Title: Developing Management Zones to Target Nitrogen Applications

PERROTIS COLLEGE

AMERICAN FARM SCHOOL, THESSALONIKI, GREECE

(Degrees validated by

Cardiff Metropolitan University, UK)

Module title/Code: Precision Agriculture GRK319U

Level and semester: Level 2, Semester 3, Autumn 2012

Module leader: Dr. Athanasios Gertsis

Module instructor: Dr. Athanasios Gertsis

Student: Eugeniu Cozonac

Research Project (100% of final grade-max words=3000) - Word

count: 2644

Title: Developing Management Zones to Target Nitrogen

Applications

Precision Agriculture 2012

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Declaration of plagiarism:I certify that this assignment is a result of my own work and it has not been submitted in whole

or major parts of it in any other module. All sources have been acknowledged.

Student: Eugeniu Cozonac

Signature:

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Table of Contents

SUMMARY____________________________________________5

INTRODUCTION ____________________________________________6

WHAT IS PRECISION AGRICULTURE (PA)?____________6

PROJECT OBJECTIVE_________________________________7

PRECISION AGRICULTURE AND VARIATION IN THE SOIL________7

WHERE DOES THE NITROGEN COMES FROM___________________________8

MINERAL SOURCES OF NITROGEN____________________________9

MINERAL FERTILIZERS _____________________________________11

WHAT IS SENSOR-BASED, VARIABLE RATE NITROGEN MANAGEMENT__________11

ENSURING SPREADING PRECISION__________________________________12

REDUCING FERTILIZERS INPUT BY SENSOR CONTROLLED SPREADING___________13

REDUCING SOIL ACIDIFICATION__________________________________15

CONCLUSIONS__________________________________15

REFERENCES_______________________________________________16

APPENDICES ________________________________________________18

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SUMMARY

To determine soil nitrogen (N) or the potential soil yield,management’s zones for N fertilizer management nowadays offers alarge gamma of possibilities using different tools such astopography, satellite imagery, aerial photographs, soil electricalconductivity sensor, yield maps and intensive soil survey data. Agood start for a farmer management, the satellite images and aerialphotos which somehow may be the cheapest way comparing to othermethods (in US case). The direct measurement in yield variationfrom space has been available to farmers since 1990s. Finding outyield variation over a certain a field makes easier to determineand estimate the variable-rate N and as well other nutrientapplications, but as well to mention that yield maps may become notclear enough many potential causes of yield variability and as wellas errors.

Using only yield maps in order to make anestimation crop production for nutrientmanagement by not taking intoconsideration measuring other potentialfactors as temporary yield-limitingfactors such as pest incidence makes anwaste of time, resource and effort tomake a precision estimation (Goulding &Whitmore 2008).

Generally more than one layer of information is required to findout comparison data and similarities among patterns in order to

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find nutrient management areas. Furthermore is a right reason for Npatterns to exist in fields and as well to have these patternsstable during some years. ’’Zones can be constructed and managedfor N using a fraction of the number of soil samples required toreveal the same zones through grid sampling’’ (Franzen & Kitchen2008). Zone sampling therefore creates opportunities for farmer toachieve lower sampling costs for the variable rate of fertilizerthat have to be applied and increases the rate of precision farmingto be more convenient for producers of commodity crops.

After this step the next one would be to develop computer models toautomate the zone development process and furthermore reviewingseveral maps in order to create and draw zone boundaries (Franzen &Kitchen 2008).

INTRODUCTION

What is Precision

Agriculture (PA)?

Taking into consideration thefact of continually growingworld population, increasing theinputs of nutrients in lastdecades is considered as asolution of increasing thesupply food. Nutrient managementin agriculture plays significant

