Illinois
Fertilizer Conference Proceedings
January 28-30, 1991
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Harold F. Reetz Jr1
Growing corn for maximum profitability (or Maximum Economic Yield) requires a systematic approach to management decisions. Each decision should be studied in relation to how it interacts with other decisions. For example, the decision on planting date interacts with the decision on hybrid selection. Optimum soil fertility interacts with plant population, hybrid selection, tillage system, and several other decisions. That same' basic approach applies to all crops, including corn. Good management means looping at the details and developing a system of best management practices (BMPs) selected to most efficiently utilize the physical, financial, and environmental resources available. Detailed, site-specific management is the cornerstone of a profitable, and thus sustainable, crop production system.
There is a lot of discussion about the comparison of sustainable and conventional agriculture. But the technology incorporated into agriculture in the past has helped make it sustainable, and many of the innovations derived from conventional agriculture are the key to sustainability now and in the future. Sustainable agriculture has been defined in many different ways. In the final analysis, the system that is sustainable will be the system that is profitable and environmentally sound.
"Conventional" agriculture is composed of modern, site specific, progressive, science-based production systems where available and applicable technologies and inputs are used effectively and efficiently. Conventional agriculture shows concern for the environment as well as profitability. Conventional systems have evolved over time as being the most efficient and profitable. Today's conventional systems are the result of extensive research and education programs on the development, adaptation, and implementation of technology and production practices in a competitive system. Inefficient, resource-wasting practices have been eliminated and replaced with more efficient, best-management practices (BMPs). The development of conventional agriculture systems is a continuous process. New technology,. new problems to solve, and changes in the physical, economic, and political environment of agriculture drive this evolution.
The fertilizer industry was established in response to a need for nutrients beyond those readily available on the farm. The chemical pesticide industry developed in response to a need to control pests that reduced the potential yield and quality of crops produced by farmers. These industries have. grown, changed, and adapted in a continuing effort to meet the needs of farmers and ultimately, consumers. As potential threats to the environment from these products have been identified, the industry, and the dealers and farmers who use the products have changed their practices to "reduce the potential for contamination of the environment.
Following are some examples of the kinds of technological innovations that have been developed in conventional research and on-farm adaptation that contribute to the improved sustainability of agriculture. Farmers, dealers, and researchers must always strive to improve the system with which they are working. High yield management and the innovations that have been created in the pursuit of higher and more profitable yields form the basis for sustainability of U.S. agriculture. It is important that the research and education system in U.S. agriculture continue to follow that course of action so that the essential technological innovations for the future will be developed.
A systematic approach to management is basic to success. The following points outline key management strategies that must be implemented as a part of a site-specific plan for each field.
Setting yield goals. An important first step is to set a realistic yield goal -for each field. That goal should be 15 to 20 percent higher than the average of the last five years. Planning for above average yields helps to insure that the necessary production factors are in place to take advantage of a good growing season when it occurs. The "above average" growing seasons have the most profit potential, because extra production helps reduce fixed costs per bushel.
Yield goals should be challenging, but attainable without undue risk. If moisture is likely to be limiting in a high percentage of the years, yield goals may need to be more conservative. If a farmer's financial position is limited, it may also be necessary to be more conservative on yield goals. If goals are set unrealistically high, they may be too costly to achieve and the risk of not reaching it too high. If yield goals are too low, production inputs become a limiting factor in good years, and opportunities for increased profits are missed.
Planning. Once the goal is established, the next step is to develop and execute a plan to attain that goal. This planning should be done well in advance so that there is time to make adjustments in input factors to fit the plan. Each detail should be included. Then it is important to be sure the plan is executed. Even if weather conditions force changes in the plan, you will still have a strategy for action.
Identifying limiting factors. High profit management involves identification of factors that limit yields and systematically correcting them. For example, if corn yields are being limited due to lodging, it may be helpful to increase potassium levels in the soil to help improve standability. If weed competition is limiting yields, try to reduce weed populations with herbicides and/or mechanical cultivation. Take each limiting factor, one-at-a-time, and make the necessary management changes to reduce or eliminate its effect on yield.
