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Sensor Based VRN Lamar09

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Published on January 29, 2009

Author: shannonkent

Source: authorstream.com

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Variable-Rate Nitrogen Fertilizer Application in CornUsing In-Field Sensing of Crop Canopy : 1 Variable-Rate Nitrogen Fertilizer Application in CornUsing In-Field Sensing of Crop Canopy Kent Shannon Extension Natural Resource Engineer Boone County Discussion Items : 2 Discussion Items Background and justification for variable-rate nitrogen application in corn Why use corn canopy or leaves for nitrogen management decisions Procedures for using sensors for determining nitrogen rate - leaf chlorophyll meter - canopy light-reflectance sensors Slide 3: 3 Contributed by Larry Hendrickson, John Deere Inc. Slide 4: 4 July Aerial Photo of a Missouri Corn Field Why is there a need for variable-rate nitrogen? : 5 Why is there a need for variable-rate nitrogen? Variation within fields of soil properties such as texture and organic matter Variable loss pathways (e.g., nitrification and leaching) Variable mineralization of soil nitrogen from organic matter Why is there a need for variable-rate nitrogen? : 6 Why is there a need for variable-rate nitrogen? Variation within fields because of non-uniform historic management (e.g., manure applications) Why is there a need for variable-rate nitrogen? : 7 Why is there a need for variable-rate nitrogen? Increased awareness of environmental problems and of lost profit associated with over application of nitrogen fertilizer What should the goal be? : 8 What should the goal be? Optimize profit Minimize over-applications that may harm the environment Why Crop Canopy of Leaves to Determine N Rate? : 9 Why Crop Canopy of Leaves to Determine N Rate? Nitrogen is a primary constituent of plant chlorophyll pigments and this is where photosynthesis takes place. Thus, leaf or crop canopy color can be used to evaluate crop N health. Provides site-specific indication of nitrogen need Assessment of fertilizer N need coincides with the time when crop N uptake is greatest (sometimes called “synchronization”) What can sensors measure? : 10 What can sensors measure? Crop Color - Of the visible light spectrum, the chlorophyll in the chloroplasts absorbs the red and blue wavelengths and reflects the green. Nitrogen deficient corn has less chlorophyll and reflects less green. It looks yellowish-green to our eyes and is measurable by the sensors. This is an indicator of a plant’s “photosynthetic” health. What can sensors measure? : 11 What can sensors measure? Crop Biomass – The non-visible near infrared (NIR) wavelengths are reflected by crop foliage and absorbed by soil. Thus, NIR energy can measure relative amounts of biomass. This is an indicator of a plant’s structural capacity to assimilate carbon. Procedures for Agronomy Technical Note MO-35 : 12 Procedures for Agronomy Technical Note MO-35 leaf chlorophyll meter active canopy reflectance sensors Step 1 for Both Sensors:Create a Sufficient-N Reference Area : 13 Step 1 for Both Sensors:Create a Sufficient-N Reference Area A sufficient-N reference area needs to be established before or shortly after planting. How to Do a Sufficient-N Reference Area : 14 How to Do a Sufficient-N Reference Area ~200 lbs N / acre at about planting For large, highly variable fields, best to create multiple reference areas or apply a strip across the field. Width of reference area must be wider than the sensor mountings on the fertilizer application rig to be used later. Flag the reference area. Slide 15: 15 Slide 16: 16 Sufficient-N Reference Area Slide 17: 17 Hybrid A Hybrid B Hybrids vary subtly in color, so each hybrid needs its own sufficient-N reference. Why A Reference Area? : 18 Why A Reference Area? The sensor-measured difference between this reference area and the corn to be fertilized at side-dress stage is the basis for how much nitrogen fertilizer is needed. Active Canopy Reflectance Sensors : 19 Active Canopy Reflectance Sensors Two different models: Holland Scientific Crop Circle ACS-210 Plant Canopy Sensor NTech Industries Inc. GreenSeeker These sensors measure visible and NIR reflectance and calculate vegetative indices. Sensors are mounted on the front of fertilizer applicators. Reflectance data is processed by a computer in the cab that prescribes the rate of nitrogen for the applicator controller. So, the crop sensing and variable-rate fertilization is done in one pass. Steps for Active Canopy Reflectance Sensors : 20 Steps for Active Canopy Reflectance Sensors Create a sufficient N reference area and mark the corners of the area. For fields with highly-variable soils, multiple areas or N reference strips positioned to capture this soil variability is recommended. Avoid areas that historically have had other management problems (e.g., heavy weed infestation, head-lands with soil compaction). The reference area needs to be wide enough to include all sensors when mounted on the fertilizer application equipment (typically 30 ft wide is sufficient), and a minimum length of 50 ft for a single area. Pre-plant or at Planting Steps for Active Canopy Reflectance Sensors : 21 Check sensors and mount on applicator The width of the variable-rate application should be considered when deciding how many sensors should be installed. A minimum of 2 sensors on 2 different rows are to be used for representing the applicator swath width. Mount sensors so that they will be level and directly aligned over corn rows. Distance from the sensors to the crop canopy should be from 24 to 36 inches. Test the system for appropriate delay settings and calibrated for the targeted application