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role. For many years farmers knows that they need to replacenutrients removed in crop plants to maintain an appropriatenutrient balance by keeping the soil fertile. Before thefertilizers were widely available, farmers could observe adeficiency of nutrients in their soils were thereby yields ofcrops such as wheat were smaller than actually using fertilizers.Later on the produced fertilizers proved to be effective in manyexperiments such as Rothamasted’s one , were thereby resulted inlarger quantity yields. The Rothamasted’s experiments (Rasmussen& Goulding & Brown & Grace & Janzen & Korschens 1998) provedthat the use of fertilizers increases yields by two or three timein comparison with the fields that were not using fertilizers(figure 2 shows fertilizers increasing use). Nowadays nutrientmanagement became a globally critical part of the agriculturaleconomical and social sustainability. The important nutrientsNitrogen, phosphorus, potassium, calcium and magnesium, sulphur,trace elements (Goulding & Jarvis & Whitmore 2008). Nitrogen isrecognized as ’’pillar of the fabled Green Revolution’’ due tothe fact that largely used as fertilizer avoided the globalfamine in 20th century (Nooteboom 2003; Franzen, & Kitchen 2008).

Furthermore taking into consideration the most importantnutrients, like nitrogen (N), in various cases caused nutrientimbalances, the surplus use especially of N, incompetent use andas well large damages to the surrounding environment by impact onwater quality human health, biodiversity and air. Therefore thereis a need of precise management use of nitrogen. A comparativelybetter management of all important nutrients is requiredtherefore to maintain the required increases in food productionwhile at the same time to minimizee environmental impacts, wasteand last economic loss. The land manager is the one responsibleof nutrients management, and the one from whom by using different

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decision methods for calculating rates of application in order tomake an estimation of yield production targets (Goulding & Jarvis& Whitmore 2008).

2.2. Project objectives

The objective of this study is to present the benefits ofVariable Rate Application for Nitrogen fertilizers. Anotherobjective is describing the importance of using precisemanagement use of fertilizers which contrary may be an importantfactor of pollution from agricultural sources e.g. by phosphorusor nitrogen (Vall & Vidal 2006).

2.3. Precision Agriculture and Variation in Soil

Nitrogen

Grid sampling is one of the methods that are often thereforeconducted by using specific site-specific sampling for soilnutrients. Grid sampling is a regular sample that is perfectlyused at a high and large scale so that standing fertilitypatterns and levels of these patterns are replicated. Gridsampling is largely used due to the impartial approach that doesnot adopt a correlation of fertility patterns with any moreeasily definite field attribute. To continue Nitrogen sampling isdiverse than sampling of phosphorus (P), potassium (K), and soilpH. Due to chemical transformation and due to N mobility in thesoil there is a need of sampling the soil each year that N isapplied. As well Nitrogen is achieved to a deeper depth (from 1to 6 feet), but this many times tightly depends on the crop andsoil area that was sampled. Consequently the cost of gridsampling besides the time to sample stands frequently much higher

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as well as cost high-priced once compared to sampling fornutrients requiring only a 0 to 6 inch core. On the other hand,various studies have proved that soil N levels are oftencorrelated to soil category and/or landscape position, whichprimarily leads to the usage of management zones to direct ortarget sampling (Franzen & Kitchen 2008; Cain & Evans 1999).Additional measurements as well as observations, together withsoil electrical conductivity sensors, aerial photographs, yieldmapping, and satellite imagery, as well as detailed knowledge ofsoil series, can be useful and helpful in defining managementzones like in N availability. “Correct grouping of areas beforesoil sampling can reduce the number of soil samples needed andhelp make sampling a cost-effective tool in creating a map of Nvariability and in developing a variable-rate N plan .” (Franzen& Kitchen 2008).

Where does the nitrogen come from?

The main sources of nitrogen input to agricultural land comefrom mineral fertilizer or livestock manure. In addition thereare several extra inconsequential sources of nitrogen to soils,for instance deposition of nitrogen in addition with ammonia fromthe atmosphere, nitrogen fixed in a biological way by crops suchas leguminous plants, besides these the other source is spreadingon land the sewage waste. On average these sources accounts fora lesser percentage of nitrogen inputs associated with livestockmanure and mineral fertilizers (Vall & Vidal 2006; Bohlool, &Ladha & Garrity 1992). In 1995, mineral fertilizers was of 50%and more of overall nitrogen use in Denmark, Germany, Greece,France, Luxembourg, Finland as well as Sweden. On contrary in

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Belgium and the Netherlands livestock manure remained main inputfor more than 50% of nitrogen inputs (Figure 1) (Vall & Vidal2006).

