19 Nov 2009

IPNI Presentations at 2009 Tri-Societies Annual Meetings

IPNI Presentations at 2009 Tri-Societies Annual Meetings

At the 2009 Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America in Pittsburgh, IPNI participated with eight presentations. The following list contains the titles, authors, abstracts, and presentations for download.

A Method for Estimating Yield Losses From Nutrient Rate Reductions. T. Scott Murrell

Many farmers are finding themselves unable to pay for the entire quantity of nutrients recommended. A common question is, “How much yield loss can I expect if I cut my nutrient rates?” To answer this question, some estimate of the nature of crop response to nutrient additions is required. A commonly used mathematical model is a quadratic-plateau function. It is used both for its simplicity as well as its ability to adhere to the law of diminishing returns. Normally, least-squares techniques are used to fit this response function to data taken from studies involving incremental rate applications. However, at the farm level, such data sets normally do not exist. Instead, farmers may have data from a nutrient misapplication or from intentionally omitting a nutrient application. In cases where a lower than normal rate has been applied and a yield reduction observed, a quadratic-plateau response function can be reconstructed. Two data points are required: 1) the higher yield achieved at the normally applied rate and 2) the lower yield achieved at a reduced rate. The mathematical approach of estimating the coefficients of a quadratic response function requires that the normally applied rate be one of four possibilities: 1) an economically optimum rate; 2) a rate that maximizes yield; or a rate that is a known amount above that needed to either 3) optimize economic returns or 4) maximize yield. These four possibilities quantify a range of expected yield loss from rate reductions, helping the farmer to make more informed decisions about his or her nutrient management program.

A Method for Estimating Yield Losses From Nutrient Rate Reductions T Scott Murrell.pdf

Balancing Economic, Environmental and Social Goals in Nutrient Management. Paul E. Fixen

Application of the right nutrient source at the right rate, at the right time, and in the right place has recently become a commonly used phrase for describing appropriate nutrient stewardship within the context of sustainable cropping systems. Nutrient best management practices (BMPs) are the in-field manifestation of these four rights (4Rs). Moving beyond a slogan phase in discussing 4R nutrient management necessitates specification of how “right” is determined including the requirement of balanced support of the economic, social and environmental goals of sustainability. Such balancing is facilitated by defining sets of practical system performance indicators that are agreed to by stakeholders. Though the balancing is done by those that farm the land, definition of performance indicators and targets should be a shared task of stakeholders at farm, regional and national geographies. Sets of indicators usually include those reflecting crop yields and quality as well as those reflecting nutrient loss to the environment; and soil productivity and ecosystem services as well as net profit and resource use efficiencies; and many more that can pull a specific management decision in opposite directions. As balance is sought, practices offering benefits for multiple indicators hold premium value. A nutrient BMP is based on scientific research, often refined with adaptive management, that shows the practice provides the best combination of economic, social and environmental performance for the specific site in question. However, defining the “best combination” may go well beyond scientific principles to include value judgments.

Balancing Economic Environmental and Social Goals in Nutrient Management Paul E Fixen.pdf

Corn Acreage, Fertilizer Use, and Spring Nutrient Discharge in the Mississippi River Basin: Relationships and Impact On Hypoxia. Clifford Snyder

Hypoxia in the Gulf of Mexico has been monitored annually since 1985. There have been a number of scientific reports on the causes and effects of hypoxia. Discharge of nitrogen and phosphorus via the Mississippi River has been identified as significant associated factors. Spring discharge of nitrogen and phosphorus has been more strongly related to the annual size of the hypoxic zone than the annual flux of these nutrients. Public and scientific concerns about the impacts of expanded corn acreage, nutrient applications, and the demands for biofuels have increased. Will an expanded corn acreage associated with an increased biofuel demand contribute to increased nutrient flux to the Gulf, and a larger hypoxic zone? The relationships among spring nutrient flux, corn and soybean acreage, fertilizer nitrogen and phosphorus use, and hypoxia were examined for 1985 to 2008. Since the mid-1980s, spring discharge of nitrate-nitrogen, Kjeldahl nitrogen, total nitrogen, and total and orthophosphate phosphorus declined. The net inputs of nitrogen and phosphorus declined most notably in the Upper Mississippi and the Ohio Sub-Basins, and modestly in the entire Mississippi River Basin. These changes occurred while corn yields increased and fertilizer consumption remained relatively static. Trends in spring discharge of nitrate-nitrogen, total phosphorus and orthophosphate phosphorus against harvested corn acreage were negative from 1990 to 2008. The vigilance of farmers, the skills of their crop advisers, and the research and transfer of new management technologies are likely to determine the future of crop nutrient use efficiency. Improvements in crop nutrient use efficiency through a 4R stewardship (right source, right rate, right time, and right place) are considered essential to improve farm profitability and sustainability, to provide global demands for food, fiber, and biofuels, and to protect water and air resources.

Corn Acreage Fertilizer Use and Spring Nutrient Discharge in the Mississippi River Basin Relationships and Impact On Hypoxia Clifford Snyder.pdf

Evaluation of Nutrient Use Efficiency Using County and Hydrologic Unit Nutrient Budgets for US Cropland and Soil Test Summaries, 1987-2007. Paul E. Fixen, Quentin Rund, Ryan Williams, Tom W. Bruulsema, Clifford S. Snyder, T. Scott Murrell, and Harold F. Reetz Jr.

