Purdue University, Indiana, agronomist Jim Camberato offered New Zealand farmers an insight recently while visiting a Foundation for Arable Research field day on the organisation’s northern crop research farm near Hamilton.
Camberato has been closely involved in helping formulate nutrient management for nitrogen-hungry corn (maize) crops throughout the United States.
“It has required us to take a very neutral, science-based approach to formulation – we do not lean to environmentalists’ views, nor to farmers, [we] just try to provide evidence first and form the regulations from that,” he said.
However, he acknowledged the high level of public attention the sector was drawing, even in heavily agricultural US states.
A recent intense series of storms in North Carolina had 100 municipalities forced to discharge raw sewerage into local rivers. At the same time a local swine farm had a breach in its lagoon.
“But all the emphasis was upon that swine farm, despite 110 municipalities legally discharging raw human sewerage to rivers.”
The regulations around farming now include requiring farmers to conduct a one-metre deep nitrogen test.
“One of the requirements of formulating such laws was to teach farmers how to do these things for a certification process,” Camberato said.
But formulating regulations in such a way that farmers would be able to adopt them was a relatively complex route, with farmer groups having to be prepared to deal with environmental groups that were “well-lawyered”.
“Individual states are able to modify US federal environmental rules to be more stringent if they wish, but not less. They can also be adapted at a county level, but it is usually a state-by-state basis.
As a crop, corn is nitrogen hungry with input levels as high as 250kg nitrogen/ha in some of the eastern Corn Belt states that produce about two-thirds of the US corn crop.
Controls on application in many states is often to modify the effect hundreds of kilometres away, including water quality decline in the Gulf of Mexico and Chesapeake Bay, vital fishery and recreational assets.
“More than half the nitrogen reaching the Gulf of Mexico via the Mississippi River is attributed to nitrogen loss from agricultural fields in the Corn Belt.”
States in the Mississippi River Basin have voluntarily adopted plans to reduce nitrogen loss from fields with nutrient applications regulated by laws in areas draining to the Chesapeake Bay area.
With almost three-quarters of the nation’s drinking water sourced from ground wells, nitrate contamination is a big concern in some areas.
As NZ farmers work to knock nitrogen-loss levels down to below roughly 40kg nitrogen/ha, these figures would often be regarded as “best case” by many researchers in the US. A loss of 15kg nitrogen/ha would be the best that growers could expect.
“If we had to go lower we would definitely have to consider using wetlands and treatment processes,” Camberato said.
However, despite initial farmer resistance, the nitrogen regulations that have been adopted have generally resulted in “win-win” farming practices for profit and the environment.
“Most of the regulations have not really cost a lot more, and the greatest cost with them has been the time spent record keeping.”
South Carolina farmers were typically resistant to changes in behaviour the rules required, including the timing of fertiliser application so that nitrogen losses were minimised.
“Rather than putting it on early, we suggested wait until nearer planting – putting it off, they got a better response.
“In other cases they were using manure as a nitrogen source – we proved it was a lower-value nitrogen source and suggested they sell the manure to farmers who needed it as phosphate or potash source, and use a more efficient nitrogen source.”
Camberato acknowledged adoption had been slow, but it had moved a long way from 100% opposition in the early stages.
“Once they saw there were no negative effects, and in fact positive benefits, it has become second nature.”