Source: (Vall & Vidal 2006)

Mineral sources of nitrogen

In the European Union countries mineral as commercialfertilizers are used to agricultural lands mostly as directsource of nitrogen fertilizers in the form of ammonium nitrate.Nitrogen in commercial fertilizer is predominantly soluble toenhance absorption by crops; nevertheless this as well comes at

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http://ec.europa.eu/agriculture/envir/report/en/nitro_en/fig1.htm


risk to run away after heavy and dense rainfall and percolatingto groundwater (Vall & Vidal 2006). As European farmersconventionally count on on ammonium nitrate by means of the bestcompetent nitrogen source, the other additional sources as ureaand UAN are as well considered. Important point is that differentsources of mineral nitrogen in fact do not come together orinteract with the soil in the same way. These variations have tobe considered while assessing agronomic and environmentalperformances (Yara 2011). Nitrogen is claimed by many researchersas a vital element source of life. Nitrogen stimulates plant’sroot growth and photosynthesis, also for up taking of furthernutrients.

Ammonia can be applied to the field in a straight way such as afertilizer, or usually, it is altered into a different composite,equally with ammonium nitrate, diammonium phosphate, UANsolution, or urea and then used as a fertilizer (figure 1).

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Figure 2 names some particular uses for ammonia as well as thecomposite affiliations between several ammonia-derived products.(Kramer 2004).

Nevertheless, 99 % of the nitrogen on earth is found in theatmosphere and a reduced amount of 1 % is in the earth’s shell.The 99 % of nitrogen molecule (N2) in the atmosphere arechemically inactive and therefore are marginally easy to beabsorbed by plants. The lesser extent of reactive nitrogen inthe soil decrease biomass production in usual ecological unit.Agriculture still lessens reactive nitrogen from the soil.Theoretically, nitrogen is absorbed for the duration of plantgrowth and after removed from those fields through harvesting.In order to balance these deficits of nitrogen there is a need ofrestoring organic or mineral sources of nitrogen. Fertilizers,used and applied as manure or as mineral nitrogen, areconsequently a basic part of sustainable agriculture. Deficiencyof nitrogen consequences in decreasing soil fertility, and as

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well influences in decreasing yields and furthermore crop quality(Kramer 2004; Yara 2011). Or a further understanding Appendix 1.Bindicates nitrogen cycle.

Mineral fertilizers

This brochure assesses the effectiveness and side effects ofthe main mineral sources of nitrogen that are used in Europe:

• “Ammonium nitrate (AN) contains nitrogen -as NH4+ (ammonium)and as NO3 (nitrate) in equal portions. Calcium ammonium nitrate(CAN) contains in addition dolomite or limestone.

• Urea contains nitrogen in its amide (NH2) form.

• Urea ammonium nitrate (UAN) is an aqueous solution of urea andammonium nitrate. Conclusions for specialty produces, such asNPKs or sulphur containing products, even if not specificallymentioned, can be easily derived from general observations” (Yara2011). Appendix 1.D. indicates different forms of nitrogen forgarden management and as well further indicates a comparisonNitrate comparing to Urea, ability of absorption by plant.

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Source: Yara 2011

What is sensor-based, variable rate nitrogen

management?

Emphasizing on high production costs, it highly importantfor farmers to decrease crop inputs and at the same time toincrease yields by being competitive on market. The cost ofnitrogen is more or less at the same price with crude oil. Toestimate the nitrogen fertilizer is about 10% to 15 % of totalcosts for cotton, corn, and wheat in the Southeastern UnitedStates. The existence of nitrogen use is frequently inconstantfor farmers due to dissimilarities in topography and as well thesoil properties in a certain field. Thus, a sensor-based,variable-rate nitrogen application (SVNA) system by time wasdeveloped to decrease production expenses. The SVNA system inorder to be efficient it measures the field variability andafterwards regulates the nitrogen side dressing proportionsapplying N solicitations once already planted. In order to adjustcorrectly SVNA, farmers have to do a High Nitrogen CalibrationStrip or HNCS. The HNCS allows farmers to fix by reporting thenitrogen prominence of plants. Distinct HNCS might be fixed indiverse regions of a field as an optional way, nevertheless issuggested having in a fields a high variability in yields or soil

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properties as simple as organic matter or texture ranks. Regionsof a certain field might be noticed depending mainly on producerunderstanding of yields, computerized yield mapping, or else assoil established mapping procedure (Porter & Khalilian & Dourte &Fraisse 2012). ’’An index called normalized difference vegetationindex (NDVI) is used to help estimate plant N status. NDVI can bemeasured with optical sensors, and is a proxy for greenness andcanopy cover’’ (Porter & Khalilian & Dourte & Fraisse 2012).

