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1. Credibility of soil Testing- Results os the Iowa Task ForceSeveral factors led to the convening of the Iowa Soil Testing Task Force: (1) The Iowa legislature passed the 1987 Groundwater Protection Act; (2) The Big Spring study in northeast Iowa in a Karst topography region revealed presence of pesticides and nitrates in groundwater; (3) Public awareness of contaminants in public water supplies was enhanced by influential newspapers and other publications; (4) Influential publications did major stories on the results of soil test comparison studies of several... |
2. Certified Crop Adviser (CCA) ProgramThe Certified Crop Adviser (CCA) Program is being developed under the auspices of the American Society of Agronomy (ASA). The ad hoc steering committee is comprised of industry and university agronomists, state dealer associations, independent crop consultants, several organizations (including T.F.1, P.P.I., ARA, TVA) and ASA staff. This is a broad group representing wide geographic parts of the U.S., and has also included USDA officials, representing SCS and Extension. The purpose of the CCA program... |
3. Site-Specific Research in North DakotaSite specific fertilizer application is currently being practiced in the Red River Valley of North Dakota/Minnesota A study has been initiated to determine sampling practices suitable for North Dakota producers using sitespecific farming both within and west of the valley. Two forty acre fields were sampled in 1994 in a 110 ft. grid, separating each sample into 0-6" and 6-24" subsamples. Smaller grid sizes were also obtained at 10 and 2 ft. grid distances in selected areas of each field. Nitrates,... |
4. Grid Sampling or Topography Sampling for Soil NutrientsSite-specific application of fertilizers uses field soil sampling for its information basis. Many fields are currently sampled using a grid approach. In North Dakota, examination of grid sampling showed nitrate-N to follow topographic patterns in a field, allowing the possibility of less intensive sampling for N. Reviewing previous grid sampling work in Illinois, some soil properties may be associated with landscape features, including nitrate-N in the surface 6 inches and soil pH. However, Illinois... |
5. Site-Specific Prediction of Soybean Nitrogen ContributionsSoybean has long been recognized for its nitrogen (N) contributions and yield enhancing effects in crop sequences. Soybean N credits in the Midwest range fiom 20 to 40 Ib of Nlacre (Kurtz et al., 1984). Several Midwestern states recommend a legume credit of 40 Ib of Nlacre following an average crop of soybean. Current Wisconsin recommendations suggest a reduction in nitrogen fertilizer rates for corn following soybean of 1 Ib N hushel of soybean yield up to a maximum credit of 40 Ib Nacre (Kelling... |
6. Spring Wheat Response to Copper Fertilization in North DakotaTraditionally, copper responses have been tllought to be associated with organic soils. However, recent Canadian research has found that copper responses by wheat are possible on low organic matter, coarse textured soils. A yield response to copper in spring wheat was found in North Dakota on a coarse textured, low organic matter soil. Yield responses were not found in similar copper soil test levels of higher organic matter, heavier textured soils. A two-tiered recommendation strategy is suggested... |
7. Soybean Chlorosis in North Dakota- Causes, Severity and Possible SolutionsSoybean acres continue to increase in northwestern Minnesota and North Dakota in spite of severe problems with iron chlorosis in some years. Soybeans often turn yellow within a few weeks of emergence and remain yellow for up to 8 weeks before plants green up and mature. Iron chlorosis tolerant soybeans available today are somewhat effective in reducing chlorotic acreage, but are not tolerant enough to counteract the soil conditions in this area. Several researchers have found that iron chlorosis... |
8. Nitrogen Availability, Time of Release and Movement in RotationsPrevious studies have found that N is released through the decomposition of sugarbeet tops (Moraghan and Smith, 1996: Reitmeier et a]., 1999). There is also evidence that N credits may be justified following other broadleaf crops, such as potato and sunflower. This evidence follows work by Vanotti and Bundy (1995) and Bundy et al. (1 993) suggesting that N credits from annual legumes are provided not by decomposition ofthe roots or release ofN directly into the soil from the roots as some might assume,... |
9. Adjusting N Recommendations Based on a Previously Grown CropNitrogen recommendations in North Dakota are based on a yield goal multiplied from some empirically derived factor in a linear formula. There are a three adjustments to the N recommendations that result form these formulas (Franzen and Cihacek, 1996). They are the soil test nitrate-N to some depth, a sampling date adjustment ifthe sampling was conducted in the fall prior to September 15, and a previous crop credit. Two of these three adjustments are based on some knowledge regarding mineralization... |
