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1. A Brief History of the Great Plains Soil Fertility ConferenceThe Great Plains Soil Fertility Conference began in 1980 as the Great Plains Soil Fertility Workshop at the Denver Sheraton Hotel on Quebec in Denver, CO. This Workshop was patterned off the successful North Central Extension Industry Soil Fertility Workshop which had been in existence since 1971. Several companies provided some initial funding to get the project off and running. The objectives of the Workshop/Conference were to bring together researchers and i... L. Murphy |
2. Banded P Placement for Sugarbeets in Calcareous SoilPhosphorus (P) is an essential element for sugarbeet (Beta vulgaris) nutrition. Soils in the Western US tend to be calcareous and alkaline, resulting in low P solubility. Sugarbeets have difficulty exploiting soluble P in surface soil due to its tap root system. Research in the North- Central US supports P applied in a band in contact with the seed or below the seed for best results. However, grower concerns about germination problems and seedling vigor have prevented adaptation of these tech... B. Hopkins, J. Ellsworth |
3. Banding 10-34-0 on Sugar BeetsField experiments were conducted over 10 site-years in the Red River Valley of Minnesota on various soil types that tested low in available P. The objectives were to evaluate sugar beet yield response to liquid 10-34-0 and dry 11-52-0 fertilizer banded in-furrow with the seed at planting and to compare those responses to that of phosphorus (P) fertilizer rates broadcast and incorporated prior to planting. Treatments had no effect on net sucrose concentration in the root ... A. Sims, L. Smith |
4. Carbon Budget in Dryland Agroecosystems After 12 Years in No-till As Affected by Climate Gradient, Slope Position, and Cropping IntensityBecause available soil water is the most limiting factor in dryland cropping systems in the central Great Plains, summer fallow was implemented to stabilize production by storing two years of soil water for one year’s crop. The traditional dryland cropping system consists of conventional tillage management of a crop-fallow rotation which produced one crop every two years. In order for the fallow period to successfully store soil water, weeds and volunteer plants ne... L. Sherrod, G. Peterson, D. Westfall, L. Ahuja |
5. Chloride Fertility: Small Grain Variety and Disease ResponsesFor spring wheat (Triticum aestivum L.), chloride fertilizer added to low chloride-testing soil results in a positive yield gain 70 % of the time. Some, but not all, of these yield responses have been attributed to chloride interaction with disease susceptibility. Because soil fertility and disease suppression are among the most important management tools used by farmers, additional research on the interaction between chloride fertility and disease suppression is ne... W. Riedell, L. Osborne, S. Osborne |
6. Chloride Response of Corn and Grain SorghumResearch in several states in the United States and in Canada has documented positive small grain responses to chloride (Cl) fertilization, yet little research has been done on corn or grain sorghum. Field research was conducted in Kansas evaluating Cl fertilization on corn and grain sorghum. Chloride rates and sources were evaluated at several farmer-cooperator sites. Corn and grain sorghum yields were consistently increased with Cl fertilization when soil Cl... R. Lamond, K. Rector, C. Godsey, L. Ferdinand |
7. Comparison of Annual and Multi-year N-based and P-based Manure ApplicationsThis 4-yr study (2000-2003) compares beef manure application strategies in their impact on soil and plant nutrient concentrations and nutrient runoff and leaching. The treatments were a fertilizer control, annual N-based manure application, N-based applied every other year, annual P-based, P-based applied every other year, and P-based applied once every four years. By the third year of the study, soil test P levels in the soil surface reflected the amount of P2O5applied ... J. Davis, C. Truman, K. Iversen, K. Doesken |
8. Comparison of Multi-spectral Analog and Imaging Systems for Assessing Plant Nitrogen Status in Irrigated CornUniform applications of nitrogen (N) across a field may result in over fertilization in some areas as well as under fertilization in others. Farmers, consultants, and other end users need rapid, robust techniques to spatially and temporally assess a crop’s N status in order to apply N “as needed” and “where needed”. The objective of this research was to compare the differences in response of a radiometer system and an imaging system for asse... W. Bausch |
