For maize (Zea mays L.), nitrogen (N) fertilizer use is often summarized from field to global scales using average N use efficiency (NUE). But expressing NUE as averages is misleading because grain ...increase to added N diminishes near optimal yield. Thus, environmental risks increase as economic benefits decrease. Here, we use empirical datasets obtained in North America of maize grain yield response to N fertilizer (n = 189) to create and interpret incremental NUE (iNUE), or the change in NUE with change in N fertilization. We show for those last units of N applied to reach economic optimal N rate (EONR) iNUE for N removed with the grain is only about 6%. Conversely stated, for those last units of N applied over 90% is either lost to the environment during the growing season, remains as inorganic soil N that too may be lost after the growing season, or has been captured within maize stover and roots or soil organic matter pools. Results also showed iNUE decrease averaged 0.63% for medium-textured soils and 0.37% for fine-textured soils, attributable to fine-textured soils being more predisposed to denitrification and/or lower mineralization. Further analysis demonstrated the critical nature growing season water amount and distribution has on iNUE. Conditions with too much rainfall and/or uneven rainfall produced low iNUE. Producers realize this from experience, and it is uncertain weather that largely drives insurance fertilizer additions. Nitrogen fertilization creating low iNUE is environmentally problematic. Our results show that with modest sub-EONR fertilization and minor forgone profit, average NUE improvements of ~10% can be realized. Further, examining iNUE creates unique perspective and ideas for how to improve N fertilizer management tools, educational programs, and public policies and regulations.
•We evaluated ability of a crop model to predict local and regional maize yield and production without calibration of internal parameters.•Yield potential was simulated for a wide range of ...environments in the US Corn Belt using a well-validated maize simulation model.•Simulated yield and total production were compared against actual yield and production at four different spatial scales.•We developed an approach to estimate actual yields based on year-specific simulated yield and long-term mean simulated and actual yields.•The proposed approach was robust at reproducing actual yield and total production.
Crop simulation models are used at the field scale to estimate crop yield potential, optimize current management, and benchmark input-use efficiency. At issue is the ability of crop models to predict local and regional actual yield and total production without need of site-year specific calibration of internal parameters associated with fundamental physiological processes. In this study, a well-validated maize simulation model was used to estimate yield potential for 45 locations across the U.S. Corn Belt, including both irrigated and rainfed environments, during four years (2011–2014) that encompassed diverse weather conditions. Simulations were based on measured weather data, dominant soil properties, and key management practices at each location (including sowing date, hybrid maturity, and plant density). The same set of internal model parameters were used across all site-years. Simulated yields were upscaled from locations to larger spatial domains (county, agricultural district, state, and region), following a bottom-up approach based on a climate zone scheme and distribution of maize harvested area. Simulated yields were compared against actual yields reported at each spatial level, both in absolute terms as well as deviations from long-term averages. Similar comparisons were performed for total maize production, estimated as the product of simulated yields and official statistics on maize harvested area in each year. At county-level, the relationship between simulated and actual yield was better described by a curvilinear model, with decreasing agreement at higher yields (>12Mgha−1). Comparison of actual and simulated yield anomalies, as estimated from the yearly yield deviations from the long-term actual and simulated average yield, indicated a linear relationship at county-level. In both cases (absolute yields and yield anomalies comparisons), the agreement increased with increasing spatial aggregation (from county to region). An approach based on long-term actual and simulated yields and year-specific simulated yield allowed estimation of actual yield with a high degree of accuracy at county level (RMSE≤18%), even in years with highly favorable weather or severe drought. Estimates of total production, which are of greatest interest to buyers and sellers in the market, were also in close agreement with actual production (RMSE≤22%). The approach proposed here to estimate yield and production can complement other approaches that rely on surveys, field crop cuttings, and empirical statistical methods and serve as basis for in-season yield and production forecasts.
