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GreenSeeker Frequently Asked Questions
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Who is NTech Industries, Inc.?
NTech, an ag technology company formerly known as Patchen, holds numerous patents for active plant sensors. NTech markets the GreenSeeker® variable rate fertilizer application system and the WeedSeeker®, which uses similar technology to selectively spot spray weeds.
What is GreenSeeker®?
GreenSeeker® is an integrated optical sensing and application system that measures crop status and variably applies the crop's nitrogen requirements. Yield potential for a crop is identified using a vegetative index known as NDVI (normalized difference vegetative index) and an environmental factor. Nitrogen (N) is then recommended based on yield potential and the responsiveness of the crop to additional nitrogen.
The GreenSeeker® applies the right amount of N at the right place and at the right time thereby optimizing yield and N input expense.
How does the sensor work?
The sensor uses light emitting diodes (LED) to generate red and near infrared (NIR) light. The light generated is reflected off of the crop and measured by a photodiode located at the front of the sensor head.
What is NDVI?
Normalized Difference Vegetative Index (NDVI) is commonly used to measure plant health and vigor.
NDVI is calculated using the equation (NIRreflected - Redreflected)/(NIRreflected + Redreflected).
How does the sensor determine crop status?
GreenSeeker® calculates NDVI using red and NIR light. Red light is absorbed by plant chlorophyll as an energy source during photosynthesis. Therefore, healthy plants absorb more red light and reflect larger amounts of NIR than those that are unhealthy. NDVI is an excellent indicator of biomass (amount of living plant tissue), and is used in conjunction with growing degree days greater than zero (GDD>0) or days from planting to accurately project yield potential.
Why not use ambient light instead of an active LED light source?
Several problems exist when using the sun as a light source. The sun's intensity is affected by sun angle, cloudiness, haziness, etc., conditions which can cause inconsistent NDVI measurements. NTech developed an active sensor that generates its own illumination source to measure NDVI. In fact, the sensors function in nearly any condition including darkness, dramatically extending the application period.
Why is a nitrogen rich strip necessary?
Long-term research has determined that the amount of N required to achieve maximum yield varies significantly from year to year. Reducing pre-plant N application and using the N rich strip to establish a rich N environment allows a mid-season determination of additional N requirements. If the crop is capable of using additional N, the sensor will determine the magnitude and generate an N recommendation based on the predicted yield.
What is response index (RI) and how is it estimated?
RI is an in-season quantitative measure of the response to additional N for each field environment. Using the RT200 or a Handheld sensor, NDVI readings are collected from the nitrogen rich strip and the field rate to determine the benefit of additional N. To determine the response index we simply divide the NDVI from the N rich strip by the NDVI value of the field rate. This ratio provides an indication of how the crop will respond to additional N.
What N rate should be used in the N rich strip?
The rate for the nitrogen rich strip should be large enough to achieve the field's typical yield goal. This amount is crop and region dependent. For example, many winter wheat recommendations are based on an assumption that each bushel of grain produced requires 2 lbs. of N. Assuming a 40 bushel yield goal, an 80 lb. N recommendation is suggested. In this case, an N rich environment of 96 lbs (80 lbs x 1.2) of N should be applied.
What size strip should be used for the nitrogen rich strip?
The ideal strip would be an applicator boom width down the middle of the entire field. The N rich strip should be 300 to 500 feet long in a representative area of the field (not in a bottom, or an upland), or the N rich strip should run across several field "identifiable" management areas, such as different soil types or topography.
Does each field need an N rich strip?
Yes, to achieve optimal success, each field needs an N rich strip, just as conventional N management requires a soil sample from each field. The N rich strip integrates the effects of past field management, current field management (e.g. planting date, variety, etc.) and soil differences in the field on crop response to N. These factors often differ greatly from one field to another.
What other crops is NTech working on?
Algorithms have been developed for winter wheat, spring wheat and corn. . Researchers are also developing algorithms for potatoes, sugar beets, durum wheat, canola, barley, cotton, turf, and sunflowers.
What mapping capabilities does the system have?
GreenSeeker Application systems can produce a crop heath and vigor map with boom width resolution during fertilizer variable rate applications, or during any other farming operation. The pixel size determined by the boom width and ground speed. The system can produce "As Applied" maps (the amount of material applied) and "NDVI" maps. Using these maps, problem areas requiring other inputs and management decisions can be identified.
How are sensor readings taken of the N rich strip and the rest of the field?
The sensors on the RT200 boom can be used to take the N rich strip readings. This can be done with the three left or right sensors, or all sensors on the boom. The GreenSeeker Hand Held sensor can also be used to take the N rich strip readings.
What about leaf burn?