9. Developing, Delineating, and Managing Production Level Nutrient Management ZonesGrid soil sampling has been used to develop nutrient maps to guide precision fertilizer applications since the inception of precision agriculture. However, the cost and labor associated with collection and analysis of soil samples to accurately describe spatial properties of fields can be prohibitive for most agronomic crops. As a result of these limitations, much interest is now being directed to the use of production level “management zones” (MZ) to allow i... W. Gangloff, D. Westfall, R. Khosla, T. Shaver, H. Farahani |
10. Development and Use of the Soil Management Assessment FrameworkSoils perform a number of critical functions essential to productivity and environmental quality. Management practices affect these soil functions. However, spatial and temporal variation and the slow rate of change in many soil properties make it difficult to assess the effects of management on soil functions. Tools are needed to assist managers in making assessments of the effect their management practices are having on the soil resource. The Soil... B. Wienhold, S. Andrews |
11. Dissolution of Granular Fertilizers and Diffusion/lability of P from Fluid and Granular Fertilizers in Alkaline and Calcareous Soils of Southern AustraliaUnlike many soils in Europe and North America, many Australian soils are still responsive to additions of P fertilizer, especially alkaline and/or calcareous soils that dominate the low rainfall zone of southern Australia. Poor responses to granular fertilizers in these areas have recently stimulated a swing by grain growers towards the use of fluid formulations, often resulting in significant yield responses. Laboratory experiments examining P diffusion were undertaken ... E. Lombi, M. Mclaughlin, C. Johnston, T. Mcbeath, S. Stacey, R. Armstrong, R. Holloway |
12. Economics of Variable-rate N Management on CornOver the past several years’ growers have begun to adopt and implement the use of precision farming technologies. Growers and practicing consultants continue to question the profitability of this technology. No data currently exists in the Western Great Plains region demonstrating the economic feasibility of precision farming technology. The objective of this study was to assess the economics of uniform versus variable-rate nitrogen (N) fertilizer applic... R. Khosla, B. Koch, D. Westfall, M. Frasier |
13. Effect of Nitrogen Rate and Timing of Application on Stockpiled BermudagrassFeeding hay through the winter contributes a large portion of the costs associated with cow-calf production. Forage management strategies to lengthen the grazing season and reduce hay consumption would be beneficial in increasing profitability. Stockpiling bermudagrass for livestock consumption in late fall and winter has not been thoroughly evaluated in southern Oklahoma. This study was initiated at Burneyville, Oklahoma in 2000 to determine the effect of N rate and timing of appl... J. Ball, W. Thomason, F. Motal, S. Norton |
14. Effect of Phosphorus Rates on Bermudagrass Yields in Three Southern Oklahoma Locations in 2002-2003Small plot research tests were established on cooperating farmers’ fields in three south central Oklahoma locations in 2002 and continued in 2003. These included a Weatherford soil testing low in extractable P (Mehlich 3), a Port soil testing low in P and a Lela soil testing high in P. Rates of applied P fertilizer were 0, 25, 50, 75, 100 and 200 lbs of P2O5per acre. There were 4 replications of each rate. All plots received 200 lbs N and 120 ... E. Funderburg, D. Annis |
15. Effect of Starter Nitrogen Fertilizer on Nitrogen Fixation of Soybeans in the Northern Great PlainsEnvironmental conditions at the time soybeans (Glycine max (L.) Merrill) are planted in the northern Great Plains are such that nitrogen (N) fixation may not occur immediately, therefore additions of N as starter fertilizer may increase initial growth of soybeans and possibly increase yield and quality. The objective of this study was to evaluate the response of soybeans to low rates of N applied at planting. A field experiment was established within a two-year corn... S. Osborne, W. Riedell |
16. Fertility Management for the Pulse-based Cropping Systems in the Semiarid Northern Great PlainsAnnual crop production of the semiarid Northern Great Plains has historically been dominated by cereals, chiefly spring wheat (Triticum aestivum L.) and durum wheat (Triticum turgidum var durum). Low prices for cereal grains, coupled with increasing production problems in wheat- based monoculture systems, are encouraging producers to seek alternative to cereals. In the past two decades, the area devoted to production of annual pulse crops has increased significantly in the semi... Y. Gan, B. Mcconkey, G. Clayton, G. Lafond, F. Walley |
17. Fertilizer Management for Strip-till and No-till Corn ProductionStrip-tillage for corn production can be advantageous over no-till, particularly in areas with heavy soils and high rainfall during spring months. Under these conditions in no-till systems, planting delays and/or slow, uneven emergence are common. Strip-tillage creates a narrow tilled area for the seedbed while maintaining the inter-row residue cover, allowing for erosion protection associated with no-till, yet providing an area in the row where the soil will dry out and... L. Ferdinand, R. Lamond, B. Gordon, K. Janssen, C. Godsey |
