Saturday, March 7, 2009

Less nitrogen could increase profit, sustainability

Science Daily: More fertilizer doesn't always mean more profit. That's one conclusion from a 10-year study conducted by Agricultural Research Service (ARS) scientists at the agency’s Soil Plant Nutrient Research Unit in Fort Collins, Colo., and colleagues at Colorado State University.

From 1998 to 2008, the researchers evaluated and compared potential management strategies for reducing nitrogen and nitrate nitrogen levels in soil and groundwater. The research, led by ARS soil scientist Ardell Halvorson, focused on irrigated cropping systems in the Arkansas River Valley, an agricultural region of Colorado that has high levels of nitrate nitrogen in the fields and groundwater--due, in part, to heavy application of nitrogen fertilizer and the prevalence of shallow-rooted crops such as onions.

The first study showed that onions used only about 12 to 15 percent of the fertilizer nitrogen applied to the crop. Much of the remainder stayed in the top six feet of soil. The next year, Halvorson and his colleagues planted corn on the same land and found that it recovered about 24 percent of the fertilizer nitrogen that had been applied to the onion crop.

…The results suggest that when managing fields with relatively high nitrogen levels, farmers could benefit economically from reduced nitrogen fertilization rates. Recommendations based on this research could have important economic and environmental benefits for the Arkansas River Valley and similar regions.

A walking path by the Arkansas River

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