Timeliness. A very important part of good management is to get all field operations done near the optimum time. Weather conditions affect timeliness, but planning ahead and getting equipment ready ahead of time can help avoid unnecessary delays. Make needed machinery repairs before the season begins to help avoid breakdowns. Delayed fertilizer application, for example, may cause a delay in tillage or planting operations. Again, interactions are important.
Integrated pest management. Weeds, insects, and diseases reduce potential yields. Integrated pest management (IPM), which involves identifying pest problems and using proper control measures, helps reduce costs by using only those pesticides or other controls needed for pests that are present in the field. IPM also involves using a proper system of chemical, biological, and mechanical control measures.
Soil testing. Taking accurate soil tests is an important step in planning a fertility program. Knowing the levels of essential nutrients in the soil provides the basis for determining the fertilizer applications needed to reach the yield goals. While not a perfect system, soil testing provides scientific input into the process of determining fertilizer application needs. Plant analysis provides another tool for determining nutrient use efficiency and for diagnosing crop needs for future nutrient applications.
Soil testing, calibrated with good field research response data, provides a means of determining the potential advantage of fertilizer applications. Farmers are using more detailed sampling grids to gain a better understanding of the variation of fertility levels within their fields, and to guide more carefully the application of fertilizers.
Building Soil Fertility: If soil tests are low for one or more nutrients, the first step is to build the level of that nutrient in the soil. Most corn growing areas have established potential yield relationships to soil test level.
Balancing nutrients: If one nutrient is not in adequate supply, it will reduce the crops' ability to efficiently utilize other nutrients. For example,. if soil potassium.(K) tests are low, the crop cannot fully utilize the nitrogen (N) fertilizer applied, so part of the money spent on N is wasted. Building soil K tests to the high range helps assure maximum efficiency of N utilization. While it is impossible to define the proper "balance" for all nutrients, it is important to avoid having inadequate soil nutrient supplies as a limiting factor.
Fertilizer program. A good fertilizer program supplies the growing crop with adequate amounts of all nutrients throughout the growing season. It should provide for the replacement of nutrients removed in the harvested grain, but it also must provide enough to grow the roots, stalks, and leaves, too, even though they are not removed from the field. Manure, sludge, and other nutrient sources can be a part of a good fertility program when they are available and cost-effective to use. Be sure to take appropriate credits in the fertility program.
Table 1. Total nutrients contained in corn grain and stover
When fertilizer is applied in alternate years in a rotation, be sure to apply enough to meet the needs of both crops.
Often there is a temptation to cut back on P and R when finances are tight. If soil tests are high, this may not initially reduce yields, but it can lead to problems if crop removal is not replaced over time. The importance of providing a balanced fertility program is illustrated in the following tables
Table 2. Long-term yield losses in corn without P and K.
Most efficient use of nitrogen fertilizer depends upon having adequate supplies of P and R available throughout the growing season. Without adequate P and R, some of the N may, be left at the end of the season, creating a potential for environmental problems.
Table 3. Balanced fertility increases yield and reduces production costs per bushel
Adequate P and K help improve corn yields and increase the utilization of N. This means more of the money spent on N fertilizer is returned in added yield,, and less in left in the soil to potentially be lost to the environment.
Table 4. Effects of P and R on corn yields and carryover of N.
Nitrogen management additives. Nitrification inhibitors or nitrogen "extenders" also provide a means of improving the efficiency of nitrogen utilization by the crop and may reduce the risk of nitrate contamination of water resources.
New application technology. Newer-technology fertilizer application systems use on-board computers on the fertilizer applicator to adjust fertilizer analysis and application rate as the machine moves across the field. The computer is programmed with a detailed soil test map showing areas where different rates and nutrient combinations are needed. This system helps the farmer provide nutrients at a uniform, optimum level. Higher nutrient rates can be applied to areas of the field where needed and lower rates can be used where soil test levels are adequate. Spoke-wheel injector systems are another new technology that offer some flexibility in timing and placement.