10. A Case for the use of Limestone in North DakotaFarmers in North Dakota have long believed that nearly all of the cultivated land in the state was alkaline in pH. A recent survey of the state revealed that between 27% and 50% of the fields tested below pH 7, depending on landscape position, with about 17% of the state with pH less than 6.5. In site-specific studies in fields with dominant pH above 7, nearly all fields contained at least one area with pH below 7. Herbicide carryover studies have shown that areas of even slightly acid pH can result... |
11. A Weighted Classified Method for Nitrogen Zone DelineationEven though zone management in precision agriculture is a relatively new science. extensive research has been conducted on the best predictors for determining optimal nitrogen management zones in site-specific farming (Bausch et al., 2002; Fleming and Buchleiter, 2002; Franzen and Nanna, 2002, Hendrickson and Han, 2000; Lund et al.. 2002: Stenger et a].. 2002). Different techniques. varying from cluster analysis (Jaynes et al.. 2003; Kitchen et al., 2002: Ralston et al.. 2002) to neural networks... |
12. Comparison of Nitrogen Management Zone Delineation MethodsAn alternative to dense grid soil sampling for delineating residual soil N levels or N availability is a zone sampling approach. The zone approach assumes that soil N patterns are logically linked to some inherent causal effect, either natural or man-made. A number of delineation methods have been examined. including apparent soil EC (Kitchen et al.. 1999). yield mapping (Taylor and Whitney. 2001: Diker et al.. 2002), topography (Franzen et al.. 1998), aerial imagery (Williams et al., 2002 Sripada... |
13. Flax Fertility Recommendation Changes in North DakotaFlax has traditionally been grown in North Dakota since early settle~nent by European immigrants. The varieties of flax have been gro~vn for their oil content more than for fiber. Previous recommendations for N and P have becn based on yield goal and soil test level. A review of j~revious research in the region and nctv research on the role of mychorrhizae on P nutrition has resulted in dropping the P recommcndation. Due to the hazard of lodging from over-application of N from unreasonably high... |
14. Residual P Effects on Soybean Yield and Nutrient Removal RatesLong-term experiments were conducted from 1997-2003 on a Nicollet-Webster clay loan soil complex at Waseca, MN to determine the availability of residual P applied for corn on the yield and removal of P by soybeans in the following year. Phosphorus was applied either with the seed at planting as a starter, 5 to 6" deep in a band in the fall, or broadcast and incol-porated by tillage. Tillage systems included no till, strip till, spring field cultivation, and chisel plow plus field cultivation. Tillage... |
15. Zone Delineation for Nitrogen ManagementManaging nitrogen through zone soil sampling has been shown effective in revealing residual soil nitrate patterns in North Dakota. Zone delineation has been constructed using several types of data, including yield maps, remote imagery, topography and soil EC sensor data. A study was conducted in North Dakota, Montana and Minnesota to evaluate zone delineation methods. Across the region, yield frequency maps, topography, remote inlagery and soil EC data were effective in helping to construct zones.... |
16. Field Measurements of Nitrous Oxide Emissions across a Nitrogen Fertilizer Gradient for Corn Cropping SystemsSignificant reductions in nitrous oxide (N 2O) emissions from corn (Zea maize L.) cropping systems may be possible by reducing N fertilizer i nputs with relatively little impact on crop grain yield or economic return. To te st this hypothesis, experiments we re conducted at 4 locations in corn production in Michigan in 2007. All sites were under a corn-soybean rotation. Prior to planting, six rates of urea fertilizer (0-200 lb ac -1) were broadcast and incorporated into four replicate plots (RCBD)... |
17. Nitrogen Recalibration for Wheat in North DakotaThe general formula for determining N fertilizer ra te in North Dakota for about thirty-five years has been N-rate = (2.5 X Yield Potential (or Yield G oal) less credits from previous crops and soil test nitrate-N from a 2-foot soil core composite. Historically high fertilizer N costs and the ability to fertilize within fiel ds rather than whole field N management has resulted in a reexamination of N calibration data, and an effort to expand the modern N calibration database with new field experiments.... |
18. Nitrogen Recalibration for Wheat in North DakotaThe rise in grain prices and fertilizer costs, as well as the need for more soil-specific recommendations has spurred recent research into N response of wheat in North Dakota. Combining data from 1970 to 1990, together with recent studies has shown that new recommendations are in order. There is a rela tionship of wheat yield to available N. The relationship is better when residual soil nitrate is considered. Different areas of the state partition out with different response curves. Using the 'return... |