In an irrigated multi-crop production system, farmers make decisions on the land allocated to each crop, and the subsequent irrigation water application, which determines the crop yield and ...irrigation water use efficiency. This study analyzes the effects of the multiple factors on farmers’ decision making and economic irrigation water use efficiency (EIWUE) using a national dataset from the USDA Farm and Ranch Irrigation Survey. To better deal with the farm-level data embedded in each state of the U.S., multilevel models are employed, which permit the incorporation of state-level variables in addition to the farm-level factors. The results show higher costs of surface water are not effective in reducing water use, while groundwater costs show a positive association with water use on both corn and soybean farms. The adoption of pressure irrigation systems reduces the soybean water use and increases the soybean yield. A higher EIWUE can be achieved with the adoption of enhanced irrigation systems on both corn and soybean farms. A high temperature promotes more the efficient water use and higher yield, and a high precipitation is associated with lower water application and higher crop yield. Intraclass correlation coefficients (ICC) suggest a moderate variability in water application and EIWUE is accounted by the state-level factors with ICC values greater than 0.10.
Switchgrass (Panicum virgatum L.) and miscanthus (Miscanthus × giganteus) have potential to meet a growing demand for renewable energy feedstock. Before producers will invest in planting these crops, ...they need credible estimations of the potential profits. The objective of this study was to examine profitability of growing these perennial bioenergy grasses, incorporating uncertain prices and yields in the model. The model compared the profitability of five crops {switchgrass, miscanthus, corn Zea mays L., soybean Glycine max (L.) Merr. and tall fescue pasture Festuca arundinacea} on three soil profiles common in northeastern Missouri: an upland, noneroded soil, an eroded soil, and floodplain soil. The effect of the USDA Biomass Crop Assistance Program (BCAP) and crop insurance on the decision to grow switchgrass and miscanthus was analyzed. Actual grain yields, Agricultural Land Management Alternatives with Numerical Assessment Criteria (ALMANAC) modeled grass yields, and Food and Agricultural Policy Research Institute (FAPRI) baseline prices were used to simulate profit. The results were compared using cumulative distribution functions (CDFs). Corn production was always chosen by decision makers of all risk attitudes to other crops. Miscanthus was always more profitable than switchgrass. Based on the CDFs, perennial bioenergy grasses were more likely to be planted in eroded soils currently in pasture production; however, there were scenarios in which they could be planted on eroded cropland currently planted to soybean. Lastly, crop insurance for corn and soybean could affect the decision to plant perennial bioenergy grasses for risk averse producers.
Nitrogen fertilizer is one of the most important inputs to corn production and farmers manage their crop by deciding how much to apply, when to apply it and how to apply it to maximize their yields ...and resulting profit. There is risk inherent in crop fertility management because once nitrogen is applied to the soil it is no longer immobile and cropland is subject to loss of this costly input under different weather conditions. Days suitable for field work, a farm’s machinery set, and weather conditions determine when field preparation and planting activities are completed each year. This paper documents the methods and data used to evaluate the economic costs and benefits of the agronomic practice of “splitting” nitrogen fertilizer—applying some at or just before planting and a second application after the plant has already emerged and is in greatest need of nutrients. An example of how to use the free online decision support tool Corn Split NDST (splitn.agclimate4u.org) to evaluate the climate risk and economics of post-planting N applications is developed to illustrate the application of methods described.
