Proceedings
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1. A Comparison of Point Injected and Knifed Phosphorus for Winter WheatThere are almost 2 million acres of winter wheat grown in South Dakota. Most is produced in the southwest part of the state on residual clay soils in a wheat fallow rotation with only limited, shallow sweep tillage. Very reduced tillage is necessary for wind and water erosion control, and water conservation on the long steep slopes. The continued use of shallow tillage on highly buffered, high pH soils has made broadcast phosphorus fertilizer inefficient in increasing wheat yields, even though p... |
2. A Field Study of Soil Test Variability, Its Effects on Accuracy of Fertilizer Recommendations, and the Subsequent Effect of Variable Rate Fertilizer Application on Soil Test ValuesThree 2.5 acre blocks were selected for intensive soil sampling from within an approximate 90 acre field which had been partitioned into 35, 2.5 acre blocks by a farm supply dealer. The 2.5 acre blocks had previously been sampled on a central composite grid basis and a variable rate fertilizer spreader (VRS) programmed for fertilizing the field. Three other more intensive sampling techniques were used to sample the 3 blocks selected for more detailed studies. Results obtained showed that soil te... |
3. Alfalfa Response to K Rate, Source and Time of ApplicationThe potassium (K) requirement of alfalfa is greater than that for any other nutrient. Potassium influences several systems within-alfalfa plants, including enzyme activity, carbohydrate production and transport, stomata1 activity: photosynthesis through chlorophyll content and CO, exchange rate, and nitrogen fixation (Munson, 1985). Potassium also markedly influences alfalfa agronomically through yield increases and improvements in forage quality, disease resistance, and overwinter survival. A s... |
4. Ammonium Thiosulfate Effects on Corn ProductionAmmonium thiosulfate ((NH,),S,O,, ATS) and urea-ammonium nitrate solution (UAN) were applied in different combinations to corn grown in five site-year studies to assess any effects of ATS on corn performance. Ammonium sulfate ((NH4),S04, AS) was included in three of these comparisons as an alternate sulfur (S) treatment. Adding ATS to UAN increased corn yield in one comparison, decreased it in another and had no effect on yield in others. Adding AS had no effect on corn yield. Neither S material... |
5. An Evaluation of Methods for Determining Site-Specific Management ZonesNumerous procedures have been examined for identifymg management areas within fields. Traditional soil surveys give a general understanding of the effects soil mapping units have on crop productivity. In the USA. county soil surveys report the average grain yield of major crops by soil series. Slope position and landform are topographic features thal also have been used to explain water and crop productivity relationships (Mulla et al., 1992; Sudduth et al., 1997). Generally, footslope positions... |
6. Banded Potassium for Ridge-till Planting SystemsThe ridge-till planting system is a proven tool for controlling soil erosion and providing maximum efficiency of water use by corn. The use of the ridge-till planting system in the northern Corn Belt has increased substantially in the past several years. Recently, however, potassium (K) deficiency symptoms have been reported in many fields. These observations have occurred even though soil test values for K have been in the high range. As the number of reports of K deficiencies increased, it was... |
7. Corn Yield Response to the Urease Inhibitor N-n-Butyl Thiophosphoric Triamide (NBPT) When Applied with UreaUrease inhibitors are applied to reduce ammonia volatilization and immobilization losses from surface-applied urea or urea-ammonium nitrate solutions (UAN). The urease inhibitor N-(n-buty1)thiophosphoric triamide (NBPT) was evaluated at rates of 0.25 to 1.0 % (w/w) in 78 U.S. trials conducted with corn (Zea mavs L.) during the period 1984 to 1989. When averaged over N rates for all locations and years, NBPT increased grain yields by 4.3 bu/acre when compared to similar rates of unamended urea. A... |