19. Use Of Corn Height To Improve The Relationship Between Active Optical Sensor Readings And Yield EstimatesPre-season and early in-season loss of N continues to be a problem in corn (Zea mays, L.). One method to improve nitrogen use efficiency is to fertilize based on in-season crop foliage sensors. The objective of this study was to evaluate two different ground-based, active-optical sensors and explore the use of corn height with sensor readings for improved relationship with corn yield. Two different ground-based active-optical sensors (Greenseeker�, Trimble, Sunnydale, CA; and Holland Crop Circle... |
20. Continuous Corn Production As Affected By Starter Fertilizers Containing Nitrogen, Phosphorus, and SulfurCrop rotations in the Midwest have changed from the traditional corn-soybean rotation to more corn-intensive rotations. Due to the expanding demand for corn to supply the ethanol industry and the increasing insect and disease challenges facing soybean producers, some farmers are switching to a corn-corn-soybean rotation or for some, continuous corn. These rotations produce large amounts of biomass (corn stover) that often remain on the soil surface with present day tillage systems. This is good... |
21. Nitrogen Rate Revisions for Corn in North DakotaNitrogen rates in North Dakota have been based on a yield-goal or yield-potential formula for over forty years. The currently published formula (Franzen, 2010) is: Recommended N rate = (Yield Potential, bushels per acre) X 1.2 less N credits from previous crops and soil test nitrate to 2 feet in depth. A yield-based strategy was practical when N costs were relatively low and yields in North Dakota were at most 100 bushels per acre. However, due to improved germplasm developed at North Dakota State... |
22. Can Soil Information Better Inform Canopy Sensor Algorithms for Corn?Corn production is often limited by the loss of nitrogen (N) due to leaching, volatilization and denitrification. The use of canopy sensors for making in-season N fertilizer applications has been proven effective in matching plant N requirements with periods of rapid N uptake (V7-V11), reducing the amount of N lost to these processes. However, N recommendation algorithms used in conjunction with canopy sensor measurements have not proven accurate in many fields of the U.S. Cornbelt, resulting in... , N.R. Kitchen, J. Camberato, P.R. Carter, R.B. Ferguson, F.G. Fernandez, D.W. Franzen, F.G. Fernandez, E.D. Nafziger, C.J. Ransom, , J. Shanahan, G.M. Bean |
23. Soybean and Corn Yield Response to Fertilizar Placement and Tillage SystemNutrient availability and, consequently, yields can be strongly influenced by tillage system and fertilizer placement. Also, different genotypes and rooting systems can affect nutrient uptake and plant growth. The objective of this study was to evaluate fertilizer placement and tillage system effects on yields in soybean and corn with different varieties/hybrids. The experiment was established in two locations in Kansas and the experimental design was a randomized complete block with a split-plot.... |
24. Nitrogen and Phosphorus Recalibration for Sunflower in the Northern Great PlainsSunflower producers in the northern Great Plains states of North Dakota, South Dakota, and Minnesota are presently directed to N and P recommendations that originate from research performed in the late 1960s and early 1970s. These three states alone produce more than 80% of the sunflowers in the United States on a yearly basis (USDA-NASS, 2015). The current general formulas determining N and P fertilizer rate in these top-producing states are equivalent. The N recommendation is represented here by... |
25. North Dakota Corn Recommendations for Preplant and Sensor Directed Sidedress NNitrogen rates for preplant N application in North Dakota have been drastically revised. The former yield-based strategy may have served when N costs were stable and relatively low and high yields in North Dakota were rarely higher than 100 bushels per acre. Due to improved germplasm developed at North Dakota State University and other northern Land-Grant Universities with favorable adaptation to North Dakota climate and soil conditions corn has become one of the most planted crops in the state.... |
26. Variability of Soil Test Potassium in Space and TimePotassium soil test may be highly variable within fields. In the western part of the North Central Region, where the history of K fert ilization is marked by low rates of K fertilizer and fields where K has never been applie d, natural variability of K is governed by clay content and landscape position. In areas where K fertilization has been high, man-made variability is more common. Man-made variability may be experienced as differences in historic rates within fields merged over years of ownership... |
27. Slow-Release Nitrogen Fertilizers and Nitrogen Additives for Field CropsNitrogen management continues to be difficult due to transformations of nitrogen fertilizers that are possible when applied to soil and the uncertainties of weather (Cabrera et al., 2008). Nitrogen fertilizer in the form of urea is subject to ammonia volatilization through the activity of the urease enzyme found ubiquitously in soil (Kissel et al., 2008). Nitrate fertilizer is subject to leaching (Randall et al., 2008) or denitrification (Coyne, 2008) depending on the water content of the soil and... |
