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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. 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... |
10. 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 |