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1. Agricultural Impact on Groundwater QurlityThere has been an increasing awareness within Iowa of the impact of agriculture on groundwater quality. The data of Iowa Geologic Survey scientists from studies in northeast Iowa have focused attention on the Big Spring Basin area. A project to intensively study groundwater in the Big Spring Basin is underway. The project includes the active cooperation and participation of the following agencies: ISU Agricultural Experiment Station, Clayton County Soil Conservancy District ISU Cooperative Extension... |
2. High Yield Corn ResearchThe objective of this study was to evaluate four corn hybrids at 15 and 30 inch row spacing and at plant densities of 28,000 and 34,000 plants per acre. The irrigated study was conducted at East Lansing on a Metea loamy sand soil. The 15 inch row spacing was obtained by back-planting in between 30 inch rows. Other cultural and management inputs are described at the bottom of Table 1. The first obviously noticeable difference in 1984 was the uneven stand in the 15 inch row spacing particularly for... |
3. Corn Stem Nitrate N Content-Grain Yield Relationships and Their use as a Basis for Sidedress N Rate RecommendationsThe objectives of this study were to confirm the relationship between nitrate nitrogen (NO3-N) content of basal corn steras and grain yield in Iowa, to establish crltical levels of stem NO3-N content for dtaining various levels of mximum yield, and to perform preliminary calibration of yield responses to sidedressed nitrogen (N) at various levels of st-Rm NO3-N content. Six sites across Iowa with a wide range of physical and environmental conditions were selected. N fertilizer was applied preplant,... |
4. Effect of Time of N fertilizer Application on Corn Grain Yield in IowaThe current concern about the impact of nitrogen (N) fertilizer use on the environment has caused a shift in the thinking about N management. Crop producers are interested in techniques (application methods) that will maximize the amount of N fertilizer harvested in the crop, and conversely minimize the amount remaining in the soil after harvest. Split applications or sidedress applications are common approaches currently being studied as a way to increase the efficiency of N fertilizer management.... |
5. Nitrogen Fertilizer Requirements for No-till cornConservation tillage is associated with higher surface crop residue levels, larger more stable soil aggregates, and generally higher surface soil water contents compared to conventional tillage. The changes in residue management and overall soil water regime under conservation tillage may result in different spatial distributions (laterally and with depth) of nutrients. In general, nitrogen fertilizer applied as broadcast urea is not recommended for no-till systems because of the possibility of ammonia... |
6. Nitrate Soil Testing Correlation and Calibration Eastern Corn BeltCurrent economic and environmental concerns have increased the interest in developing methods to help manage nitrogen (N) fertilizers as efficiently as possible. There is a concern that fertilizer N that remains in the soil following harvest may be leaching below the root zone of crops and eventually ending up in groundwater. Agronomists throughout the corn belt are actively evaluating methods to manage N fertilizer as efficiently as possible.... |
7. 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... |
8. Flooded Soil Syndrom and P Deficiencies on Four Iowa SoilsSeveral million acres of Midwest cropland were inundated during the floods of 1993. The length of inundation was from a few days to several months. In some areas growing crops were drowned out and other fields could never be planted. As the water receded and acres of barren ground were exposed, the reality of the disaster gave way to concerns for the 1994 crop and the development of Flooded Soil Syndrome. Flooded Soil Syndrome produces' symptoms similar to Fallow Syndrome which was originally identified... |
9. 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... |
10. Nitrogen Loss from Sprinkler Applied Beef Feedlot EffluentLoss of nitrogen from sprinkler applied beef feedlot effluent can be costly for both the producer and the environment. Sprinkler application of effluent is common throughout the Great Plains, though little work has focused specifically on N losses from beef feedlot effluent. We quantified ammonia (NH 3) and nitrous oxide (N2O) losses from beef feedlot effluent applications under field conditions including variations in soil pH, soil water content, ammonium (NH 4+) concentration of the effluent, and... |
11. Optimizing P Based In-Furrow Starter Fertilizer in Fields with Variable Soil Test P LevelsSoils in Minnesota are highly variable in chemical properties, particularly pH which can range from acidic to basic within a single field. In-furrow starter fertilizer is popular if fields with variable- and high (>7.5) pH fields to enhance early plant growth. The purpose of this study was to determine if in-furrow starter fertilizer rate should be varied in fields with varying pH and if starter fertilizer can increase yield in the presence of broadcast P applied at a non- limiting rate. Eight field... |
12. Do Soil Nitrogen Tests Relate to Nitrogen Mineralization in First-year Corn Following Alfalfa?Corn (Zea mays L.) is the most frequent first-year crop grown following alfalfa (Medicago sativa L.) in the Upper Midwest. In the majority of cases, first-year corn does not respond to fertilizer N, but sometimes large amounts are needed to optimize yield. The pre-sidedress and Illinois soil N tests (PSNT and ISNT, respectively) are early-season tests used to predict corn yield response to fertilizer N. These tests measure specific fractions of soil N and define a critical concentration to separate... |