8. Dietary P Management to Reduce Soil P Loading from Pig ManureThe potential use of phosphorus (P) based land application limits for animal manure has increased the importance of optimizing animal feed P management. The specific objectives of this study were to determine the impacts of using high available P (HAP) corn and phytase on 1) P uptake and excretion by young pigs, and 2) total P, PA-P, and water-soluble P (WSP) levels in fiesh manure generated by these pigs during a seven day digestibility trial. Our results show that, compared to the control diet... |
9. Effect of Alfalfa Stand Density or Cutting Management on Nitrogen Supplying CapacityEconomic, energy and environmental considerations are making the efficient use of nitrogen fertilizers increasingly important for Wisconsin crop producers. Excessive nitrogen applications cannot be tolerated environmentally due to the potential for N leaching to groundwater, or economically due to the relatively high cost of N fertilizers. The potential exists for many producers, farming in legume rotation, to unknowingly over-apply N by not fully applying credits for previously grown alfalfa. A... |
10. Effect of Irrigation and Nitrogen on Corn Yield and ProfitAn understanding of the interaction of various inputs on corn yield and profit is important in decision making for corn production. This study was conducted to evaluate 1) the effect of irrigation, hybrid, seeding rate and nitrogen rate on yield of corn and 2) the effect of these inputs on marginal return and cost per bushel for corn production. This study was conducted for three years at two 1 ocations on a Conover 1 oam and a Zi lwaukee clay soi 1 . The three years represented a normal rainfal... |
11. Effect of Potassium Rates and Placement on Soil Test Variability Across Tillage SystemsExperiments were conducted from 1994 through 1996 at the Dixon Springs Agricultural Center and the Belleville Research Center to evaluate K rates (60, 120, and 180 Ib KzO per acre) and placement methods in a corn and soybean rotation using chisel tillage (CT) and no-till (NT) practices. Four placement methods were used: surface broadcast, dribble, 10-inch wide surface band over each row, and banding 30 Ibs K20 per acre 2 inches to the side and 2 inches below the planted seed (remainder of the K ... |
12. Effect of Tillage, Rotation, and Nitrogen Rate on Rainfed Corn Yield and Nitrogen UptakeDetermining the long term effect of tillage, rotation and nitrogen rate in typical cropping sequences is important in making sound agronomic decisions. In northeast Nebraska rainfall is the major deternlinant of yield. In 1956 a tillage study was initiated to determine the effect of tillage. rotation and nitrogen rate on corn and soybean yields. Spring plow. disk and no-till treatments were applied to continuous corn and co1-n follo\ving soybeans on a Kennebec silt loam. Five nitrogen rates (0. ... |
13. Effect of Time and Rate of N Application on N use Efficiency and Surface Water Contamination with NitratesNitrate levels in excess of the public health standard of 10 mg N/1 in public water supplies along - with concern about hypoxia in the Gulf of Mexico have drawn renewed interest to improving fertilizer N use efficiency. Prior research has indicated that some farmers may be unkaowingly contributing to these problems. The objectives of this research were to: determine the effect of rate and time of N application on nitrate-N concentrations in water from tile lines and to evaluate the effect of pre... |
14. Establishing (and Differentiating) On-farm Research and Demonstration TrialsAs the 1990s begin, funding agencies are looking beyond the traditional definition of who does "research." While university, USDA and private industry have traditionally conducted research in the past, grassroot organizations, local agency personnel and individual farmers are now proposing and implementing research of various types. An overall trend seems to be for research experiments to be evaluated on farmersf fields. Some of this movement may be a political statement against traditional meth... |
15. Fertilizer Recommendations in the Eastern Corn BeltThe purpose of this paper is to discuss fertilizer recommendations for corn and soybeans made by three universities and by three private institutions in the Eastern Corn Belt. For lack of a better term, the six sources of recommendations will be referred as "labs", a commonly-used abbreviation for soil testing laboratories. This term does not accurately describe Countrymark which uses the results from other labs on which to base its recommendations. ABSTRACT Nitrogen (N), phosphorus (P) and pota... |
