Proceedings
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| Filter results16 paper(s) found. |
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1. Assessing Crop Nitrogen Needs with Chlorophyll MetersTissue testing of corn leaves for nitrogen (N) concentration is not widely used because it is easier and perhaps more economical to apply sufficient fertilizer than to risk a yield reduction because of an N deficiency. Environmental concerns related to N fertilizer will require producers to improve N management practices to reduce the potential for nitrate leaching. Applying fertilizer N on an "As Needed" basis rather than using a "Lump Sum" approach has both environmental and economic implications.... |
2. Nitrogen and Water ManagementIt is difficult to separate N and water management when developing improved management systems for irrigated corn production. This is because adequate supplies of both N and water are critical for crop growth, but excesses of either or both can threaten ground water quality. Several N and water management systems were established at the Nebraska Management Systems Evaluation Area (MSEA) project to evaluate the impact of improved irrigation and N fertilizer management practices on production and/or... |
3. Remote Sensing Techniques to Identify N Deficiency in CornNitrogen management remains a primary concern for corn production. Environmental consciousness has increased the need for diagnostic techniques to identify N deficiencies to guide corrective measures or to provide feedback on management practices. This study was designed to evaluate several techniques that measure reflectance from corn plants to detect N stress. The experiment was located in Central Nebraska and involved four hybrids and five N rates. Leaf reflectance, canopy reflectance, and aerial... |
4. Remotely Sensed Crop Indices for Nitrogen StressCrop nitrogen (N) stress has a strong influence on plant vigor and growth. Under field conditions, crop N stress is frequently expressed through spatial variability in biomass production and grain yield. Remote sensing serves as a useful tool to monitor crop N status by characterizing canopy reflectance because certain wavebands (i-e., colors) are sensitive to chlorophyll and crop growth. Unfortunately, interpreting reflectance data in terms of crop stress is still an inexact science. Several indices... |
5. Early Season Stresses in CornSpatial variability in corn yield is frequently associated with lost yield potential caused by plant stresses. Early-season stresses are difficult to recognize because growing conditions (soil temperature and water status) are not ideal and seldom uniform throughout a field. The impact that climate has on plant growth is dificult to determine because it also affects nitrogen (N) availability. Nitrogen stress was imposed sequentially until the V8 growth stage and then all plots were sidedressed with... |
6. Vegetative Assessment of Phosphorus and Nitrogen Status in Maize Using Remote SensingAssess spatial variability of soil P and N is not only costly but also a time consuming processes. Remote sensing measurements of canopy spectral reflectance can provide a rapid and non- destructive method for assessing plant-canopy nutrient status. The main objective of this research was to detect P and N stress during the early corn growth by selecting specific wavelengths, or combinations of them, using narrow band field sensors. In 2001, two corn experiments were planted over an old manure experiment... |
7. Use of Chlorophyll Flourescence Techniques to Detect Stresses in CornIncreased efficiencies in the use of water and fertilizer will require better methods of monitoring crop stress. This study was conducted to determine whether chlorophyll fluorescence was more sensitive to detecting water and nitrogen stress than chlorophyll meters in corn (Zea mays). The experiment was carried out near Shelton, NE in 2000, 200 1, and 2002. Treatments consisted of a factorial combination of 12 corn hybrids (1 1 Pioneer Hi-Bred internationali and B73 x M017), two water levels (deficit... |
8. Nutrient Management Implications of Relay Cropping on the EnvironmentResidual nitrogen (nitrate-N) remaining in the root zone after seed corn production is frequently greater than under commercial corn production. This nitrate is subject to leaching into the shallow ground water of the Platte River Valley in South-Central Nebraska. as noted by elevated nitrate-N concentrations under seed cornfields compared to other fields. Hard-red winter wheat was planted into seed corn residue in early October of 2001 as a cover crop to scavenge residual- N from the root zone and... |
9. Relationship Between Response Indices Measured In-Season and at Harvest in Winter WheatCurrent methods for making nitrogen recommendations in winter wheat (Triticum aestivurn L.) do not adjust for in-season temporal variability of plant available non-fertilizer nitrogen (N) sources. The purpose of this study was to compare the use of different nitrogen response indices determined in-season @INDVI and RIPLANTHEIGkm) to the nitrogen response index measured at harvest (RIHARvEST). In addition, this study evaluated the use of the in-season response indices for determining topdress nitrogen... |
10. Active Sensor Orientation Over Corn Rows and Effect on Assessment of BiomassOur long-tern mresearch goal is to develop practical N application systems that use on-the-go remote sensing as a nleans to assess crop N status and only apply N where needed at times when the crop can most efficiently utilize N. Our preliminaty testing of two active sensor systems has shoxl-11 considerable promise for rapid and accurate assessment of canopy N status and crop biomass. In this work, the effect of sensor positioning and orientation over the canopy and their effects on assessment of... |
11. An Update on Crop Canopy Sensors for In-Season N ManagementRemote sensing in agriculture has focused 011 the spectral and spatial properties of plants. Remote sensing provides the capability for rapid collection of vast quantities of spatial data that can be analyzed quickly for use in detel-mining a course of action. This creates the potential for using remote sensing to assess and manage in-season production practices. Past research has shown that a change in canopy rel-lectance inay not be unique for a given stress. Also, other agents may have effects... |
12. In Season RecommendationsWe are testing a prototype high-clearance tractor configured with active crop canopy sensors, drop nozzles with electronic valves, and a variable rate controller as means to deliver in-season variable rates of liquid N fertilizer based on crop needs as an alterative to preplant uniform applications of N. The active sensor we're evaluating is the model ACS-210 Crop Circle made by Holland Scientific. It generates it's own source of modulated light in the amber and near infrared (NIR) bands and then... |
13. In-Season Nitrogen Recommendations for CornMaking fertilizer N recommendations involves a great deal of guess work and uncertainty because much, essentially all, of the fertilizer N is applied before the crop is planted and the amount is based on estimated crop use from historical data. In addition, producers, consultants, and fertilizer dealers try to anticipate how much N might be lost because of untimely or excess precipitation or how much additional N might be required if the weather conditions are favorable. Sidedress and in-season... |
14. Evaluation of Crop Canopy Sensors as a Tool for Soybean Research and ProductionDetermining the variables that consistently increase yields in soybean  [Glycine max (L.) Merr.] continues to challenge researchers, agronomists and growers alike. Crop canopy sensors have emerged as a technology used in other cropping systems to monitor and manage agricultural inputs. The sensors measure reflectance in selected wavebands that are used to calculate vegetation indices that relate to unique leaf or canopy characteristics. The objectives of this study were to determine if a commercially... |
15. Active-Crop Sensor Calibration Using the Virtual-Reference ConceptCalibration of laboratory and field instruments usually involves collecting data from some type of accepted standard materials or compounds. This approach works well for most physical and chemical measurements; however, such procedur es become problematic when dealing with biological systems like plants that go throug h a number of physiological states during the growing season. In addition, genetic composition differences between cultivars can affect the architecture of plant canopies a nd relative... |
16. Remote Sensing as a Tool for AgricultureThe tendency for nearlv everything in our society to be bigger, better, faster, easier, cheaper, and safer than in the past has resulted in many challenges. Agriculture is not immune from these trends, and in some cases agriculture even leads the way. Incorporation of remote sensing into site- specific management activities is one area where technologies are being merged to develop a new array of products that are intended to help producers and consultants make better and more timely management decisions.... |