18. Functional Significance of Glomalin to Soil FertilityIn the U.S., soil is lost to wind and water erosion at a rate of nearly 2 billion tons yr-1. The formation of aggregates helps stabilize soil and increase soil fertility and water relationships. Organic matter concentration is correlated with the percentage of water-stable aggregates (WSA). The hypothesis of this study was that glomalin, a glycoproteinaceous substance produced by arbuscular mycorrhizal fungi, would be a major fraction of organic C in WSA. Four... K. Nichols, S. Wright, M. Liebig, J. Pikul jr. |
19. Harvest Grain and Crop Residue Yield Differences in Crop Rotation and Residue Management Systems in Tillage Transition in Eastern South DakotaA long-term field study was established in Brookings, SD to investigate the impact of crop rotation, tillage, and residue management on grain yield and crop residue production. These results were compiled when this field was undergoing a transition in the influence of two contrasting tillage systems in the first four years of the study. Initial soil test results indicated that the organic matter levels and pH as well as extractable K and orthophosphate-P (0-6") were high. ... H. Woodard, A. Bly |
20. Impact of Diversified Rotation on Corn N Uptake, Yield, and Soil QualityIncreased length of rotation and increased crop diversity may improve efficiency of water and nitrogen (N) use by corn (Zea mays L.) and soil quality. Objectives were to determine the effect of diversified crop rotation on: 1) N-fertilizer use efficiency (NUE) of corn, 2) water use efficiency (WUE) of corn, and 3) temporal change in soil quality attributes. An experiment was started in 1997 on a Barnes clay loam (fine-loamy, mixed, superactive, frigid Calcic Hapludo... J. Pikul jr. |
21. Innovative Corn and Soybean Production Systems for the Great PlainsIn an eight-year study of twin row planting, our intentions were to see if additional spacing per plant would allow more ear flex and more cubic foot of soil mass per plant. In the first five years of study, over 5000 acres were planted, in five states. In each of those five years, we continually added new and upgraded agronomic facts that we held to be true, i.e. PPI work on deeper P placement, Dr. Barnie Gordons work on high N starters, split applications and precisional placemen... |
22. Irrigated Corn Response to Nitrogen Fertilization in the Colorado Arkansas ValleyHigh levels of residual NO3-N are present in the soils in the Arkansas River Valley where alfalfa, grains, and vegetable crops are produced. Nitrogen requirements to optimize yield potential of crops, such as corn, following vegetables needs to be evaluated to reduce NO3-N leaching potential in the Valley where high NO3-N levels have been reported in the ground water. The effects of N source (urea and Polyon®3) and fertilizer N rate on corn yields were evaluated for 4 years.&nb... A. Halvorson, F. Schweeissing, M. Bartolo, C. Reule |
23. Is There a Need to Provide N and S to Canola in Any Given Ratio?The importance of N and S nutrition of canola is well recognized (Janzen and Bettany 1984; Bailey 1986; Grant and Bailey 1993; Jackson 2000; Malhi and Leach 2002). Agronomists today are recommending that a N:S ratio of between 5:1 and 7:1 is adhered to when fertilizer N and S are applied. This is also reflected in the provincial recommendations. Thus, Alberta Agriculture, Food and Rural Development (2001) point out that optimum canola requires an N:S ratio of ... R. Karamanos, T. Boon goh, D. Poisson |
24. Kansas State University Fertilizer Recommendation RevisionsSoil testing has long been recognized as the cornerstone for developing cost effective, efficient and environmentally sound nutrient management programs. However, there are still many acres that do not have a sound soil test history. This indicates that there is still much education needed to increase farmer acceptance of soil testing in developing agronomically sound and profitable nutrient management programs. At the same time, USDA is placing increased emph... D. Leikam, R. Lamond, D. Mengel |
25. Management Effects on Maturity, Seed Yield, and N2-fixation in Dry BeanThe association between dry beans (Phaseolus vulgaris L) and its associated Rhizobium symbiont (R. phaseoli) has been shown to be inefficient and as such, unable to provide adequate N for maximum bean production. Fertilization with inorganic N is sometimes recommended, but disadvantages of adding fertilizer N include delayed maturity and possible inhibition of N2 fixation. It is unknown whether N fertilizer applications are most beneficial during early growth s... K. Maxwell, B. Stevens |