16. Foliar Fertilization of SoybeansExtensive research addressed foliar fertilization of soybeans at reproductive stages during the 70s and 80s. The soybean plant has been characterized by markedly reduced root activity during late seed development and increased translocation of nutrients and metabolites fiom other tissue into the seed. This depletion of numents from leaves could result in decreased photosynthesis. leaf senescence. and lower grain yields. Researchers theorized that if nutrients were applied directly to the foliage... |
17. Identifying Critical Sources of Phosphorus Export from Agricultural WatershedsPhosphorus (P) is an essential element for plant and animal growth, and its input to agriculture is necessary to maintain profitable crop and animal production. Eutrophication, the natural aging of lakes or streams brought on by nutrient enrichment, can be accelerated by P inputs to fresh waters from human activities (Carpenter et al., 1998; Schindler. 1977). Eutrophication has been identified as the main problem in surface waters withimpaired water quality (USEPA. 1996). It restricts water use ... |
18. Improving Nitrogen Recommendations in NebraskaSoil nitrate tests offer a unique opportunity to fine tune our nitrogen management into the 90's. Nebraska has had a long history of research and extension programs using soil nitrate levels to modify fertilizer nitrogen recommendations. Because of our climatic regime nitrate tests work well across the whole state. We have a large data base on research plots that shows the tests are very effective. A large number of farmer demonstrations conducted over the last 10 years also show that the techno... |
19. Influence of Sulfur Source on CornSulfur is an essential plant nutrient. Medium and fine texture high organic matter soils in South Dakota usually supply adequate levels of sulfur to plants. Very sandy soils are less capable of supplying sulfur to plants but even these soils usually provide adequate sulfur for plant needs. However, in recent years above average precipitation may have caused leaching of sulfur, possibly resulting in sulfur deficiencies. In addition, spring soil temperatures have stayed cool, likely slowing decay ... |
20. Interpretation and Presentation of Research InformationCrop yields have increased over time as the knowledge base supporting crop production practices has increased. The educational process of transfer of information based on research bears a deep sense of responsibility. Selection of research results on which to base recommendations is a matter of judgement that can be enhanced by proper statistical analysis. Experimental objectives, experimental design, treatment selection, number and years of experiments, environments in which the experimentatio... |
21. Long Term Tillage and Fertility Effects in CornA long term study to evaluate tillage methods and fertilization practices on corn under monoculture was initiated in 1970. Effects on grain yields and soil property changes were evaluated over 20 growing seasons. Four tillages evaluated were continuous conventional, alter- nate till (2 years no-till: 1 year conventional till), continuous chisel till, and continuous no-till. The five fertilizer treatments evaluated were: control, 0-0-0; 175-0-0; 160-0-0 broadcast plus 15-80-120 row banded at plan... |
22. Low-Phytate Corn- A Genetic Approach to Manure-P ManagementManaging nitrogen (N) and phosphorus (P) contained in manure produced by monogastric animals (primarily poultry and swine) is complicated because the N:P in corn grain is 6: 1 but only 3: 1 or less, in the manure. The P content in manure fiom monogastric animals becomes elevated because corn grain and many other feed sources contain most of their P as phytic acid (phytate) which is unavailable to these species because they lack the intestinal enzyme, phytase, needed to metabolize phytic acid-P. ... |
23. Manure ManagementNutrient management should be looked at as an integrated, continuous process. It starts with an assessment of the overall nutrient balance on the farm If this simple assessment indicates a nutrient imbalance, a more detailed assessment will indicate specific field imbalances that need to be considered in the manure management process. Once an assessment has been accomplished, management options for dealing with the situation can be explored. If there is an overall nutrient imbalance on the farm,... |