Early-seeded soybean Glycine max (L.) Merr. relay intercropped into standing wheat (Triticum aestivum L.) using soybean seed-coat technology may allow profitable wheat production in the Midwest on ...highly erodible soils. Dry conditions in mid- to late June have reduced relay intercropped soybean stands and yield in some years. We hypothesized that using glyphosate as a wheat harvest aid would reduce the impact of wheat interference on relay intercropped soybean grain yield and increase gross margins. Field research conducted over four site-years in upstate Missouri evaluated timings for application of glyphosate as a harvest aid on wheat and relay intercropped soybean. The cost effectiveness of these cropping systems was compared to full-season soybean, double-cropped wheat–soybean, and wheat-only production systems. Glyphosate applied to wheat 1 wk before harvest, after late dough, in a relay intercrop production system with coated-soybean maintained wheat grain yields similar to nontreated wheat, and increased soybean grain yields 290 to 770 kg ha−1 compared to nontreated wheat relay intercropped or double-cropped with soybean. Earlier glyphosate application timings (2–3 wk before wheat harvest) reduced wheat grain yields 10 to 25% and grain density 3 to 13%, but soybean yield increased 430 to 520 kg ha−1 compared to nontreated wheat in a relay intercrop system. A relay intercrop system with seed coat technology and glyphosate as a harvest aid may allow farmers to maintain wheat in their crop rotation while minimizing risk associated with early fall frost or dry conditions at seeding that may otherwise decrease double-crop soybean yields.
•Manure application limits impact farmer economic outcomes and probability of runoff.•Nitrogen limit takes least amount of time, but diminishes value of manure.•Annual phosphorus application limit ...costs farmers time and money; increases probability of runoff.•Phosphorus banking limit maximizes farmer income and decreases probability of runoff.
Three manure application limits – nitrogen limit, annual phosphorus limit, and multiple-year phosphorus limit (P Banking) are modeled to compare economic profitability and probability of application prior to a runoff causing rainfall event. Particular attention is given to the number of hours needed and available to distribute manure under each limit. Benefits are estimated as the foregone fertilizer applications. Costs are estimated based on the hours needed for manure management. The benefit and cost estimates indicate that P Banking was more profitable than nitrogen limit, which was more profitable than annual phosphorus limit. The number of hours required indicated that the annual phosphorus limit would not be completed within a five-week window approximately 2 of 10 years. If further restrictions based on precipitation forecasts were imposed, the likelihood of completion decreased to 6 of 10 years. The results of the study indicate that regulations that require annual phosphorus limit of manure cost the farmer and may have the unintended consequence of increasing runoff. P Banking would be the preferred manure application rule for both increasing farmer net income and reducing probability of application prior to a runoff causing rainfall event.
Field experiments were conducted in Platte County, Missouri, during 2006 and 2007 to evaluate PRE, POST, and PRE followed by (fb) POST herbicide programs for the control of glyphosate-resistant ...waterhemp in soybean. All PRE fb POST treatments resulted in at least 66 and 70% control of glyphosate-resistant waterhemp in 2006 and 2007, respectively. Control of glyphosate-resistant waterhemp was less than 23% with lactofen and acifluorfen in 2006, but at least 64% in 2007. Variability in control likely resulted from differences in trial locations and a population of protoporphyrinogen oxidase (PPO)–resistant waterhemp at the Platte County site in 2006 compared with 2007. In both years, glyphosate resulted in less than 23% control of glyphosate-resistant waterhemp and provided the least control of all herbicide programs. Programs containing PRE herbicides resulted in waterhemp densities of less than 5 plants/m2, whereas the POST glyphosate treatment resulted in 38 to 70 plants/m2. Waterhemp seed production was reduced at least 78% in all PRE fb POST programs, from 55 to 71% in POST programs containing lactofen and acifluorfen and by only 21% in the POST glyphosate treatment. Soybean yields corresponded to the level of waterhemp control achieved in both years, with the lowest yields resulting from programs that provided poorest waterhemp control. PRE applications of S-metolachlor plus metribuzin provided one of the highest net incomes in both years and resulted in $271 to $340/ha greater net income than the glyphosate-only treatment. Collectively, the results from these experiments illustrate the effectiveness of PRE herbicides for the control of glyphosate-resistant waterhemp in glyphosate-resistant soybean and the inconsistency of PPO-inhibiting herbicides or PPO-inhibiting herbicide combinations for the control of waterhemp populations with multiple resistance to glyphosate and PPO-inhibiting herbicides. Nomenclature: Acifluorfen; glyphosate; lactofen; metribuzin; S-metolachlor; common waterhemp, Amaranthus rudis Sauer; soybean Glycine max L
PDF
