Proceedings
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1. Changes in Iowa's Soil Test P and K Interpretations and RecommendationsResearch results from long-term and short-term experimentation in Iowa have been consistent in the response or lack of response of Iowa field crops to applications of fertilizer phosphorus (P) and potassium (K) at various soil test levels for P and K. Analyses of the research data have established critical soil test values for P and K and the most economic soil test range for P and K to maintain (Mallarino, Webb, and Blackmer, 1991a and 1991 b; Mallarino and Blackmer, 1992 and 1994; Webb, Mallar... |
2. Corn Nitrogen Tests in MissouriExperiments were carried out in farmer fields starting in 1995 with the objective of evaluating or developing field-specific tests to optimize N fertilizer rates for corn. Because some of the soil nitrate tests seem to work differently when manure or alfalfa is in the cropping system, most farms had pairs of experiments, one with an organic N source and the other with none. Descriptions of the experimental locations are given below. Location 1 2 Year 1995 1995 1995 1995 1995 PROCEDURES Countv Ca... |
3. Correlation and Calibratin of the SMP Lime Requirement Test with Direct Titration of Soil AcidityThe SMP Buffer method (Shoemaker, et al, 1961) of routinely determining lime requirement on soil samples has been used at the University of Kentucky Soil Testing Laboratory (UKSTL) since the mid-1960's. Initial correlation and calibration for Kentucky soils was a result of incubating several soil samples over a period of time after mixing different rates of lime with them (D.E. Peaslee, 1975, personal communication). During the ensuing years, county agricultural extension agents have raised many... |
4. Effect of N Fertilization on Accumulation and Release of Readily-Mineralized Organic NIncreased nitrogen (N) fertilizer use has generated concern about groundwater contamination by nitrate (NO,?. The objective of this work was to determine how previous N management and cropping system affect fertilizer N use efficiency. Research plots from a long-term N rate study on a silt loam soil were used to evaluate the impact of long term N rates on immobilization and mineralization of fertilizer N. Labeled '5~~,15~~, was applied at rates of 0, 60, 120, 180, and 240 lblacre to subplots of ... |
5. Effect of Rotation on Corn Yield and Economic Returns Under Composted Manure or Fertilizer ManagementThe benefits of growing corn in rotation with other crops as opposed to continuous corn have been mentioned in numerous research and technical publications. The benefits of adding to the crop mix include improved soil structure (Raimbault and Vyn, 1991) and soil nutrient availability (Copeland and Crookston, 1992). especially from rotations that include legumes such as soybeans or legume cover crops. Other benefits include better weed (Bhowmik and Dow, 1982). insect (Benson, 1985) and disease co... |
6. Effect of Subsoil Tillage on Crops Grown in No-Till and Reduced Till ManagementsThree different subsoil tillage experiments were conducted in southern Illinois on soils with root-limiting claypans that restrict crop growth. In the first experiment conducted at the SIU Belleville Research Center, subsoiling to 16 inches depth was compared to no subsoiling in a field that had been in long term, continuous no-till corn production. After 4 years of study, only small corn and soybean yield increases have observed with the tillage (2.0 bu/ac for corn and 1.0 bu/ac for soybeans) .... |
7. 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, Ill... |
8. Influence of Elemental Sulfur on Soil pH and Soil Test LevelsSoil test summaries from South Dakota State University Soil Testing Lab show that 16 percent of South Dakota soils have a pH of 7.6 or higher. These high pH soils can reduce nutrient availability to plants. A major concern is for reduced phosphorus availability and fertilizer use efficiency. High pH soils also reduce the availability of micronutrients such as iron and zinc. Due to these issues, questions are often asked on how to reduce soil pH. A number of materials such as sulfuric acid, alumi... |
9. Manure Management Policy IssuesTraditionally nutrient management has been concerned with optimizing the economic return from nutrients used to produce a crop. The main emphasis was on the expected crop response from adding nutrients. In practice however, manure is not always applied to optimize plant nutrient use. Historically, a common practice has been to apply commercial fertilizer without giving credit for nutrients already applied in manure. Applying manure in excess of plant needs, or at the wrong time, or handling it i... |
10. N x K Interactions- CornA study was conducted at OARDC-Western Branch near Springfield, OH for 4 years starting in 1992 to investigate the effects of N and K on corn production N uptake. The soil series was a Crosby Silt Loam with approximately 2.5% organic matter. All nutrients were in the above average levels on the soil test except for exchangeable K levels. See table 2 for soil test K levels. The corn hybrid Countryrnark 735 was seeded approximately the last week of April at 35,000 seeddacre. A split plot design w... |