Top dress leaf burn can be an issue if a high rate of N is applied during periods of high temperature and humidity. NTech recommends using a streaming nozzle, or similar delivery system, to allow the solution to flow off of the plant, exposing only a small amount of plant tissue to possible burning. NTech recommends avoiding application when the plant tissue is wet and during the heat of the day. Remember, the system uses its own illumination source and can also function at night.
How is the N recommendation determined?
Sensor readings are used to measure both predicted crop yield potential, and crop response to additional N. These two factors, in addition to generally accepted N requirements per bushel, determine N recommendations and application rate.
Why do NDVI readings taken at different heights above the crop canopy remain constant? And, how does the sensor integrate a 24" wide area at different heights above the crop?
NDVI readings remain similar through the 32-48" range because the computation is actually a normalized ratio. Even though the intensity of the light source decreases as it moves farther away from the crop canopy, the sensor proportionally adjusts and therefore, NDVI readings are not affected by height variance. Also, optical masking and position of the sensor LEDs allows the sensor to view only a 24" wide strip regardless of the sensor height.
Does the sensor differentiate between weeds and the crop?
Today, the sensor does not differentiate between weed and crop species.
Can fertilizer and crop protection chemicals be applied simultaneously?
Yes. NTech's RT Commander software has an injection system option designed to allow the use of a secondary boom for flat rate application of liquid fertilizer as a "carrier" for the chemical, and use the sprayer's existing wet boom for variably applying N with the GreenSeeker®. The N solution used as the carrier fluid in the existing wet boom and is set at a low rate in comparison to the range of rate the GreenSeeker® system uses. This may require addition of additional rate control equipment.
When is wheat spraying recommended?
NTech recommends N application at the 5 to 6 leaf stage (Feekes 5, GS 30) for wheat. Corn should be V-8 to V-12.
Does the sensor work on dormant wheat?
If the crop is brown (no green pigment) the sensor does not have the ability to recognize yield potential. The crop must be green for the sensor to function.
Does system operation require GPS or yield maps?
GreenSeeker® can apply with or without the use of a GPS signal, and does not rely on historical information or mapping to make an N recommendation. The sensor system determines the yield potential and uses the response index from the field to determine a top dress N rateŠ. in-season and on-the-go. However, the mapping system of GreenSeeker® does require the use of GPS for data logging.
Can distinct management zones within the field be identified and used to determine response indexes for each zone?
Potentially. NTech's research has treated the field as a single unit to determine responsiveness to additional N and adjust N inputs based on yield potential variability in that field. The GreenSeeker® system generates outstanding results but further management zone research may prove useful.
Does soil affect the NDVI value? How does GreenSeeker® address the impact of bare soil?
Soil NDVI values are much less than a living plant. This relative difference is what allows the sensor to determine biomass accurately. Current wheat and corn algorithms require at least 50% of the 24 inch field of view of each sensor is covered by vegetation. Typically, 5 to 6 leaf wheat has reached adequate coverage to get a reliable reading. Corn should be V-8 to V-12.
What is the payback, and how long will it take to pay for the system?
This system has been proven to improve the grower's bottom line by $8-$10 dollars per acre in spring and winter wheat. Use of the RT200 system in 2004 corn trials showed an average increase in profit of $18 per acre. This increases resulted from improved yield and/or reduced N expense.
Payback is a function of the acres covered and how the system will be used. The payback period for a wheat grower farming 3000 acres with a 60-foot system is less than 2 years. . A custom applicator charging $3/acre more than the normal application charge can pay for a 90-foot system in less than two years if the machine covers 15,000 acres annually.
How long will it take to retrofit a sprayer?
If your sprayer has an exiting rate controller that can accept a serial rate command (very common), you can install the RT200 in about 4-6 hours.
Will the sprayer's existing control system work with GreenSeeker®?
Yes. The RT200 "talks" to many existing rate controllers with a serial connection between the systems.
How is the sprayer set up and the system utilized in the field?
The system needs the following information before application: planting date for Spring Wheat or corn, or growing degree days greater than zero (GDD>0) for Winter Wheat. Prior to running the sprayer the RT200 or a Handheld sensor is used to determine RI for the field. Once the RI is known, the decision to apply N is made. If the RI is 1 or less, no additional N is necessary.
Does dust affect the sensor reading?
Dust will not normally affect the NDVI readings because dust impacts the reflectance of red and NIR similarly. The RT200 system monitors the sensors for proper operation, if a sensor reports erroneous data, the data is not include in the calculation for fertilizer rate control.
The GreenSeeker® diagnostics will also provide a warning if a sensor is "blinded". The operator should wipe the sensor's lenses clean each time he/she checks the nozzles.
What type of GIS software is the map data compatible with?
