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1. Chemical and Biological Changes Resulting from Soil SubmergenceFlooding of a soil for rice production results in significant short and long term physical, chemical and biological changes in soil properties. These changes may have significant impact of the availability of nutrients for plant growth both for aquatic plants growing in the flooded soil and upland plants on the soil when not under flooded conditions. Chief among these nutritional effects are accelerated nitrogen (N) losses, conversion of phosphorus (P) to more available forms during flooding then... |
2. Influence of Soil Test Phosphorus on Phosphorus Runoff Losses from South Dakota SoilsApplications of manure and fertilizer phosphorus (P) to soil in excess of optimal crop requirements leads to a buildup of soil test phosphorus (STP) and increases the risk of offsite transfer of P during heavy precipitation events. The first step to developing effective manure and fertilizer P application strategies for South Dakota is to evaluate the relationship that exists between soil and runoff P. The objectives of this study were to: 1) determine the relationship between STP and runoff P concentrations... |
3. Nitrogen Non-Cycling from Cover Crops Grown Before Corn and Spring Wheat-Unexpected Early Project ResultsNitrogen credits in North Dakota State University fertilization recommendations include those anticipated from the previous year annual legume crops (field pea, lentil, soybean, chickpea) and from terminated alfalfa. In addition, it was established in the region that sugarbeet tops returned to the soil may have an N credit potential of up to 80 pounds of N per acre (Crohain and Rixhon, 1967; Moraghan and Smith, 1994a; Moraghan and Smith, 1995a; Moraghan and Smith, 1995b; Franzen et al.,... D. Franzen, A. Wick, H. Bu, L. Ressler, J. Bell, M. Berti, C. Gasch |
4. Recalibration of Potassium Requirements for Corn in North DakotaThe previous North Dakota potassium recommendations for corn were borrowed from central Corn Belt states, where the dry soil-based 1 M ammonium acetate extraction for soil test K was utilized with a critical K value of 150 ppm. This value was adequate before 2000 because corn production was limited to only a few counties in southeastern North Dakota, and soil test K values were commonly above 300 ppm. However, the intensification of corn production in these counties and an increasing acreage around... D. Franzen, J. Breker, M. Rakkar, A. Chatterjee |
5. Post-Harvest Soil Nitrate Following Corn Production in Eight Midwestern StatesApplying nitrogen (N) at economically optimal rates (EONR) and at times of rapid crop uptake are practices that are thought to minimize the amount of residual soil nitrate (RSN) in the profile that may be susceptible to loss. The objective of this study was to evaluate the effects of rate (0 to 280 lb N/a in 40 lb increments) and timing (pre-plant (PP) or PP plus V9 sidedress (PP+SD)) of N application on corn grain yield and RSN in the top 3 feet of soil relative to the calculated EONR. Thirty-two... C. Bandura, C. Laboski, J. Camberato, P. Carter, R. Ferguson, F. Fernandez, D. Franzen, N. Kitchen, E. Nafziger, J. Sawyer, J. Shanahan |
6. Independence of Crop Yield and Nitrogen Rate Across SitesHistorically soil fertility specialists in the North Central States of the USA have constructed nitrogen (N) rate recommendations based on ‘yield goals’ or ‘expected yield’. Within the past ten years, there has been a general realization by soil fertility researchers that within a site or field there is a relationship between N rate and yield; however, because of soil and weather differences between sites there is no relationship in N rate studies with a large number of... D. Franzen, L. Sharma, H. Bu, E. Schultz, J. Breker, A. Denton |
7. Variation in Internal N Efficiency of Corn and Impact on Yield-Goal Based N RecommendationsInternal N efficiency (IE) is defined as bushels per acre (GY) produced per pound of N per acre (PMN) in the plant at physiological maturity (R6). Internal N efficiency defines the required amount of plant N content at R6 in a yield-goal based N rate recommendations (currently used in 30 U.S. states) and several commercial N recommendation models. Commonly IE is assumed to be constant at an approximate value of 0.8 bu lb-N-1 in yield-goal based recommendations. Our research objective was... M. Shafer, J. Camberato, P. Carter, R. Ferguson, F. Fernandez, D. Franzen, N. Kitchen, C. Laboski, E. Nafziger, R. Nielsen, J. Sawyer, J. Shanahan |