Appendix 1.F illustrates a more detailed explanation how SVNAsystem is working.

Inexpensive, GPS-based equipment can be easily modernized onproducer of fertilizer spreading machinery for controllingnitrogen rate to meet crop necessities centered on NDVI of thecrop (Figure 3), NDVI of the yield in the HNCS zone, as well asthe N-application instructions of the SVNA . Clemson Universityscientists technologically advanced an SVNA method that usingGreenSeeker® optical sensors estimates side-dress nitrogennecessities for corn and cotton (Figure 3; Porter & Khalilian &Dourte & Fraisse 2012).

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Source: (Porter & Khalilian & Dourte & Fraisse 2012)

Ensuring Spreading Precision

Even spreading assures optimum nutrient supply. Ammonium nitrate,due to a higher bulk density and lower nitrogen concentration,offers more homogeneous spreading characteristics than urea. Windcan further degrade spreading homogeneity with urea, resulting insignificant local over or undersupply.

A study, conducted in Germany, compared the spreading loss ofurea to calcium ammonium nitrate. The results are shown in thecharts below. Even with a spreading width of only 21 meters, amild breeze of 4 m/s resulted in 26 % variation of applicationrate with urea, whereas it was only 6 % with CAN! A spreadinginaccuracy of 26 % is typically associated to yield losses of 2 %for winter wheat. Larger spreading width result in even higherlosses. Lower spreading width increases work load and reducesstrike force. (ref. 7) (Yara 2011).

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Reducing fertilizer input by sensor controlled

spreading.

Tools used in precision agriculture do increase the highspreading accuracy. One of the tools offered by the Yara N-SensorTM helps farmers to enhance a high control on spreadingfertilizers and GPS assessing criteria of nutrient supply. Thenitrogen deficiency on a specific plant field is measured allthrough spreading. As Yara N-SensorTM company states, it islargely used for spreading uniformly nitrate fertilizers whichtherefore assures a high yield by lowermost nitrogen input. Theefficiency was checked by more than one hundred fields applicantswhich therefore used to compare the N-sensor into farming,representing an comparable increase in protein apportion in 0,2-1,2 % and comparable increase in yield by 7% as well as a

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decreased input of nitrogen by 12%. (ref. 5) (Yara 2011).Appendix 1.C. indicates a more detailed answer on enhancingfertilizer efficiency and at the same time matching mineralfertilizers application with plant needs, while Appendix 1.E.indicates a measured biomass variation map, fertilizerapplication map, split N-aaplication N-Sensor and YARA N-Sensorat work.

Source: (Yara 2011)

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Source: (Gurian-sherman & Gurwick 2009)

Reducing soil

acidification

On the other hand nitrogenfertilizers on somespecific soils may playacidic effect, whichtherefore requests to beequilibrated in rightproportion by calciumhydroxide. Spreadingmineral fertilizers withhigh nitrogen efficiency decreases acidification as well asliming necessities. Mineral fertilizers as calcium ammoniumnitrate consist of limestone or dolomite, which therefore cutscost 2 to 58 % of spreading nitrogen. Figure 16 refers to ahandled tool that therefore provides information on actualnitrogen need of plant (Yara 2011; Hope & ZHU & Gries & Oleson &Kaye & Grimm & Baker 2005).Source: Yara 2011

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CONCLUSION

Taking into consideration the importance of precision agriculture

the agriculture all over the world shows an important step in

developing new technology for increasing soil proficiency as

yield and sustainable environment. Continuing on the topic of

’’Developing Management Zones to Target Nitrogen Applications’’,

the N-Sensors indicator shows an increase in benefits for

farmers. The important key the N-Sensors contribute is of

improving efficiency of nitrogen fertilizer, as saving costs and

as well very important to conform to environmental legislation.

