Frequently Asked Questions about No Sure Fix
- What is new about this report?
- What is nitrogen use efficiency (NUE)?
- Why is it important to increase NUE in agricultural crops?
- What does nitrogen use efficiency have to do with global warming?
- Biotech has been around for 20 years. Why hasn’t it produced any nitrogen efficient crops yet, and what are its prospects for the future?
- What are genetic side-effects (pleiotropy) and why are they important for NUE?
- Is genetic engineering more likely than other plant breeding techniques to produce nitrogen efficient crops?
- How do ecosystem approaches to improving NUE differ from GE, and why are they important?
- Precision farming—adjusting nitrogen fertilizer applications to fit the precise needs of crops—sounds like a good solution. Is it enough to fix the pollution problem?
- How does organic agriculture, and especially cover crops, manage nitrogen efficiently?
- What is the UCS prescription for substantially reducing the threat of nitrogen pollution?
- Will investments by the private sector be sufficient to develop all needed methods for improving NUE?
1. What is new about this report?
No Sure Fix is the first report we are aware of that both evaluates the prospects of genetic engineering (GE) for improving crops’ nitrogen use efficiency and places GE in the context of other approaches to reduce nitrogen pollution, especially traditional and enhanced crop breeding. Policy makers must evaluate the relative pros and cons of different approaches in order to make good decisions to reduce nitrogen pollution. This report offers such a comparison.
2. What is nitrogen use efficiency (NUE)?
All plants need nitrogen to grow and thrive, and most important crops require the addition of large amounts of nitrogen–whether in the form of synthetic fertilizer, manure, or plant material–to be highly productive. Crops do not assimilate all of the nitrogen that is added to the soil, but some crops, varieties of crops, and agricultural practices use nitrogen more efficiently than others. Nitrogen use efficiency (NUE) refers to how well an agricultural system uses the nitrogen available to it. Two common ways of considering NUE are the amount of added nitrogen needed to produce a given amount of a crop, and the fraction of potentially harmful applied nitrogen that is lost from the farm.
3. Why is it important to increase NUE in agricultural crops?
Today’s dominant industrial agriculture uses enormous amounts of synthetic nitrogen fertilizer in an effort to maximize yields of major crops such as corn, soybeans, and wheat. But much of that fertilizer is wasted. In the U.S. and many other countries, less than half of the applied nitrogen is used by crops. That costs farmers money, of course, but unused nitrogen also causes major environmental harm. In fact, many scientists consider nitrogen pollution to be one of our biggest global environmental problems. Several chemical forms of nitrogen, collectively called reactive nitrogen, are responsible for causing environmental harm. Excess reactive nitrogen from farm fields, in the form of nitrate, finds its way into streams and rivers and ultimately ends up in major bodies of water such as the Gulf of Mexico. There, it nourishes vast blooms of algae that are consumed by bacteria, depleting the oxygen in the water and causing “dead zones” in which valuable fish and shellfish populations cannot survive. Nitrate also contaminates drinking water wells. Exposure to too much nitrate can cause a blood disorder called methemoglobinemia (also known as “blue baby syndrome”) that is especially dangerous for infants and pregnant women. Another form of reactive nitrogen, nitrous oxide, is a potent greenhouse gas that also was recently identified as a major cause of stratospheric ozone depletion (see #4 below). Because of growing global population, and hence growing demand for food over coming decades, nitrogen use and pollution could rise dramatically if substantial efforts are not made to increase NUE.
4. What does nitrogen use efficiency have to do with global warming?
Industrial agriculture is a major contributor to global warming, producing a substantial amount of the world’s emissions of heat-trapping gases—carbon dioxide, methane, and nitrous oxide. Heavy use of fossil fuel-based nitrogen fertilizer is a significant part of the problem, as some of the synthetic nitrogen is converted by soil microbes into the greenhouse gas nitrous oxide, nearly 300 times more potent than carbon dioxide. According to the U.S. Environmental Protection Agency, agricultural soil management accounts for two-thirds of the nation’s human-caused emissions of nitrous oxide. Minimizing agriculture’s future impact on our climate will require significant increases in NUE.