The map data is output in a shape file format. The majority of GIS software will utilize this data format. Please refer to your specific GIS software for specifics on importing.
What if it does not rain after fertilizer application? Is the crop able to take up the N?
Moisture availability is a concern in all top dress application. However, if the N source used is UAN, a portion of the solution (nitrate) can move readily into the surface soil after application and be plant available quickly.
Nitrogen is cheap and it is less costly to apply more N rather than investing in a variable rate application system. Why not continue to use pre-plant N?
Anhydrous ammonia is inexpensive, approximately $0.28/lb., and it is often considered appropriate to apply 100 lbs. of pre-plant N (wheat) and ignore the in season crop N needs. Pre-plant application of N is extremely inefficient (~33%). Prior to the 5 leaf stage, wheat's N needs are small and high rate pre-plant application of N is potentially wasted because the crop will not use it. The unused portion of the N that remains in the soil is often lost before the crop is able to use it. This may result in N stress later in the growing season and, ultimately, yield losses.
The amount of N supplied by the soil is not well understood and unpredictable. The organic fraction of soil is a huge reservoir of N. In fact, 1% organic matter contains about 2,000 lbs. of N per acre. If the organic fraction of N is mineralized and made plant available, the need for supplemental N is reduced or precluded. The GreenSeeker® saves unnecessary expense by applying the optimum amount of N for the soil conditions, thus eliminating excess expense and alleviating environmental effects.
The yield potential for any crop in a specific environment is not known until the season is underway. If N was applied to generate a 50 bushel wheat crop but only 27 bushels are harvested, what happens to the rest of the N? Will it be available for subsequent crops? Maybe, maybe not, depending on the environment. If the soil was able to support 24 of those 27 bushels, how much N is needed? If 20 lbs. of N would have generated the 27 bushel yield and 100 lbs. pre-plant was applied (hoping for a 50 bushel year), then the grower spent an unnecessary $12/acre by over-applying N. This example demonstrates how expensive excess application can be.
How durable is the GreenSeeker® system in a fertilizer and ag chemical application environment?
GreenSeeker's® electrical system consists of electronic control units (sensors and control boxes) and wiring harnesses. Both elements utilize components that have been proven in harsh environments. The sensor uses the same housing as does NTech's WeedSeeker®, which has been marketed for years. This housing undergoes an intensive sealing and testing procedure during assembly, including pressurization and leak tests to ensure the unit is air tight.
The system's control boxes are NEMA 4X rated (industry standard), which ensures liquid free sealing characteristics. All wiring harnesses utilize highest quality connectors that are fully sealed. These connectors are commonly used on agricultural equipment, HD off-road equipment, and in many industrial applications that operate in harsh and/or difficult environments. NTech engineers made electrical security one of the leading design requirements and have delivered a durable and very reliable system.
What happens when a sensor hits a tree, fence post, or the ground?
It is inevitable that the boom will strike something during the spray season. The ideal approach would be to carry a spare sensor in the cab for emergencies. The sensor can be replaced in 15 minutes by removing two bolts and one or two cable connections. The damaged sensor should be sent to the company/distributor for repair. Frequently, only the housing will need repair, a minimal expense. NTech offers an extended 5 year service program on the sensors. If a sensor is not covered by the initial warranty program, the company will replace it for $500 regardless of failure reason.
The RT200 system monitors the sensors for proper operation, if a sensor reports erroneous data, the data is not include in the data used for fertilizer rate control.
Why purchase this system?
The GreenSeeker® system maximizes your return on investment in nitrogen. If ideal growing conditions promise a high yield, enough N is applied to achieve that yield. If the environment will not support a large yield, nitrogen will not be wasted. Testing has proven that GreenSeeker® generates $8 to $10 average return per acre on winter or spring wheat, and an $18 per acre average for corn. This is based on higher yields and/or reduced N expense. Research and field data also indicates that some years the savings would be double these numbers.
Placing a dollar figure on the environmental savings is difficult, but the impact that GreenSeeker® technology will have is immense. Pre-plant application of N is extremely inefficient (~33%), GreenSeeker® data suggests that over 50% nitrogen use efficiency is possible. Applying the correct amount of N, at the right place and at the right time will decrease excess application and alleviate ground and surface water contamination without reducing yield. GreenSeeker® technology can help ensure a better quality of life for growers, their families and the general population.
Will the government help?
Government incentives help make the GreenSeeker® system even more attractive. The Environmental Quality Incentive Program (EQIP) and the Conservation Security Program (CSP) included in the Farm Bill are geared to systems like GreenSeeker®.
The amount of money available to adopt new nutrient management technologies varies by location. Contact the local NRCS office to determine the exact monies available.
Where can more information be found or an order placed?
For additional information: contact us or call 1.888.728.2436.
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