24. Nitrate Test Clinics in MichiganNitrate contamination of groundwater in Michigan is becoming an increasing public concern. Fertilizer N, animal manures and rural septic systems have been implicated as possible nonpoint sources of contamination. A state wide program of monitoring nitrate N in soil and well water was initiated. In the spring of 1989 and 1990, 74 nitrate testing clinics were conducted. Over 3,600 soil samples and 1,900 water samples were analyzed for nitrate N using the nitrate ion-specific electrode. More soil n... |
25. Nitrification of Banded Liquid FertilizersField studies were conducted in 1990 at three sites to compare the relative effectiveness of ammonium thiosulfate (ATS, 12-0-0- 26s) , dicyandiamide (DCD) , and nitrapyrin (NP, ' N-Serve 24E' ) as nitrification inhibitors in combination with banded urea-ammonium nitrate (UAN). Applications were banded prior to planting spring wheat, and soil samples taken 2, 4, and 8 weeks after application. ATS, DCD, and NP inhibited nitrification at all three sites. ATS inhibited nitrification at the 4 week sa... |
26. Nitrogen Fertilization of SoybeanNitrogen (N) requirement of soybean is high because of the high protein seed produced. One bushel of soybean requires over 3.5 pounds of N in the grain alone. Symbiotic Nz fixation supplies N for soybean, but Harper (1 974) reported that only 25 to 60% of the N in a marure soybean piant comes from N fixation while the other 40 to 75% comes from the soil. However. application of N fertilizer to soybean remains a very controversial issue because of mixed results of previous research.... |
27. Nitrogen Management in Irrigated Corn Using Remotely-Sensed Imagery and Small-Plot ExperimentsNitrogen management for irrigated corn (Zea mays L.) grown along the Arkansas River Valley in Kansas is a concern due to the hig&ly leachable soils and high water tables (ranging fiom 10-50 A). Irrigated corn usually requires a high input of N fertilizer to achieve maximum yields, and most farmers in this area have been applying a uniform rate of nitrogen across their fields every growing season based on the following KSU N recommendation. N Rec = [YG * 1.35 lbs bu-'1 STA - PCA - PYM - PNST N Re... |
28. No-till Nitrogen Management Research in MissouriNo-till nitrogen management research on corn in Missouri has focused on the field response of N sources and placement. Results suggest consistent significant response to the use of a non-volatile N source when broadcast on the soil surface compared to N sources that contain urea and potentially can lose ammonia through volatilization. Knifed application of N in no-till has . consistently provided higher yields and N uptake compared to either surface band or broadcast application of potentially v... |
29. Optimizing Nitrogen Managament in Manure CornfieldsAnimal manure can provide N needed for production of corn. A major problem. however. is that manure is not perceived to be a reliable source of plant-available N. Much of the manure-N is known to be lost soon after application to soils, and much of the remaining N is known to persist as forms that are not readily available to the next crop. Recent studies involving 148 on- farm trials show that the late-spring test for soil nitrate has great potential for addressing this problem. The test involv... |
30. Remotely Sensed Crop Indices for Nitrogen StressCrop nitrogen (N) stress has a strong influence on plant vigor and growth. Under field conditions, crop N stress is frequently expressed through spatial variability in biomass production and grain yield. Remote sensing serves as a useful tool to monitor crop N status by characterizing canopy reflectance because certain wavebands (i-e., colors) are sensitive to chlorophyll and crop growth. Unfortunately, interpreting reflectance data in terms of crop stress is still an inexact science. Several in... |
31. Soybean Nitrogen Aquisition and UtilizationBecause of its high seed protein concentration soybean has a huge nitrogen demand, about 350 IbdA for a 65-bu/A crop. The nitrogen is supplied by two acquisition systems that operate in tandem. In early season the plant uses soil nitrate; later its nitrogen is acquired largely through Nz fixation. On highly fertile, Midwestern soils nitrate utilization peaks at about R3 and then declines sharply. With heavy nitrogen fertilization peak nitrate utilization can be extended through R5, but ordinaril... |