26. Management of High Yielding Canola CultivarsYield potential of new canola varieties is much higher than older ones, raising questions about whether current management recommendations are adequate to ensure optimum yield. One question that arises is whether such varieties require greater inputs of fertilizer nutrients, particularly nitrogen (N), to realize optimum economic returns. We initiated a three level factorial experiment to investigate the impact of 3 seeding rates, 3 target fertility levels and a fungicide... S. Brandt, D. Ulrich, G. Lafond, R. Kutcher, S. Malhi, A. Johnston |
27. Managing Drought Risk with Post-emergent N Appliactions in Spring Wheat and CanolaFertilizer nitrogen accounts for the largest portion of total fertilizer costs. Unlike other nutrients like P and K, nitrogen is more prone to losses from leaching, nitrous oxide emission and denitrification. Producers are interested in more effective ways of managing the risks associated with N management, especially in the drier areas of the Canadian Prairies. Two separate studies were conducted. The first one examined the feasibility of post-emer... G. Lafond, S. Brandt, A. Johnston, W. May |
28. Managing Soil Acidity in Continous No-tillRecently, management of acidic soils in no-till cropping systems has become an important issue with increasing acreages of no-till and continued surface application of nitrogen fertilizer. Our objectives were to identify vertical movement of surface applied lime, determine the most effective type of lime in changing soil pH, and determine the correct application rate of lime for no-till soils. Two sites were selected for small-plot studies in south-central Kansas in 2000... C. Godsey, R. Lamond, L. Ferdinand |
29. Next Generation Application TechnologyNew technologies and new applications of new and existing technologies continue to be integrated into equipment for the application of crop production inputs including fertilizer, pesticides and seed. GPS assisted steering now allows “hands off” steering of self-propelled applicators and tractors. Results include better application accuracy, improved machine efficiency and less operator fatigue. Variable rate liquid systems are available to compete... N. Wollenhaupt |
30. Nitrogen and Crop Management Influence Irrigated Corn Yields and Greenhouse Gas EmissionsThe influence of tillage system and N fertility on corn grain yields, residue C inputs to the soil, soil organic carbon (SOC) sequestration, NO3-N leaching potential, and greenhouse gas emissions under irrigated continuous corn production was evaluated. Corn was produced on a Fort Collins clay loam using no-till (NT) and conventional-till (CT) systems at several N fertility levels. Soil and plant data have been collected since the spring of 1999. Corn grain yi... A. Halvorson, A. Mosier, C. Reule |
31. Nodulation and Yield Responses to “Starter” N and P in Field Pea, Lentil, and Chickpea in the Semiarid Northern Great PlainsGrain legumes require a high level of N fertility to achieve maximum yield and protein (Sosulski et al., 1974; Sosulski and Buchan, 1978). In these 1970’s and 1980’s studies, nodulation and nitrogenase activity were generally poor even when the legumes were inoculated with rhizobia (Sosulski and Buchan, 1978). Although indigenous populations of rhizobia are often present in the soils, they might be ineffective for inducing N2 fixation under semiarid environments (Kucey and Hy... Y. Gan, G. Clayton, G. Lafond, F. Walley, B. Mcconkey |
32. Nutrient Management in Cotton-sorghum Vs. Continuous Cotton RotationsThis study seeks to provide information to High Plains producers on soil fertility requirements for cotton grown in rotation with sorghum. The benefits of rotation on yields and soil properties are also being studied. It is known that the practice of crop rotation benefits the soil and crops from the standpoint of soil fertility, pests, and diseases. In this project we tested cotton-cotton and cotton-sorghum rotations. Within these cropping systems ... K. Bronson, J. Booker, W. Keeling, C. Trostle |
33. Phosphorus Fertilizer Effects on Forage, Beef and Grain Production from Winter WheatPhosphorus fertilizer was surface applied or injected in a NPS solution and compared to a surface-applied NS solution to determine if fall forage production could be increased by P applications and to determine if the additional forage could be captured through beef production to make the P applications profitable. The experimental units were nine 25-acre pastures in which the three treatments were replicated three times and grazed with yearling stocker calves in two management sys... D. Robinson, J. Sij, W. Pinchak, R. Gill, S. Bevers, D. Mallinowski, T. Baughman |
