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1. North Central Regional Nitrate Soil Testing ProjectAlthough preplant soil nitrate (NO -N) tests have a long history of 3 successful use in semi-arid regions of the Western and Great Plains region of the United States (Hergert, 1987), soil NO -N testing in humid 3 regions is currently receiving substantial research attention. One of the most promising approaches to KO testing in the higher rainfall areas 3 of the Midwest and Eastern states is use of the pre-sidedress soil NO test (PSNT) (Magdoff et al., 1984). Research conducted in the humid 3 regions... |
2. Predicting Subsoil Nitrate Content from Surface MeasurementsPreplant soil profile nitrate (NO,-N) tests are effective for I predicting corn (Zea mays L.) responsk to applied N. The difficulty of obtaining profile soil samples is one of the main obstacles to more extensive use of preplant tests. One approach to overcoming this barrier is to develop and use models to predict subsoil NO -N contents 3 from surface soil NO -N measurements. Data from 2295 routlne field 3 samples submitted to the University of Wisconsin Soil and Plant Analysis Laboratory from 1989... |
3. Assessing the Source of Groundwater Nitrates- And You Thought Good Wine Took TimeControversy continues with elevated groundwater nitrate concentrations being attributed to N fertilizer use. Current research defining best management practices in farming system K management seldom addresses the influence these practices have on groundwater. Why? The results of this Missouri research show that the influence of management on groundwater nitrates may last for decades. The study provides support for time requirements when assessing farming system impact on groundwater quality. ... |
4. 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... |
5. Nitrogen Recommendations and Optimum Nitrogen Rates- How Do They CompareThe goals of University N recommendations for corn are to suggest adequate amounts of N to maximize economic return to the grower and simultaneously avoid excess N additions that can contribute to water quality problems. With increasing concerns about the contributions of aoricultural N to groundwater nitrate and to hypoxia in the Gulf of 3 Mexico. the appropnateness of N recomn~endations and their research basis are increasingly questioned. In addition, University N recommendations are often being... |
6. Long-Term Nitrogen Fertilization Effects on Corn Yields and Soil PropertiesA long-term experiment (1 958-2002) provides information about the sustainability of long-term nitrogen (N) fertilizer use and continuous corn production in the northern Corn Belt. The experiment includes three N rates (none, medium, and high) applied annually in a randomized complete block design with four replications. Nitrogen rates in the medium and high categories increased over time and are currently 125 and 250 lb Nlacre. Lime treatments were imposed on the long-term N rates in 1985 using... |
7. Measuring Water-Extractable Phosphorus in Manures to Predict Phosphorus Concentrations in RunoffWater-extractable phosphorus (WEP) in manures can influence the risk of P losses in runoff when manures are land applied. There is some uncertainty about how WEP in manures should be determined. Specifically, are WEP measurements affected by manure sample handling before analysis, and what manure extraction procedures are most appropriate for predicting potential P runoff losses after manure application? We evaluated several manure handling and extraction variables in determinations of WEP in manures... |
8. Determining Economic Optimum Nitrogen Rates with the Illinois Soil Nitrogen Test and Soil Organic Nitrogen FractionsDevelopment of a diagnostic test to estimate soil N supplying capability is a continuing research need. The Illinois soil nitrogen test (ISNT) has been proposed as a method for adjusting corn (Zea Mays L.) N recommendations for to account for soil organic N contributions. We evaluated the ISNT as a tool for predicting corn N response in Wisconsin by comparing ISNT values and corn N response data from-81 experiments conducted between 1984 and 2004 with a range of crop rotations, management histories,... |
9. Validating the Wisconsin P Index with Measured Runoff P Losses From Agricultural FieldsPhosphorus (P) indices have been developed by most states in the USA for use as planning tools to assess the risk of P loss and identify appropriate management alternatives to control these losses where needed. Little information is available on the relationshp between P index values and actual P runoff losses in the field. We compared annual P losses in runoff measured at 2 1 field or sub-watershed locations with Wisconsin P index values calculated for the same areas. The research sites included... |
10. Nitrogen Mineralization Estimates for N Rate SuggestionsTo improve the accuracy of N rate recommendations for corn, reliable estimates of soil N supplying capability are needed. The important influence of soil N supplying capability on estimating corn N needs is illustrated by a recent compilation of data on corn yield response to N fertilization fiom over 300 experiments in Illinois, Iowa, Minnesota, and Wisconsin showing that 50 to 70% of the observed corn yield was produced with N supplied by the soil alone (Sawyer et al., 2006). The soil available... |