Concerns over the loss of valuable topsoil and the potential contamination of surface water supplies from soil erosion, along with the need to more efficiently utilize water resources, have prompted farmers to adopt conservation tillage systems. Reduced tillage and no-till systems have been in place on many farms for over 20 years in an effort to control erosion. University research and extension specialists, in cooperation with the chemical and farm machinery industry, have worked closely with farmers to develop and refine the management systems to make reduced tillage work. These practices have become the conventional systems in many erosion-prone areas.
Making this adjustment has required a systematic approach; beginning with farmer experimentation with new ideas, university and industry research into developing equipment and management systems for reduced tillage, and extension programs to spread the adoption of the practices. Maintaining surface cover throughout the sensitive parts of the year is a major part of the conservation tillage system. Increased residue production as a result of increased yields has been a major benefit of improved fertility management in conjunction with conservation tillage.
Ridge-till systems have evolved into workable management packages in recent years as the proper combinations of equipment, chemicals, and fertilizer placement have been determined. Residue and moisture, management, along with the proper complements of herbicides and cultivation, are key components.
Improvements in weed control systems, particularly through the use of herbicides, have been critical to the success of conservation tillage systems. Conservation tillage may mean different things to different people, ranging from elimination of one of several tillage operations to complete no-till systems. In general, it involves a reduction of the amount of tillage that is done to control weeds and prepare the soil for the following crop. According to the 1989 National Survey of Conservation Tillage Practices, 71 million acres of U.S. cropland were farmed with conservation tillage practices in 1989. Illinois led the nation with 8.2 million acres of conservation tillage, and also had the highest no-till acreage at 1.96 million acres.
Crop rotations have always been a part of conventional cropping systems wherever possible. The Morrow Plots at the University of Illinois have demonstrated the value of crop rotations since their establishment in 1876. Research as well as farmer experience has consistently shown the value of rotations. A common example in the Midwest is the corn-soybean rotation, which has been shown to have many advantages over monoculture systems. Weed control is improved, often with reduced use of herbicides. Reduced tillage is often used, with many farmers now using no-till corn planting systems in the soybean residue. Small grain/canola rotations in the Prairie Provinces, wheat/soybean rotations in the East and South, and wheat/sorghum rotations in the Plains are other examples.
Rotations may allow farmers to reduce nitrogen fertilizer use by taking advantage of the N produced by legumes in the rotation. Herbicide options may be increased to provide better weed control with less total chemicals applied in the system. The requirement for insecticides can also be substantially reduced or eliminated for some crops.
Extensive data are available from land grant universities documenting a 10-15 percent yield advantage for both crops in the corn-soybean system. Another advantage is that the machinery requirement is similar for both craps, and planting and harvest dates are not usually competitive.
Computerized soil test maps are being used as a part of a computerized record system that includes crop history, chemical and fertilizer use, crop yields, tillage systems, weather information, etc., along with concurrent economic information. Maps of these data can be "stacked" in the computer and overlaid on one another to draw correlations between physical characteristics, yield responses, management problems, etc.
This data base can be used for economic analysis of the farming system and projections of effects of management changes. Such systems will become more common in the next few years as more farmers, suppliers, and consultants are equipped with computer systems and software to collect and utilize the data bases. Joint efforts of universities, industry, and farmers are being focused on development of improved record keeping and interpretation systems that are an integral part of the management decision process.
Good records are essential. Crop records document practices used, growing season conditions, and yield levels. After several years of records are collected, they provide a history from which we can learn, and help provide a basis for planning management decisions and yield goals for the future.
A good record system should include the following:
- Soil survey information. Detailed soil maps of each field if possible, along with information about water holding capacity, root zone restrictions, etc.
- Soil test data. A map showing locations for each sample, along with tables of information on nutrient levels and recommended fertilizer applications.