5. Biotech has been around for 20 years. Why hasn’t it produced any nitrogen efficient crops yet, and what are its prospects for the future?
Several genes for NUE have been tested in transgenic plants since the 1990s, and some have shown promise. But no crops genetically engineered for NUE have been commercialized, and the public record suggests most such crops are at relatively early stages of development and face several possible hurdles to successful use. One possible barrier is that genes regulating nitrogen use likely have more complex genetic interactions with the plant genetic material than the few currently successful engineered genes, and therefore cause more genetic side-effects that often lead to undesirable agricultural properties. Genetic side effects may limit the success of these new genes, even when NUE is improved. Some NUE GE crops may be successful, but their prospects are uncertain at this time.
6. What are genetic side-effects (pleiotropy) and why are they important for NUE?
Genes do not function in isolation in any organism. Rather, they interact with and influence each other. When genes are manipulated by GE or conventional breeding, these interactions can lead to unintended side-effects that alter traits other than the intended one and lead to unintended changes in the crop. Genetic side-effects associated with GE have been frequently observed. But while the two types of widely commercialized genes for insect resistance and herbicide tolerance in crops have relatively limited interactions with other genes, genes under consideration for improving NUE typically have much more complex interactions in the plant, and many side-effects are associated with them. Specific side-effects can’t reliably be predicted by current science, often because they occur only in specific plant tissues, at certain stages of development, or under particular environmental influences, and therefore only extensive testing in the lab and the field is likely to identify many important side-effects of GE.
Although many genetic side-effects may be harmless, some can impair important agricultural properties of the crop (such as its ability to fend off pests or withstand stress), alter its nutritional properties, or result in the production of harmful substances. No Sure Fix evaluates unintended changes in the function of plant genes in several GE NUE crops, including the gene that may be closest to possible commercialization. Unintended alterations of a number of important crop genes have been found in GE NUE plants. While some of these complex genes may have success in the future, their side-effects may end up decreasing other valuable crop properties at the same time.
7. Is genetic engineering more likely than other plant breeding techniques to produce nitrogen efficient crops?
Unlike genetic engineering, traditional crop breeding has already improved NUE. Over the past several decades traditional breeding has improve wheat NUE by about 20 to 40 percent in several regions. Data on the genetic potential of crop genes associated with NUE suggest that traditional breeding, or breeding enhanced by increasing knowledge about crop biology and genetics, can continue to make substantial contributions to improving NUE. The limited data available so far do not reveal any advantages of GE over crop breeding for improving NUE. GE has not yet brought to commercial use any crops with improved complex traits like NUE. Comparisons between GE and traditional breeding in No Sure Fix show that there is no reason at this time to believe that improvements that might be accomplished by GE could not also be accomplished as quickly as using non-transgenic breeding methods.
8. How do ecosystem approaches to improving NUE differ from GE, and why are they important?
Ecosystem approaches consider the interactions of crops with the farm environment over time and space. GE and breeding focus on changes within the plant itself, and do not address how spatial and temporal factors affect NUE. The timing of nitrogen fertilizer application to match the varying needs of the growing plant over time is important for improving NUE—fertilizer applied when the crop cannot use it will cause substantial nitrogen pollution even for crops with high NUE. For example, large amounts of fertilizer applied in the fall (a common practice for economic reasons) are lost during the winter and early spring when crops are not growing. Approaches that consider NUE as part of the ongoing interaction of crops with the farm environment, such as precision farming, and cover crops and other practices used by organic agriculture, are needed in addition to plant improvement to achieve high NUE. No Sure Fix explores the pros and cons of ecosystem approaches and how they stack up compared to GE.
9. Precision farming—adjusting nitrogen fertilizer applications to fit the precise needs of crops—sounds like a good solution. Is it enough to fix the pollution problem?