13. Comparison of Soil Properties under Long-Term Crop Rotation and TillageShifts in cropping systems from long-term rotations including forages to mostly annual crops has intensified tillage, but has also led to the development of conservation tillage practices such as no-till. There is a shortage of information about the interactive, long-term effects of rotation and tillage on soil quality. The objective of this study was to assess soil chemical and physical properties after 15 years of crop rotation and tillage treatments. Continuous corn (Zea mays L.) (CCC), corn-soybean... |
14. Managing Riparian Buffers to Improve Soil Structural PropertiesFifty-five percent of Kentucky's stream impairments have been attributed to agriculture. Riparian buffer management may improve buffer effectiveness and reduce agricultural contaminants impairing water quality. Three mowing regimes and one native grass establishment regime were imposed in the riparian buffer zone surrounding a tributary of Cane Run Creek in Fayette County KY. Treatment plots measured 10m x 15m, with 10 replications of each treatment. One year after treatment, root biomass, soil aggregate... |
15. Variable Fertilizer Nitrogen Application Based on the Delta Yield Index- A Field StudyA quick review of the both the scientific and popular literature indicates that many different approaches have been suggested for the prediction of variable fertilizer N applications in the field. In previous meetings of this conference we have presented the general outline and approach taken for our site-specific crop management project in Ontario. Briefly, historical data sets of grain corn response trials to fertilizer N (encompassing some 300 site-years worth of data) indicated that most yield... |
16. Re-Evaluating Rate, Time, and Placement of Urea and Other Nitrogen Sources in MinnesotaUrea is increasingly an important nitrogen (N) source in Minnesota. Approximately 43% of our farmers use urea as their major N source. In the southwestern, south-central and west-central areas approximately 45% of the N is applied in the fall, 50% is applied in the spring, and 5% is applied at sidedress. While most of those that use urea as the major N source apply it in the spring, approximately 4% do the major application with urea in the fall and there are others that apply some of their N... F. Fernandez, K. Fabrizzi, J. Vetsch, D. Kaiser |
17. Soil N2O emissions in continuous corn as affected by 4R and cover cropsCover crops and 4R nitrogen (N) management are promoted as key practices for reducing nitrate leaching losses, but their impacts on nitrous oxide (N2O) emissions remain less certain. This study evaluated soil N2O emissions and grain yield under different timing of N application and cover crops for two years in a tile-drained continuous corn system. Treatments were 224 kg N ha-1 split-applied in fall + pre-plant (Conventional), pre-plant + side-dress (4R), 4R +... G. Preza fontes, L.E. Christianson, C.M. Pittelkow |
18. Evaluation of Potassium Fertilization Strategies for Corn and Soybean: the Buildup PhasePotassium is a crop nutrient which can severely limit yield potential when deficient. Potassium fertilizer historically was low cost. Price increases have resulted in more questions as to the benefit from potassium applied for corn and soybean. The objective of this study was establish a set of trials which vary in soil test K level to be used to determine corn and soybean grain yield response to K based on initial soil test and to compare soil K analysis on moist versus air dried soil samples... J. Vetsch, D. Kaiser |
19. Prediction of Corn and Soybean Grain Yield Response to P in Minnesota Using the Haney H3A and Mehlich-III TestsMinnesota soils are highly variable in P availability due to the wide range of chemical properties. Currently, two soil tests are used to measure soil P in Minnesota, the Bray-P1 for pH<7.4 and the Olsen P for pH>7.4. The purpose of this study was to correlate crop response in corn and soybean rotations to the Bray-P1, Olsen, Mehlich-III, and Haney H3A extractions and to determine critical concentrations for each extraction method. Soil P tests were also correlated with one another to determine... D. Kaiser, L. Leverich, J. Vetsch, J. Strock |
20. Can ProveN Reduce Corn Nitrogen Requirement in Minnesota?ProveN is a microbial product applied in-furrow with the goal of reducing the total amount of nitrogen fertilizer needed for corn (Zea mays L.). Six field trials were established over three growing seasons in Minnesota to evaluate corn response to nitrogen with and without ProveN applied at planting on the seed. Nitrogen was applied as urea prior to planting at five locations and split applied with 1/3 of the total rates of nitrogen applied at -planting, at V4, and V8 growth stages. ProveN... D. Kaiser, J. Vetsch, M. Currie |
21. Influence of Biological Seed Treatment on Soybean Grain Yield in the U.S.Biological seed treatment in soybean (Glycine max (L.) Merr.) is a growing market in the U.S., with multiple microbially active ingredients and several proposed benefits. Some of the claimed benefits include improving nitrogen fixation, stimulation of root growth, increasing phosphorus, sulfur, and other nutrient absorption, and control of diseases, with the aim to increase soybean grain yield. Farmers are often bombarded with marketing claims about biological seed treatments. In many... F. Colet, R.A. Vann, S.P. Conley, S.L. Naeve, E.G. Matcham, S. Mourtzinis, L.E. Lindsey |