Another important benefit is of more homogeneous crop as

increasing yield quality and at the same time faster harvesting.

The third important benefit is saving on agro-chemicals and

flexibility and control in terms of: independent of weather.

7. REFERENCES

References:

Andrews, G 1998, Gardening And Water Quality Protection: Understanding Nitrogen Fertilizers, Oregon State University, Viewed date 29 November2012, < http://www.oregon.gov/ODA/pest/docs/pdf/96_26_ec1492.pdf>.

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Bohlool, B.B. & Ladha, J.K. & Garrity, D.P. 1992, Biological nitrogen fixation for sustainable agriculture: A perspective, Plant and Soil, Vol. 141 , no 1-11, pp. 3-7.

Cain, ML & Evans, JP 1999, Sampling Spatial And Temporal Variation In Soil Nitrogen Variability, Oecologia, Viewed date 20 November 2012, <http://www.bowdoin.edu/faculty/m/mcain/pdf/oecologia-118-1999%20%208.pdf>.

Franzen, D.W. & Kitchen, N.R 2008, Developing Management Zones To Target Nitrogen Applications, North Dakota State University & Universityof Missouri- Columbia, Viewed date 15 November 2012, <http://www.ipni.net/publication/ssmg.nsf/0/A5CD47480DAF17D1852579E500765D7B/$FILE/SSMG-05.pdf>.

Goulding, K, Jarvis, S & Whitmore, A 2008, ‘Optimizing nutrient management for farm systems’, Philosophical Transactions of the Royal Society B, vol. 363, pp. 667-680.

Gurian-sherman, D & Gurwick, N 2009, Prospects Of Reducing Nitrogen Fertilizer Pollution Through Genetic Engineering, Union Of Concerned Scientists, Viewed date 28 November 2012, <http://www.ucsusa.org/assets/documents/food_and_agriculture/no-sure-fix.pdf>.

Hope, D, J & ZHU, W & Gries, C & Oleson, J & Kaye, J & Grimm, NB & Baker, LA 2005, Spatial Variation In Soil Inorganic Nitrogen Across An Arid Urban Ecosystem, Urban Ecosystem, Viewed date 20 November 2012, < http://larrybakerlab.cfans.umn.edu/files/2011/07/hope-et-al-spatial-var.-soil-inorganic-N-Urban-Eco.-2005.pdf>.

Kramer, DA 2004, Mineral Commodity Profiles Nitrogen, USGS, Viewed date 24 November 2012, <http://pubs.usgs.gov/of/2004/1290/2004-1290.pdf>.

Nooteboom, G 2003, Social Security And Livelihood In Upland East Java A Matter Of Style, Nijmegen, Indonesia.

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Porter, W & Khalilian, A & Dourte, D & Fraisse, C 2012, AgriculturalManagement Options For Climate Variability And Changes: Sensor –Based, Variable-Rate Nitrogen Management, University of Florida, Viewed date 29 November 2012, <http://edis.ifas.ufl.edu/pdffiles/AE/AE48700.pdf>.

Rasmussen, P.E. & Goulding K.W.T. & Brown J.R. & Grace P.R. & Janzen H.H. & Korschens M. 1998, Long-term agroecosystem experiments: assessing agricultural sustainability and global change. Science, vol. 282, pp. 893-896.

Sijpke, G & Raijmakers, W & Piecha, S 2012, Optimizing Fertilizer Application By Near-Sensing-Yara N-Sensors, YARA, Viewed date 28 November 2012, < http://www.fotonica-evenement.nl/assets/Fotonica-2012/Presentaties-27-maart/Yara-N-Sensor-Gerard-Sijpkens-Winfried-Raijmakers-en-tec5-Steffen-Piecha-PDF-AKKOORD.pdf >.

Vall, MP & Vidal, C 2006, Nitrogen in Agriculture, Agriculture and Environment, Viewed date 20 November 2012, < http://ec.europa.eu/agriculture/envir/report/en/nitro_en/report.htm >.