- Fertilizer applications. Timing and amounts applied, method of application and placement, etc.
- Field operations. A list of each field operation, including date completed, and details such as depth of tillage, soil conditions at the time, etc.
- Planting data. List hybrids planted and their location in the field, planting date, planting depth, seeding rate, final population, etc.
- Pesticides used. Include chemical used and formulation, rate and time of application, weather conditions at time of application, and any other observations.
- Pest observations. Records of field scouting activity to determine pest problems. Include dates, kinds and numbers of pests identified, and a map of locations of major infestations.
- Weather records. Daily information on rainfall, temperatures, windspeed and direction, and relative humidity if available are useful for management decisions. Rainfall and temperature should be measured in the field; nearby weather stations may be used for the other information. Top farmers should consider using on-site weather instruments. They are useful in predicting crop development and pest problems.
- Yield records. Detailed yield information for each field (and for each individual hybrid in a field) will help identify management systems that are more profitable. Harvest moisture and observations on grain quality, standability, etc., are also helpful.
- Economic records. Include prices paid for inputs and prices received for grain sold. Detailed crop budgets can then be prepared to determine the profitability of the management system.
Innovations in planting equipment in the past 10-15 years have made it much easier to achieve a uniform planting depth and spacing of seed in the row, leading to more uniform populations and more uniform emergence and early growth of the crop, and ultimately increased yield potential. Specialized planting systems for different crops and different tillage practices have been very important improvements. Examples include no-till planters and drills, ridge planters, and better depth control and seed placement systems on conventional planters. Here, too, electronic monitoring and control systems are beginning to play a key role in developing site-specific adjustments of rates, depths, etc.
Plant breeders suggest that 30-50 percent of the improvement in crop yields over the past 50 years has been the direct result of improved varieties and hybrids. Experiments comparing older genetic lines with modern lines have proven these estimates to be accurate. Some of the major increases have been due to improved disease and insect resistance, but improvements in root development, water use efficiency, and physiological activity have also been made. More recent improvements, such as resistance to specific herbicides, promise to impact the overall management system by opening, up new weed control possibilities. These are some of the. first real benefits to be derived from genetic engineering and biotechnology research. Other variety improvements relate to crop quality or to specialty uses for the crop. Often farmers contract for a substantial premium from processors who want a specific variety or type of grain.
Hybrid selection. Choose hybrids well adapted to your area, with the proven ability to yield at the level of your yield goal. Select several different hybrids to help spread risk and to improve probability of taking advantage of favorable conditions at different times during the growing season. Planting some early-maturing and some late-maturing hybrids not only spreads risk, it also helps spread the workload at harvest time. Be aware of hybrid differences in response to other management factors.
Table 5 .Yield response to K is greatest with a high-yielding hybrid.
Conventional management systems for many years have incorporated integrated systems for pest control and general crop management. Cooperative efforts of university researchers, extension specialists, industry specialists, crop consultants, and growers have pulled together components of the complete management system to make best use of the resources available to the farm and to work toward the goal of maximum profitability and minimum impact on the environment.
Integrated Pest Management (IPM) has helped improve pest management programs and often reduce the unnecessary applications of pesticides. Regular scouting of fields for developing problems helps avoid disasters, while at the same time protecting the yield potential and quality of the crops produced.
Some farmers are carrying the concept further by adopting an integrated crop management system--ICM--which includes pest management, but also fertility management, crop rotations, production record analysis, and variety selection. Both IPM and ICM represent the growing trend toward the systems approach to crop management. Paying attention to all the details and attempting to optimize inputs relative to yield, profitability, and environmental stewardship, is a positive step toward true sustainability in crop production.
Pesticides of the future--including many of those now available--will be more concentrated, more specific in activity, and much less environmentally active. Biodegradable pesticides in biodegradable packaging will become the standard. Farmers will likely use more different types of pesticides in more different ways for specific pests and specific times, and will have to be more directly involved in site-specific, pest-specific decisions.