Synthetic nitrogen fertilizer is often applied just once during the year, supplying a large amount of nitrogen that cannot be entirely assimilated by crop roots before much escapes to the wider environment. Precision farming aims to apply fertilizer in amounts that are adequate to attain desired yield without exceeding the amount that the crop can utilize. Spring application usually results in less loss than fall application, and some farmers split fertilizer applications between the beginning of the growing season and later in the year. But these simple practices are inadequate to fine-tune fertilizer application to the specific nitrogen needs of each crop. To be more precise requires technology such as GPS systems and remote crop sensors that may be out of reach of many farmers. And even with the use of precision agriculture methods, weather and other unpredictable events that occur after fertilizer applications may slow crop growth unexpectedly, leading to substantial nitrogen loss.
10. How does organic agriculture, and especially cover crops, manage nitrogen efficiently?
Organic agriculture emphasizes building soil quality through the addition of organic matter. Among the benefits of such systems is a reduction of nitrogen loss from the soil. Organic systems supply nitrogen to crops in organic forms, such as those found in livestock manure and legumes and other plants used as cover crops—crops grown to cover the soil when cash crops such as grains are not growing—which act as “green manure” when incorporated into the soil. These organic forms of nitrogen are part of proteins and other large molecules (in contrast to most reactive forms of nitrogen, which are small inorganic molecules). Organic nitrogen is often slowly broken down by microbes in the soil into smaller forms—especially inorganic forms—that can be utilized by crops. Cover crops are especially important for improving NUE because they can also remove excess reactive nitrogen from the soil. In particular, they are usually grown when the cash crop is absent—from fall through winter—when cash crop roots are not available to assimilate reactive nitrogen from the soil. In a large peer-reviewed study, cover crops reduced nitrogen loss from farms by 40 to 70 percent. In addition to reducing nitrogen loss, improvements in soil quality through cover cropping and other organic farming techniques also serve to reduce erosion, enhance carbon sequestration, and increase the soil’s capacity to hold water, thereby protecting crops against drought. Public policies aimed at encouraging practices that improve NUE should also consider the values of multiple positive or negative impacts of these practices.
11. What is the UCS prescription for substantially reducing the threat of nitrogen pollution?
No Sure Fix shows that the prospects for GE NUE crops are uncertain, and even if they are successful, they will not adequately address the challenges of nitrogen pollution. Therefore, UCS advocates the use of a spectrum of ecological and breeding approaches. So far, traditional breeding shows the most promise for improving the NUE of crops, while promising ecologically-based approaches like the use of cover crops are also needed. GE may also have a role if it can overcome possible barriers that it has not confronted in current GE crops. Ecosystem-based approaches, such as the use of cover crops or precision agriculture, complement crop-based approaches such as breeding or GE (which largely overlap in their potential). They accomplish this by focusing on improving NUE at times when the cash crops are not growing, or by improving the timing of nitrogen application to better fit crop growth. It will be important to provide adequate support to all complementary approaches to improving NUE.
12. Will investments by the private sector be sufficient to develop all needed methods for improving NUE?
Although the private sector is investing heavily in developing GE crops, other needed methods for improving NUE are neglected by industry and thus require more public sector support. Despite its proven success, public funding for traditional breeding (for NUE and other important traits) has declined globally over the past several decades. Cover crop systems have also received inadequate interest from a private sector that does not benefit from their development and adoption. Indeed, many of the major advantages of cover crops involve environmental improvements—such as the absorption of nitrogen after it has been applied, erosion reduction, and improved soil quality—that are not adequately valued by the market. And although leguminous cover crops and precision farming systems can greatly reduce farmer spending on increasingly expensive nitrogen fertilizer, they may increase other costs, making farmers reluctant to adopt them. It will therefore be critically important for the public sector to develop and provide incentives for these approaches. Also, because precision farming, organic methods, and cover crops require farmers to modify current farming practices, extension services will need to play a role in encouraging their adoption.