34. Plant Availability of Phosphorus in Swine Slurry and Cattle Feedlot ManureTo utilize manure phosphorus (P) for crop production, the amount of P that is mineralized and subsequently becomes plant available needs to be determined. A laboratory incubation study was conducted to determine P release and availability from applied swine and cattle feedlot manure in three soils. Treatments included incubation temperature (11, 18, 25, and 32 oC), P source (swine and beef cattle feedlot manure, synthetic fertilizer, and no manure or fertilizer), wa... B. Eghball, B. Wienhold, B. Woodbury, R. Eigenberg |
35. Point Vs. Area Grid Soil Sampling in the Great PlainsTraditionally, soil sampling has relied on the approach of collecting multiple cores (or sub-samples) from the entire area of interest (e.g., a field), and then combining them into a single soil sample for analyses. Samples were collected from throughout the area with recognition that soil fertility varied spatially. Where greater spatial variability was anticipated, size of sampling area usually was reduced to provide a better estimate of soil fertility. Unfo... T. Kastens, K. Dhuyvetter, J. Schmidt |
36. Positional Availability of Phosphorus from Surface Fertilizer BandsOur objective in this field study was to determine the relative distribution of P applied as a liquid starter fertilizer in a surface band during the early part of the corn growing season. Research was conducted during three years (2001-2003) at three locations in central Iowa. Exchange-resin membranes were used to characterize P movement. Treatments consisted of a control and 15-30-10 or 60-30-10 starter dribbled (30 gal./A) on the soil surface two inche... J. Kovar, P. Schroeder, K. Washburn |
37. Potassium Fertilization of Corn in Reduced Tillage Production SystemsPotassium (K) deficiency can be a problem on soils that have been managed with reduced tillage practices. The large amount of residue left on the soil surface can depress soil temperature and interfere with plant growth, nutrient uptake, and ultimately grain yield. Soil temperature influences both K up-take by root and K diffusion through the soil. The appearance of K deficiency in fields managed with conservation tillage systems has been reported with greater frequency in resent y... B. Gordon |
38. Quantifying Nitrate Leaching in Sandy Soils As Affected by N and Water ManagementEfficient use of nitrogen (N) fertilizer for corn production is important for maximizing economic return and minimizing NO3 leaching to groundwater, especially on irrigated, sandy soils. The objectives of this study were to quantify the NO3leaching for a sandy soil typical of Kansas’ tributaries, under current and alternative N and water management strategies for irrigated corn. Six fields were selected in 2001 and 2002 along the Republican (1), Kansas (2), and... R. Gehl, J. Schmidt, L. Stone, L. Maddux |
39. Rapid Removal of Subsoil N by Conventional and Non-N-fixing AlfalfaNitrate contamination of groundwater is an increasingly serious health issue in the Central High Plains. Although better water and fertilizer management techniques have reduced the rate of leaching from many irrigated fields, high concentrations of residual nitrate accumulating are still observed just below the root zone of irrigated row crops, particularly in fields with a history of animal waste application. Alfalfa (Medicago sativa L.) may be the ideal crop for r... T. Willson |
40. Real-time, In-season Nitrogen Application Using Optical SensorsVariable rate application of fertilizer materials for cereal crop production has been an intense area of research for the last several years. Non-destructive methods of plant analysis, namely crop reflectance based vegetative indices, have been evaluated and researched to determine which provides the best in-season information to make fertilizer recommendations. Because nitrogen (N) fertilizer is typically the largest seasonal crop input (with the exception of water, if ... R. Mullen, W. Raun, G. Johnson, M. Stone, J. Solie, K. Freeman |
41. Safening Seed Placed Urea with Agrotain®The introduction of no-till and direct seeding in the western Canadian prairies has necessitated placing urea N fertilizer with the seed in the majority of cases. Plant stand reduction due to seed-placement of high rates of urea N fertilizers is attributed to the toxic effects of ammonia/ammonium. Current guidelines for seed-row placement of nitrogen in general and urea in particular to avert seedling damage are based on seedbed utilization, soil texture (Saskatchewan Ag... R. Karamanos, J. Harapiak |
42. Satellite Imagery for Small Plot Research and Precision Farming - Nitrogen Relationships in Irrigated CornHigh quality satellite imagery that recently became available may be useful for predicting the N status of crops, need for additional N fertilization, and crop yield potential. Our objective was to determine if the high-resolution digital images from the QuickBird™ satellite launched in late 2001 had potential in predicting irrigated corn biomass and grain yields and available N at planting as indicated by leaf color on 27 July 2002 from conventional till and no-till research... J. Cipra, A. Halvorson |
