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1. Adjusting N Recommendations Based on a Previously Grown CropNitrogen recommendations in North Dakota are based on a yield goal multiplied from some empirically derived factor in a linear formula. There are a three adjustments to the N recommendations that result form these formulas (Franzen and Cihacek, 1996). They are the soil test nitrate-N to some depth, a sampling date adjustment ifthe sampling was conducted in the fall prior to September 15, and a previous crop credit. Two of these three adjustments are based on some knowledge regarding mineralization... |
2. Use Of Corn Height To Improve The Relationship Between Active Optical Sensor Readings And Yield EstimatesPre-season and early in-season loss of N continues to be a problem in corn (Zea mays, L.). One method to improve nitrogen use efficiency is to fertilize based on in-season crop foliage sensors. The objective of this study was to evaluate two different ground-based, active-optical sensors and explore the use of corn height with sensor readings for improved relationship with corn yield. Two different ground-based active-optical sensors (Greenseeker�, Trimble, Sunnydale, CA; and Holland Crop Circle... |
3. Crop Yield Relationship to Remote Sensing Data Using Intensified Weighted Nonlinear Regression ModelsYield prediction is important for making in-season agronomic input decisions as well as for greater logistical decisions. In predicting the crop yield based on ground-based active optical sensing data, the ordinary statistical unweighted linear or nonlinear regression models are the most popular choices. However, these unweighted models may not be accurate enough for practical use because they are based on the assumption that each data point for regression is obtained with equal precision and that... |
4. Nitrogen Rate Revisions for Corn in North DakotaNitrogen rates in North Dakota have been based on a yield-goal or yield-potential formula for over forty years. The currently published formula (Franzen, 2010) is: Recommended N rate = (Yield Potential, bushels per acre) X 1.2 less N credits from previous crops and soil test nitrate to 2 feet in depth. A yield-based strategy was practical when N costs were relatively low and yields in North Dakota were at most 100 bushels per acre. However, due to improved germplasm developed at North Dakota State... |
5. Minimizing Nitrate Loss from Manure-amended Wisconsin Sandy SoilsThe impact of dairy manure application on nitrate leaching was evaluated at two sites with no manure history. Manure treatment (separated-solid manure, separated-liquid manure, separated- liquid manure plus a nitrification inhibitor, and two treatments with no manure) was the main plot. Each manured plot was split into six subplots with three receiving a single sidedress fertilizer application of 0, 56, or 112 kg N ha -1 while the others had two sidedress applications totaling 112 kg N ha-1 with... |
6. North Dakota Corn Recommendations for Preplant and Sensor Directed Sidedress NNitrogen rates for preplant N application in North Dakota have been drastically revised. The former yield-based strategy may have served when N costs were stable and relatively low and high yields in North Dakota were rarely higher than 100 bushels per acre. Due to improved germplasm developed at North Dakota State University and other northern Land-Grant Universities with favorable adaptation to North Dakota climate and soil conditions corn has become one of the most planted crops in the state.... |
7. Nitrous Oxide Emissions in Claypan Soils Due to Fertilizer Source and Tillage/Fertilizer PlacementNitrogen fertilization for agricu ltural production is a major contri butor to increased soil nitrous oxide emissions. These emissi ons may contribute to global warming and ozone depletion. Nitrogen fertilizer source and placeme nt can influence soil nitrous oxide (N 2O) emissions by affecting the concentration of ammonium and nitrat e available for nitrification and denitrification throughout the growing season. The objectives of this research were to quantify the effect of tillage / fertilizer... |
8. Grid Soil Sample Interpolation Using Geographicaly Weighted Regression and Random ForestSoil sampling is useful in agriculture for setting fertilizer application rates. High density soil samples can also be used for variable rate seeding and other precision agriculture applications. Half-acre grid soil samples were collected from 6 soybean fields, and phosphorous (P), potassium (K), and organic matter (OM) were measured. Each soil parameter was interpolated for each field, with terrain attributes as covariates, using two different methods: geographically weighted regression (GWR)... E. Matcham, S. Subburayalu, J. Fulton, E. Hawkins, P. Paul, L. Lindsey |