, from land surface to groundwater. It is currently being used in more than 25 commercial and research sites in the United States, Israel, Spain, Namibia, and South Africa.

While groundwater pollution is usually attributed to a large array of chemicals, high nitrate concentration in aquifer water is the main cause for drinking-water well shutdowns.

The down leaching of nitrates under intensive organic farming is due to nutrient release from the compost to the soil during the early stages of the growing season. In this stage, nutrient uptake capacity of the young plants is very low and down leaching of nitrates to the deeper parts of the vadose zone and groundwater is unavoidable.

The study, funded by the Israel Water Authority, was conducted in commercial greenhouses on the Southern part of the coastal aquifer in Israel.