28. Interaction of Soil Applied Herbicides with Soil pHManagement of soil pH is important in enhancing the availability of certain plant nutrients and in minimizing toxic levels of other elements to crops. However, the reaction of herbicides with soils under varying soil pH levels can affect both crop growth and herbicide performance. Soil pH affects herbicide performance in several ways. When crops are under stress due to nutrient imbalance from unfavorable soil pH levels, application of certain herbicides may increase risk of crop injury. When soil... |
29. Methods and Limitations of Zone Sampling Using Topography as a Logical BasisTwo forty-acre fields in North Dakota were sampled in a 110 foot grid. Each field was measured for elevation in the same 110 foot grid. Topographic sampling zones were identified in each field and a correlation of the sampling based on these zones was compared to the correlation values from a 220 foot grid. Nitrate-N and the 220 foot grid were both correlated to the 110 foot sampling values for nitrate-N and P. A map of field nitrate-N levels from topography sampling compared to the 220 foot grid... |
30. Lessons learned from long-term P & K trialThis presentation will disucss corn and soybean response to P and K over 10 years in a notill system. ... C.A. Laboski, T.W. Andraski |
31. Manure Total Nitrogen Variability Due to Analytical Method and Total Solids ContentKnowing the nutrient analysis of a fertilizer source is essential to ensure adequate nutrients for crop growth, while not causing potential environmental impacts by overapplying nutrients. Using manure as a nutrient source can complicate matters as the nutrient content can be variable and the manure can come in a range of liquid to solid consistencies. There are multiple laboratory methods to determine different nutrient parameters and for manure total nitrogen levels the most common methods... N.L. Bohl bormann, M.L. Wilson, E.L. Cortus, J. Floren, R.O. Miller, L. Gunderson |
32. Biochemical Soil Health Indicators Related to Economic Optimum Nitrogen Rate in CornIn corn production, nitrogen (N) fertilization is one of the main inputs to enhance yield. However, in the last few years, reducing N utilization has been a goal due to environmental concerns and production costs. Soil health tests have been studied to understand the relationship with N availability and its use to adjust N recommendation rates. The objective of this study was to evaluate the relationship of different soil tests with the economic optimum N rate (N) for corn in Wisconsin. Soil samples... D. Orjuela diaz, C.A. Laboski, F. Arriaga |
33. Employing Statistical Models to Determine the Soil Tests and/or Soil Characteristics That Improved EONR Prediction in CornIn corn production, nitrogen (N) fertilization is crucial for increasing yield. However, in the last few years, there has been a push to use less N due to environmental concerns and production costs. There has been an interest in using soil health tests to predict N mineralization potential and further understand soil N availability to adjust N recommendation rates. Different statistical models like regression or decision tree analysis have been used to determine how the Economic Optimum N Rate... D. Orjuela diaz, C.A. Laboski, F. Arriaga |
34. Investigating Soybean Response to Phosphorus with a Cover Crop and Fertilizer Combination in KansasThe soybean crop provides one of the best opportunities to include a cool season cover crop (CC) ahead of planting. This study aims to maximize phosphorus (P) use efficiency by the soybean crop by using CC planting as a window of opportunity for better P fertilizer placement and timing. Specifically, combining P fertilizer with cereal CC seeds will place the fertilizer below the soil surface and combine two operations (CC planting and fertilizer application) in one pass. Other benefits include... J. Demarco, D. Ruiz diaz |
35. A Direct Approach to Measure Cover Crop Nitrogen Uptake from Dairy Manure Via 15N EnrichmentFall manure applications are a standard practice across Wisconsin, primarily due to manure storage constraints and unpredictable spring field conditions. Unfortunately, manure derived nitrogen (N) is at risk for runoff and leaching into groundwater without an appropriate mechanism for N retention. Fall-planted grass cover crops can serve as N scavengers, reducing losses of manure N to the environment, especially post-silage harvest, however potential tradeoffs between sufficient N uptake and spring... T. Judd, M. Ruark, Z. Freedman |
36. Soybean Response to Phosphorus Fertilizer and Cover Crop Combination in KansasPhosphorus (P) plays a critical role in supporting plant growth and maximizing crop yields, but its availability is often limited in agricultural soils. Cover crops (CC), widely used to improve soil health, can also influence nutrient availability and moisture dynamics. This study investigates the effects of P fertilization and CC on soybean P uptake, soil moisture, and grain yield in Kansas. Field trials were conducted across multiple sites in 2022 and 2023, using a randomized complete block... J. Demarco, D. Ruiz diaz |