The Union of Concerned Scientists (UCS) recently released No Sure Fix: Prospects for Reducing Nitrogen Fertilizer Pollution Through Genetic Engineering by Doug Gurian-Sherman and Noel Gurwick. The focus is on nitrogen use efficiency (NUE), the degree to which crops utilize nitrogen as measured by crop yield per unit of applied nitrogen. Biotechnology companies have been pursuing NUE for about ten year and according to the report only 125 field trials have been approved by USDA. Biotech herbicide tolerant crops and insect resistant crops, some of which have been in commercial production since 1996, have had thousands of field trials.
NUE appears to result from a complex interact of plant genes and a single biotech gene may affect the function of many other genes. After outlining how biotech crops are studied, the authors forthrightly explain, “A relatively small number of field trials (which represent an intermediate step between growth chamber and on-farm studies) have been conducted, but the results of those trials—considered confidential business information—have not been released. Without comprehensive field studies, we cannot evaluate the promise of GE NUE crops under commercial conditions, or whether serious drawbacks such as impaired responses to drought or pathogens may emerge in the field.”
They then proceed to review the scientific literature about genes related to NUE. After raising more concerns about biotech NUE traits, the authors note, “There is not enough detailed information about the performance of GE NUE crops at this time to clearly understand their prospects for commercialization.”
The report does explain that traditional breeding of corn and other crops has improved NUE by increasing yields. According to industry data, commercial nitrogen fertilizer applications rates for corn were nearly unchanged at about 140 pounds per acres from 1994 to 2006, the last year for which data are available. Application rates per bushel of corn produced declined from about 1.2 pounds per bushel produced in the early 1980s to just over 0.8 pounds per bushel in 2006.
The efficiency improvements are now seen in university recommended application rates for nitrogen fertilizer. According to Fred Below, University of Illinois Crop Scientist, the recommended rate was 1.2 pounds of nitrogen per bushel of expected yield in the 1970s and had not changed much until recently. His studies of modern hybrids with spring application of nitrogen show an average requirement of 0.83 pounds of nitrogen per bushel of corn. He found that biotech rootworm resistant (Bt) corn hybrids have a higher NUE and yield primarily due to higher nitrogen uptake efficiency of 71% in Bt hybrids versus 55% in non-Bt hybrids.
With this progress on NUE, a logical thought is why seek out new technology when the current technology is effective. The UCS report answers that, “Any progress in nitrogen use we have made up to this point has not led to the decrease in nitrogen pollution we need.” The success to date on increasing NUE through conventional breeding and other means is not acceptable to groups like the USC which are driving the public policy agenda. Exploring ways for biotechnology to improve NUE appears to be is a reasonable response to an identified public policy issue.
In addition to more work in traditional breeding, the authors suggest two other avenues for improving NUE. Cover crops planted when the primary crops are not growing have been around for decades and can play a role in absorbing nitrogen for release again when the primary crop needs it, but fitting them into existing planting, harvesting and tillage practices is a major hurdle. The other suggestion is precision agriculture which focuses on accurate and timely placement of nutrients to have the right amount of nutrients available when needed by plants. Use of precision agriculture practices has been growing rapidly in recent years with the development of GPS and computerized data collection systems.
The report’s conclusions note that there is not a single approach to improving NUE. That is true for all of the challenges of increasing food production. Since there is no single solution, there is no reason to exclude biotechnology from the list of multiple solutions to improving NUE before its effectiveness has been determined. As the authors note, “No petition for deregulation of any NUE crop—a prerequisite for commercialization—has yet been announced by the USDA in its public database.” When that does occurs, we will have a better sense of the potential for biotechnology to improve NUE.
The report leaves the impression that U.S. seed companies are not investigating the variations of NUE that exists in corn and other plants that could be captured by conventional breeding. Seed companies seek out multiple solutions to production challenges. Pioneer, a major seed corn company, reports on its website that they are applying transgenic, molecular and conventional research to NUE. Fertilizer is the largest variable cost item for corn and reducing that cost would create a competitive advantage for a seed company regardless of the technology involved.
Public financing of non-biotech methods of increasing NUE is also recommended in the report. Public funding through land-grant universities supported much of the early research in plant breeding, but has played an increasingly smaller role in recent decades. With the obvious government budget problems at the federal and state levels, public funding is not likely to be a viable alternative any time soon.
Whatever is learned in the U.S. on NUE will be of value to the rest of the world. Alternatives should not be dismissed lightly before being fully explored.