Deep-rooted cover
crops can help potato growers prevent erosion and protect groundwater
by reducing nitrate leaching. That’s one conclusion of Agricultural
Research Service scientists who promote precision conservation –
a blend of conservation and precision agriculture.
Heavily fertilized crops with shallow roots, such as potatoes, are more
susceptible to nitrate leaching, says Jorge Delgado, a soil scientist
in the ARS Soil Plant Nutrient Research Unit at Fort Collins, Colo.
But nitrogen recovery can be improved and leaching reduced by using
a deep-rooted cover crop, such as winter rye, malting barley or winter
wheat.
Deep-rooted cover crops reduce wind erosion, sequester carbon, cycle
nutrients and draw nitrate further from the soil than shallow-rooted
crops.
Complementary potato research is being conducted in Prosser, Wash.,
and Orono, Maine.
In Prosser, scientists measured how much nitrogen Brassica cover crops
contributed to the soil and how much was taken up by subsequent potato
crops.
They found that 30 percent of the nitrogen on the field’s surface
was cycled back to the soil. Planting Brassica cover crops, such as
mustard, could save growers $15 to $20 per acre at current fertilizer
prices, researchers found.
Orono scientists used computer models to examine the temperature’s
effect on crop residue decomposition and nitrogen availability. They
want to find a way to predict the best time to apply additional fertilizer
to meet the crop’s needs.