rates. Ensure that the equipment is capable of delivering the range of N rates likely required and at the speed of field operations. At Side-Dress Steps for Active Canopy Reflectance Sensors Steps for Active Canopy Reflectance Sensors : 22 Sensor Measurements on Sufficient N Reference: At the time of side-dress N fertilization, sensor readings are first taken from the sufficient-N reference corn. Reference values are used to compute N recommendations. At Side-Dress Steps for Active Canopy Reflectance Sensors Steps for Active Canopy Reflectance Sensors : 23 Sensor Measurements and Application: The applicator then drives over the rest of the field sensing, calculating, and applying N variably, all in one pass. At Side-Dress Steps for Active Canopy Reflectance Sensors Slide 24: 24 * The value of the ratioreference should not exceed 0.28. Set this as a ceiling. ** With all equations, maximum N rate should not exceed 220 lbs N/acre. Calculation for N fertilizer Rate Greenness of Corn at Side Dress6/3/04 – Miami, MO : 25 Greenness of Corn at Side Dress6/3/04 – Miami, MO Reference strip with 150 lbs N at planting Target strip for side dress Average of 175 lbs N/ac applied Slide 26: 26 Anhydrous ammonia Fluid Dry Slide 27: 27 Sensors Mounted on Producer Rig Applying UAN + Agrotain Sensor Active Canopy Reflectance Sensors– Handheld Mode : 28 Active Canopy Reflectance Sensors– Handheld Mode These canopy sensors can be set up to work in a hand-held mode (see manufacturer’s information) and measurements electronically recorded while walking next to a corn row. If used in this way, follow instructions for management zones as described with th chlorophyll meter. Operation of these sensors in hand-held mode is not ideal for collecting site-specific information for variable-rate N applications in large production fields. Slide 29: 29 Note the Within-Field Variability of Corn Greenness Fields and Situations Most Suited for Sensor-Based Varible Rate Nitrogen Applications : 30 Fields and Situations Most Suited for Sensor-Based Varible Rate Nitrogen Applications Fields with extreme variability in soil type (e.g., flood-plain soils) Fields experiencing a wet spring or early summer (loss of applied N) and where additional N fertilizer is needed Fields that have received recent manure applications, due to uncertainty in how much N is available from the manure Fields receiving uneven N fertilization because of application equipment failure Fields coming out of pasture, hay, or CRP management Fields of corn-after-corn, particularly when the field has previously been cropped in a different rotation Fields following a droughty growing season (i.e. non-uniform carry-over of soil N after the drought year) Points and Risks to Consider : 31 Points and Risks to Consider Procedures require a familiarity with sensor data collection and variable-rate controllers. Use application and control systems that will match the desired range of variable-rate N application. Do not use these sensors and procedures before the corn is 1 ft tall. Many soils will need some N fertilizer for early growth. This can be added with P fertilization (MAP or DAP), starter fertilizer, manure additions, or other pre-plant fertilizer operations. For low to medium productive soils, 30 to 40 lbs is usually sufficient. High productive fields should be fertilized with 40 to 60 lbs N/acre. More than 60 lbs N/acre early, and one runs the risk of not being able to accurately detect additional need using the sensors. Points and Risks to Consider : 32 Points and Risks to Consider Unless high-clearance equipment is used, only a narrow window of time (~2 to 3 wks) is typically available for doing N applications in knee- to waist-high corn. The potential for extended periods of inclement weather need to be considered when determining how many acres can be covered by a fertilizer applicator. Surface-applied side-dress N will not generally be available for plant uptake until precipitation moves the N into the root zone, a risk that should be considered. A volatilization inhibitor should be considered when side-dressing urea-based N fertilizer on the surface. Slide 33: 33 Two Commercial Companies With Technology Available for Sensor-Based Nitrogen Application Slide 34: 34 You Need a Variable-Rate Compatible Controller Will Have A 9-pin Connector Slide 35: 35 Sensor And Mounting Hardware Interface Module VR Controller Pocket PC Computer with RTCommander Software DGPS Receiver Example of a RT200 N-Tech GreenSeeker System Crucial Step – Setting Up RTCommander Software : 36 Crucial Step – Setting Up RTCommander Software Communication Ports GPS Variable Rate Controller GreenSeeker Sensors Nitrogen Application Algorithm Involves Setting Up a Look Up Table to implement University of Missouri’s Algorithm On-farm sensor demos 2004-2007 : On-farm sensor demos 2004-2007 Forty-one demonstration fields All had a replicated comparison between producer rate and sensor rates applied at sidedress On-farm sensor demos 2004-2007 : On-farm sensor demos 2004-2007 On-farm sensor demos 2004-2007 : On-farm sensor demos 2004-2007 On-farm sensor demos 2004-2007 : On-farm sensor demos 2004-2007 On-farm sensor demos 2004-2007 : On-farm sensor demos 2004-2007 On-farm sensor demos 2004-2007 : On-farm sensor demos 2004-2007 On-farm sensor demos 2004-2007 : On-farm sensor demos 2004-2007 Sensor Benefits: : Sensor Benefits: Make sure enough N is applied Avoid unneeded N application Slide 47: N application to head-high corn N rate map June 20, 2007 Sensor Benefits: : Sensor Benefits: Make sure enough N is applied Avoid unneeded N application Slide 52: August 1 Aerial Photo after the June 13 UAN Application Questions : 54 Questions

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