11. Accuracy of Credits and Soil Indicies for Predicting Nitrogen Response in Corn Following AlfalfaCorn is the most frequent first- and second-year crop following alfalfa in the upper midwestern United States. In the majority of reported cases, there is little need for additional fertilizer N to optimize yield of first-year corn following alfalfa. For second-year corn following alfalfa, fertilizer N is needed in about one-half of cases and the economically optimum N rate (EONR) has varied greatly in responsive fields. The objective of this research was to use literature data to evaluate the accuracy... |
12. Stand Age Affects Fertilizer Nitrogen Response in First-Year Corn Following AlfalfaThrough a symbiotic relationship with soil bacteria, alfalfa can acquire nitrogen (N) from the atmosphere, use the N for its own growth, and contribute large amounts of N to subsequent crops. To estimate this N contribution, most land-grant universities use book-value N credits based on alfalfa stand density at termination. However, a recent literature analysis indicated that alfalfa stand density is not a reliable predictor of grain yield response to fertilizer N in first-year corn. That analysis... |
13. Cover Crops Influence Soil Health and Nutrient Cycling in a Multi-Location Study in South DakotaSoil without living roots potentially loses mobile nutrients and retains excess water. Unprotected soil degradation and erosion enable the loss of carbon and nutrient rich top soil. Cover crops provide armor for the soil protecting from carbon and nutrient loss. Cover crop blends may influence soil health parameters and nutrient cycling. This multi-locational study depicts the influence of cover crop species blends with varying grass and broadleaf concentrations on established soil-health indicators... D. Sanyal, J. Wolthuizen, D. Karki, J. Clark, A. Bly |
14. Does cover crop composition improve soil health and enhance nutrient availability to cash crops?Crop and livestock producers in South Dakota are showing greater interest in cover crops for the multidimensional benefits it can provide towards enhanced nutrient availability to the cash crops and livestock nutrition. Growers use different blends of grasses and broad leaves, mostly legumes and brassicas, as cover crops. We hypothesized that carbon and nitrogen ratio and fiber composition in those cover crop residues regulate the nutrient release, thus influence the processes regarding nutrient... D. Sanyal, A. Rahhal, H. Bielenberg, J. Clark, J. Wolthuizen, A. Bly |
15. Do cover crops improve soil health and enhance nutrient availability to cash crops?Bare soils are prone to erosion and lose soluble nutrients. Cover crops provide protection to the soil against erosion and nutrient loss. We hypothesized that the cover crops should uptake available nutrients from the soils in the fall when there is no cash crop, assimilate the nutrients in their tissues, and in the following spring, should release the nutrients back to the soil during the next cash crop growing season. In our study, we are quantifying the nutrients taken up by the cover crops... D. Sanyal, A. Rahhal, H. Bielenberg, J. Wolthuizen, J. Clark, A. Bly |
16. No-till and Cover Crops Influence Soil Health and Nitrogen Rate and Timing Recommendations: Early ResultsThe idea of improving soil health has become increasingly more talked about by researchers, agronomists, and farmers in the past five years. Management practices such as no- or reduced-tillage and planting cover crops are recommended to improve soil health because of their potential to improve organic matter and soil structure leading to a greater capacity to hold water and nutrients needed for plant growth. Research in South Dakota has been occurring these past two years to determine the influence... J.D. Clark, A. Bly, D. Karki, D. Sanyal, J. Wolthuizen, P. Kovacs |
17. Cover crops nutrients uptake did not cause yield loss in cornBare soils are susceptible to erosion and nutrient loss. Cover crops and residues provide physical protection against erosion and nutrient loss, and improve nutrient cycling as well as biodiversity. We hypothesized that cover crops store available nutrients from the soil in the fall and release them the next spring for the next cash crop, minimizing potential nutrients loss with no adverse effect on cash crop yield. A four site-year study throughout South Dakota was conducted to compare... |
18. Can Cover Crops Help to Improve Soil Health While Having a Positive Effect on Corn Grain Yield?Cover crops have recently gained attention in the U.S. Mid-west because of their potential to increase soil organic matter and improve overall soil health. There is some concern however, that cover crops may negatively impact corn grain yield. This study was conducted to determine the effects that different cover crop mixtures have on soil health measurements and corn grain yield at increasing nitrogen rates. Cover crops were planted in the fall as a dominantly grass mixture, dominantly... |