Several critical contemporary agricultural issues have the potential to impact nutrient budgets for U.S. cropland. Production of bioenergy can alter nutrient removal due to changes in crop species and plant parts harvested, and can alter nutrient additions due to production of bioash and changes in manure composition induced by feeding distillers grain. Climate change may cause changes in crop yields, cropping patterns, and soil processes. Accelerated genetic changes have been promised that could alter crop yields and nutrient use efficiency. Recent major changes in fertilizer costs and crop prices have altered farm fertilizer use decisions. And, government policy can cause shifts in all of the above. Considering the potential future impact of these issues, it is critical to understand the current status of nutrient budgets, temporal trends of those budgets, and relevant inferences about nutrient use efficiency. This project integrates multiple data layers to create county-level estimates of nutrient removal by crops, fertilizer applied, and excreted and recoverable manure nutrients. Data sources include USDA-National Agricultural Statistics Service, Association of American Plant Food Control Officials, USDA Agricultural Census, and the International Plant Nutrition Institute. Nutrient budgets and recovery efficiencies by the balance method were estimated for the five Census years from 1987 through 2007. Geospatial techniques were used to migrate the county data to eight-digit hydrologic units for watershed evaluation. The analysis reveals areas of both highly positive and highly negative nutrient budgets as well as correctable weaknesses in existing data for conducting such analyses.

Evaluation of Nutrient Use Efficiency Using County and Hydrologic Unit Nutrient Budgets for US Cropland and Soil Test Summaries 1987 to 2007 Paul E. Fixen et al.pdf

Fertilizer Use in North & South America. Terry L. Roberts

North and South America are among the world’s leading users of fertilizers. Global consumption was estimated at 165 million metric tons (Mt) of fertilizer nutrients in 2008. East Asia used the largest amount of N+ P2O5 + K2O, accounting for 37% of the world’s consumption. South Asia was second with 18% of consumption followed by North America at 14% and Latin America (including the Caribbean) at 10%. Last year global demand for fertilizer escalated and fertilizer prices increased following the price of cereal crops. Then with the global recession and financial crisis fertilizer demand fell, however the fundamentals driving the world’s need for fertilizer have not changed. This paper will outline the role of North and South America in future fertilizer demand and supply and discuss the 4R nutrient stewardship approach being employed to help ensure fertilizer nutrients are being used efficiently and effectively.

Fertilizer Use in North and South America Terry L Roberts.pdf

History and Global Perspective of Soil Sampling and Analysis. Paul E. Fixen

Soil testing and the commercial fertilizer industry became significant parts of North American agriculture at nearly the same time. Most soil test methods in use today are based on publications dated in the 1940s or 1950s, a time when fertilizer use was about 11% of current consumption. As fertilizer use grew, so did the need for science-based guidance of its management and most Land Grant universities initiated service laboratories to meet the need. The practice was encouraged not only by universities but also by the fertilizer industry as it was soon evident that soil testing was an excellent means of convincing farmers to fertilize. With time, the private sector realized that soil testing could be a profitable industry in itself and commercial laboratories gradually became the dominant supplier of the service to farmers and their advisers.

Soil sampling has always been a challenge and widely recognized as the greatest source of error in the soil testing process. The advent of variable rate fertilizer application technology forced changes in soil sampling protocols and greatly expanded study of how to better characterize within field variability. Controversies arose around numerous practices including size of grids, grid vs cell sampling, zone vs grid sampling, the role of soil classification maps, number of cores to composite, etc. Some controversies remain unresolved with the market place finding room for diverse practices. Soil sampling has a history of comfortable beliefs based on soil testing being a robust practice. Those beliefs may not always agree with reality.

Outside North America the role of soil testing today varies markedly from plant-based approaches for assessing regional nutrient needs where soil testing is only a research tool to cases where government run soil testing surveys have been performed periodically to guide nutrient use.

History and Global Perspective of Soil Sampling and Analysis  Paul E Fixen.pdf

Scaling up Site-Specific BMP Management for Global Impact. Harold Reetz

Site-Specific management systems offer farmers and their advisers the best tools for adapting best management practices to their farming operations. The data underlying the site-specific decision making progress have been made possible through a series of developments in technology combining GIS, sensors, record-keeping, and monitoring of various parameters. To fully realize the value of these data bases whether generated on the farm or obtained from other sources, decision-support tools must be employed. With the combination of tools and data that are a part of precision farming technology, farmers can identify and implement the true best management practices for their operations. The budget squeeze on farming systems under today’s economy requires all farmers to improve their efficiency of production by raising yields and reducing expenses in whatever ways they can, while maintaining the necessary balance needed to protect environmental and production resources. Adopting this approach at the field scale helps contribute to the outcome of providing sustainable cropping systems at state, regional, national, and even global scales. Site-specific management works applied at the local scale throughout the world creates aggregated benefits at the global scale. As more farmers adopt best management practices through site-specific management and decision-making on each field, the larger scale results can be realized for agriculture and society in general. This presentation will outline how such a local/global balance can be developed and some examples of steps being taken to make it a reality.

Scaling up Site Specific BMP Management for Global Impact Harold Reetz.pdf

Scientific Considerations for Allocating Funds to Various Fertilizer Nutrients. T. Scott Murrell

In unfavorable economic conditions, many farmers must make difficult decisions about how to allocate their limited funds across fertilizer nutrients. Making such allocations requires some knowledge about how two or more nutrient interact to affect yield. This paper uses a two nutrient interaction as an example to demonstrate techniques for 1) finding economically optimum combinations of two nutrients and 2) determining the optimum combination of nutrients under restricted fertilizer expenditures.

Scientific Considerations for Allocating Funds to Various Fertilizer Nutrients T Scott Murrell.pdf