A variation of ICM is the MEY approach. It utilizes a system of best management practices (BMPs) to strive for the most profitable and environmentally-sound yield level. This will usually be just slightly lower than the maximum potential yield for the given soil-crop-climate system. Production inputs are evaluated and applied in the combination most likely to maximize profitability and to benefit the environment.
KEY systems require a high level of management. The appropriate BMPs to be used can be determined only through systems research projects, coupled with appropriate on-farm demonstrations and extension/consulting programs for site specific management planning. MEY and BMPs are moving targets. As economics change and/or new technology becomes available, the BMPs for MEY will change.
Programs for continuing education and communications for farmers have helped enhance the sustainability of conventional systems. Computer applications, videotapes, popular and scientific journals, newspapers, and magazines, help to keep the farmer up-to-date on latest management systems and technology developments. Leading farmers are now utilizing computer information networks for such services as market and weather information and pest advisories.
These programs are expanding and can be used to provide direct communications between the farmer and the various advisors upon whom he depends for information in making management decisions. Some may include short education programs on specific topics of interest to help keep the farmer informed on current recommendations of university and industry specialists, or training in the use of new technology.
Involvement of the non-farming public in policy-making in the 1990s will increase the need for communication among farmers and agribusinesses and consumers regarding the scientific and economic basis for farming practices and inputs, and open evaluation of the cost/benefit relationships. This type of communication is beginning to take place, but much more will be needed in the future.
The future sustainability of agriculture to meet the food, fiber and energy needs of society depends upon profitability. Improved efficiency, lower inputs-per-unit-of-output, higher yield potential, reduced erosion, are all part of the package. A solid research and extension program, coupled with programs of industry and commodity organizations to test and promote new technology are all important components of a truly sustainable agriculture.
But it is not enough for agriculture to be technically sustainable. It must be socially and politically sustainable as well. Consumers and elected officials must be better informed about agriculture, so that decisions relative to agricultural policy and attitudes relative to agricultural technology can be based on facts, rather than emotion. Conventional crop production systems, evolving with constantly improving technology based on sound research and education programs, remain the best, means of insuring a dependable supply of high quality food, fiber, and energy for our domestic needs and for foreign markets.
These simple guidelines form the foundation of the kind of management system--paying attention to details--that are essential to the development of a truly sustainable agriculture system. Profitable crop production demands a systematic approach to management. Each detail of the system is important and should be considered. Leave nothing to chance. Plan to take advantage of positive interactions wherever possible. Balance N fertilizer with adequate P and K to make most efficient use of fertilizer inputs. The goal should be to maximize profits---to approach Maximum Economic Yield.
Leading researchers, educators, dealers, and farmers who have taken up the high-yield challenge, have helped promote progress in the technology of agriculture to make crop production systems not only more profitable, but also more environmentally sound. Political rhetoric and special interests have caught much of the spotlight in recent years, but the real progress toward sustainability in agriculture is still grounded in the continued research and adaptation of better management practices that improve yields and efficiency in utilization of resources. High yield management has not gone out of style. It really needs to be given renewed emphasis if we are to continue to make the progress in technology needed to meet the challenges of the future.
Agriculture faces many new challenges as we move toward the 21st Century. But it has never faced a more exciting time t We in agriculture have no reason to apologize for our progress in developing and applying new technology. We should proudly point to the fact that our nation enjoys the safest, most abundant, and least expensive food supply in the world, and that farmers and agribusinesses have made great strides in recent years to ensure that our soil and water resources are better protected than ever before. High yields and high technology are not at odds with social and environmental responsibility. They work together. It is our challenge to make it so!
Table 1. Total nutrients contained in corn grain and stover
Table 2. Long-term yield losses in corn without P and K.
Table 3. Balanced fertility increases yield and reduces production costs per bushel
Table 4. Effects of P and R on corn yields and carryover of N.
Table 5 .Yield response to K is greatest with a high-yielding hybrid.
