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| Filter results8 paper(s) found. |
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1. Spatial Analysis of Yield-Limiting FactorsThe spatial relationship between crop yields and soil and site parameters was modeled using several methods. Yield maps estimated by projection pursuit regression and neural network analysis agreed well with measured yields. These methods also allowed generation of response curves for estimated yield as a function of each of the input parameters. These response curves were useful for investigating the relationship between yields and individual soil and site parameters. ... |
2. Spatial Prediction of Crop Productivity Using Electromagnetic InductionAn inexpensive and accurate method for measuring water-related, within-field soil productivity variation would greatly enhance site-specific crop management strategies. This paper reports on investigations to use an electromagnetic induction (EM) sensor to map claypan (Udollic Ochraqualfs) and alluvial (Typic and Aquic Udipsarnnlents, and Aeric Fluvaquents) soil conductivity variations and to evaluate the relationship of EM measurements to grain crop production. Grain yield measurement was obtained... |
3. An Evaluation of Methods for Determining Site-Specific Management ZonesNumerous procedures have been examined for identifymg management areas within fields. Traditional soil surveys give a general understanding of the effects soil mapping units have on crop productivity. In the USA. county soil surveys report the average grain yield of major crops by soil series. Slope position and landform are topographic features thal also have been used to explain water and crop productivity relationships (Mulla et al., 1992; Sudduth et al., 1997). Generally, footslope positions... |
4. Assessing Spatial and Temporal Nutrient Dynamics with a Proposed Nutrient Buffering IndexContinued adoption of precision agriculture will lead to the accumulation of spatially and temporally dense soil fertility and yield data. Current soil fertility recommendation strategies use regional estimates of soil buffering properties to adjust application rates. A site specific nutrient buffering index (BI) is presented that uses accumulated yield maps and soil test data to locally estimate soil buffering properties relative to fertilizer additions and crop removal. BI is a quantity-intensity... |
5. An Environmental Assessment of Sensor-Based Variable-Rate Nitrogen Management in CornIn order to address the problem of nitrate contamination of surface and ground waters, various methods have been used to try to account for spatial variability of N within agricultural fields. One approach to account for this variability and thereby reduce nitrate pollution is in-season site- specific N application according to economic optimal N rate (EONR). Recently, active crop canopy sensors have been tested for mid-season, on-the-go N fertilizer application in corn. This 2004 and 2005 study... |
6. Response Surface Models Of Subsoil K Concentration For Loess Over Till Soils In MissouriCrop uptake of potassium (K) has demonstrated sensitivity to subsoil variation in K content. This fact has not been sufficiently considered in K management strategies in part due to logistical difficulties in sampling spatially variable subsoil K. We propose a simplified soil factorial model, a response surface, to enable site-specific accounting of whole root zone K supply for loess over till soils. We compared the performance of two peak functions and a non-parametric local regression procedure... |
7. What Do You Do When Your N-Rich Reference Fails?In recent years, canopy reflectance sensing has b een investigated for in-season assessment of crop N health and fertilization. Typically, the procedure followed co mpares the crop in an area known to be non-limiting in N (the N-rich area) to the crop in a target area, which may be inadequately fertilized. Measurements from the two areas are used to calculate a relative reflectance to represent the potential need for add itional N fertilizer. Establishing N rich areas or strips is often inconvenient... |
8. What are the Benefits of Canopy Sensing for Variable-Rate Nitrogen Corn Fertilization?Canopy reflectance sensing for assessing crop N health has been proposed as a technology on which to base top-dress variable-rate N applicat ion. The objective of this research in Missouri was to evaluate the economic a nd environmental benefit of activ e-light crop-canopy reflectance sensors for corn N rate decisions. A total of 16 field-scale experiments were conducted over four seasons (2004-2007) in three major soil areas. Mu ltiple blocks of randomized N rate response plots traversed the length... |