32. Soybean Nitrogen Contributions and Rotation EffectsCorn-soybean rotations are widely used in Midwestern grain production. These rotations usually produce higher corn yields and require less supplemental nitrogen (N) than corn grown following corn. The yield benefits are usually attributed to rotation effects, although the precise mechanisms responsible for the yield enhancement are often not well defined. Nitrogen contributions from soybean in rotations are also not well understood because nitrogen budgets for soybean show that soybean harvested... |
33. 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 sugges... |
34. Sulfur Fertilization of Smooth BromegrassStudies were initiated in 1987-88 on established smooth bromegrass at two sites in eastern Kansas to evaluate the effects of sulfur fertilization on bromegrass forage production and quality. Sulfur rates (0, 15, 30 lb S/ac) and sources (ammonium sulfate and ammonium thiosulfate) were evaluated. The addition of sulfur consistently and, in most cases, significantly increased bromegrass forage yields and forage S concentrations. Sulfur had little effect on forage protein levels. Ammonium thiosulfa... |
35. The New Wisconsin Soil Test Recommendation ProgramThe modern Wisconsin soil testing program was originally developed in the early 1960's. It was revised rather thoroughly in 1970 and again in 1981. New research advances, additional correla- tion and calibration data, changes in user needs, and shifts in philosophical viewpoint make it necessary to periodically review the soil testing program and the recommendations that emanate from that program. The current revision is an attempt to incorporate additional research, eliminate certain inconsiste... |
36. The Potential use of Polymer-Coated Urea as a Spring Nitrogen Source for WheatMost of the soils in Northwest Ohio are medium to fine texture with poor internal drainage. Tile drainage has improved these fields, but nitrogen loss still often occurs from denitrification, especially during cold and wet springs. Growers compensate for this potential loss by applying more N at green-up or split spring applications. both of which add costs. -4 slow release N fertilizer may reduce the need for more N or split applications. One of the new time release N products is polymer-coated... |
37. The Potential use of Polymer-coated Urea as an In-Furrow Fertilizer for CornMost of the soils in Northwest Ohio are medium to fine texture with poor internal drainage. Tile drainage has improved these fields, but nitrogen loss still often occurs from denitrification, especially during cold and wet springs. The use of no-till practices has accentuated the problem. Starter fertilizers at planting have often improved the early growth of corn under these cold and wet conditions. IIowever, weather conditions may prevent timely sidedressing after planting, and cause N deficie... |
38. Tillage and Potassium Effects on Potassium use Efficiency in a Corn-Soybean RotationA field study was conducted from 1994 through 1996 at the Dixon Springs Agricultural Center @SAC) on a Bonnie sil soil and at the SlU Belleville Research Center (BRC) on a Herrick sil soil. No-till (NT) and spring chisel tillage (CT) systems were compared in a corn-soybean rotation. Within each tillage system, potassium (K) rates of 60, 120 and 180 Ib K20 per acre were combined with four placement methods that included surface broadcast, 10-inch surface band over the intended row, surface dribbl... |
39. Trends in Soil Test P and K in IowaThe Iowa State University Soil Testing Laboratory has provided soil test information to Iowa farmers since 1931 when Professor Firkins began the service for no charge. The predecessor of today's lab was initiated in February, 1946 (~ik~) . The lab's records provide us with valuable information on the trends in the plant nutrient status of Iowa's soils (Figure 1). During the period from 1960 to 1981, the consumption of nitrogen (N), phosphate (P), and potash (K) fertilizer materials rose from 7.5... |
40. Variability of Soil Test Phophorus and Management of Phosphorus FertilizerSoil avdable phosphorus (P) can have appreciable spatial variation wluch could result in inefficient ferthzer use. The hlgh cost of mapping ttus variab&ty may make sit2 spedc management of P uneconomic. Seed-placing a small amount of P fertrli2er has been shown to increase gain yield of corn. Therefore. it may have potential for improving P use efficiency. Ah txperiment was conducted to evaluate the spatial pattern of soil test P and the spatial response of applied P fertilizer. The scale of P v... |