43. Soil Nitrogen Dynamics from Various Legume Crops Used for Fertiliy in Organic Fruit ProductionThe increasing cost of importing animal manures for organic fruit orchard fertility has forced growers to seek alternative sources of organic nutrient inputs. The objective of this study was to evaluate the nitrogen (N) dynamics of several on-farm N sources as a viable supply of organic N fertilizer. The timing of N mineralization is also critical to achieving good fruit production. Four year old organic Suncrest peach trees were used for this study. &nbs... R. Godin, S. Ela, K. Schultz |
44. Soil Test P and P Source Impacts on P Runoff from Calcareous SoilsLong-term application of phosphorus (P) to soils at rates in excess of crop uptake can result in elevated soil P levels (Snyder et al., 1993), which previous research has shown directly influences the amount of P in runoff (Sharpley et al., 1977, 1978, 1995; Daniel et al., 1994; Pote et al., 1996). Because soil test and runoff P concentrations are related, excessive soil P levels may result in significantly high runoff P levels, which accelerate surface-water eutrophication. ... A. Elliott, R. Schierer, J. Davis, R. Waskom, A. Schlegel |
45. Strategies for Maximizing Crop Recovery of Nutrients Applied As Liquid Swine ManureSince the demise in 1996 of the freight rate subsidy for transport of grains by rail from Western Canada to port, there have been increased efforts to develop a local livestock industry to utilize feed grains produced in Saskatchewan and other prairie provinces. This has led to an expansion in the number of intensive livestock operations, particularly swine production systems, on the Canadian prairies. The desire to develop responsible manure management strategies in con... J. Schoenau, S. Mooleki, S. Malhi, G. Hultgreen |
46. The Effect of Low Rates of Commercial Humic Acid on P Availability and Spring Wheat YieldHumic acid (HA), a soluble fraction of humus, has been found to increase crop yields under certain conditions, possibly due to increased nutrient availability. A study was conducted to determine the effects of low rates of commercial HA on P availability and spring wheat yields in both a calcareous soil and non-calcareous soil. In Phase I, soluble P concentrations were monitored at 0.75, 1.5, and 2.25 in. from a MAP band that had either been coated with 1.5 lb HA/ac or l... C. Jones, J. Jacobsen, A. Mungaas |
47. The Future Role of USDA NRCS in Nutrient ManagementSince 1999 USDA Natural Resources Conservation Service has integrated nutrient management planning into the producer’s over-all conservation plan. A nutrient management plan contains the guidance for nutrient rate, form, timing, and method of application. Each action is based on specific local climate, soil, crop, and management conditions. The intent is to improve water quality, as well as soil, plant, air, and animal quality conditions, both on and off... J. Lemunyon |
48. The Role of P Fertility and Mycorrhizae in Flax ProductionEnsuring adequate P nutrition in flax is difficult, because flax is sensitive to seed-placed P and may be less efficient than many crops at using fertilizer P. Studies conducted for three years at two locations in western Manitoba indicated that flax seed yield, mycorrhizal association and Cd concentration were primarily influenced by preceding crop. Early-season P nutrition was enhanced by residual P and by side-banded P fertilizer, but effects on final seed yield ... C. Grant, M. Monreal, B. Irvine, D. Mclaren, R. Mohr |
49. Urea Application Timing Influence on No-till CornFertilizer N for no-till corn in South Dakota is often limited to surface applications of urea. Surface applied urea can volatilize. A study was conducted in 1998, 1999, 2000 and 2002 (four site years) on no-till corn comparing surface broadcast urea timing. Nitrogen rates (50 and 100 lbs N/a) were applied in the fall, winter, early spring, planting, and V-6 stage. Ear leaf samples were analyzed for N concentration in 1999 and 2000 and grain yield was measured each year. Precipitation was mea... R. Gelderman, J. Gerwing, A. Bly |
50. Use of a Crop Canopy Reflectance Sensor for In-season N Management of CornOver-application of nitrogen (N) fertilizer on corn has resulted in elevated levels of N in ground and surface waters. A major factor contributing to decreased N use efficiency and environmental contamination for traditional corn N management schemes is routine pre-season application of large doses of N before the crop can effectively utilize this N. Our long-term research goal is to reduce these over-applications by using remote sensing to direct fertilizer only to areas need... J. Shanahan, J. Schepers, D. Francis, R. Caldwell |