Yara 2011, Nitrate Fertilizer, Yara Nitrate Fertilizer, Viewed date 20 November 2012, < http://www.yara.com/doc/33521_Nitrate_-_Pure_Nutrient.pdf>.

Yara 2012, Yara Fertilizer Industry Handbook, Yara, Viewed date 28 November 2012, < http://www.yara.com/doc/37694_2012%20Fertilizer%20Industry%20Handbook%20wFP.pdf>.

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8. APPENDIXES

APPENDIX 1. A

Nitrogen transformations in the soilNitrogen undergoes transformations in the soil, depending on the chemical composition of the nitrogen applied. While nitrate is taken up directly by plants, ammonium and urea need to be first transformed into nitrate. Transformation losses are lowest with nitrate and highest with urea.

1 Application of fertilizers, containing mineral nitrogen as urea, ammonium, nitrate or a mix. Organic fertilizers and manure contain mostly complex organic nitrogen compounds and ammonium.

2 Uptake of nitrate is rapid due to the high particle mobility. Most plants therefore prefer nitrate over ammonium.

3 Uptake of ammonium is slower than nitrate. Ammonium is bound to

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clay particles in the soil and roots have to reach it. Most of the ammonium is therefore nitrified before it is taken-up by plants.

4 Nitrification by soil bacteria converts ammonium into nitrate in between a few days and a few weeks. Nitrous oxide and nitric oxide are lost to the atmosphere during the process.

5 Denitrification is favored by lack of oxygen (water logging). Soil bacteria convert nitrate and nitrite into gaseous nitrous oxide, nitric oxide and nitrogen. These are lost to the atmosphere.

6 Immobilization transforms mineral nitrogen into soil organic matter. Activity of soil microbes is mainly stimulated by ammonium. Immobilized nitrogen it is not immediately available for plant uptake, but needs to be mineralized first. Mineralization of soil organic matter (and manure) releases ammonium into the soil.

7 Hydrolysis of Urea by soil enzymes converts’ urea into ammoniumand CO2 gas. Depending on temperature, hydrolysis takes a day to a week. The soil pH around the urea granules strongly increases during the process, favoring ammonia volatilization.

8 Ammonia volatilization occurs when ammonium is converted to ammonia and lost to the atmosphere. A high soil pH level favors conversion of ammonium to ammonia. If conversion takes place at the soil surface, losses are highest. These two conditions are met when urea is spread and not immediately incorporated.

9 Leaching of nitrate occurs mainly in winter when rainfall washes residual and mineralized nitrates below the root zone. Accurate fertilization prevents leaching during the growth period.

Source: Yara 2011

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Figure 3: Transformation of urea, ammonium and nitrate in thesoil. Urea suffers the highest transformation losses, nitrate thelowest. UAN, a 50/50% mix of ammonium nitrate and urea, undergoes

the same transformations and losses as its components.

Source: Yara 2011

APPENDIX 1.B

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Source: Kramer 2004

Appendix 1.C

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Source: Yara 2011

Appendix 1.D of 31


Source: Andrews 1998

Source: Yara 2012

Appendix 1. E

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Source: Sijpke & Raijmakers & Piecha 2012


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Appendix 1. F

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The SVNA system works as follows:

1.Typical pre-plant N rate of 30 lbs/ac is applied to the cropacross all management zones.

2.HNCS is established in each part of the field management zone,where the producer wants to manage nitrogen separately.Management zones can be developed from the farmer’s knowledge ofthe field, aerial photos of the field available from onlinesources, maps showing the variability of soil electricalconductivity or yield, topography, soil water monitoring, andother relevant information.

3.At the time of nitrogen side-dress, optical sensors firstmeasure the (NDVI) of the HNCS in each management zone and thenmeasure the NDVI of the plants from the corresponding zones forcomparison.

4. Using the NDVI readings, a mathematical formula within thecontrol system calculates N requirements based on an in-seasonestimate of potential yield as predicted by the N algorithm. TheN algorithm also calculates the yield response to additionalnitrogen fertilizer and the required nitrogen rate for obtainingthe calculated yield. Depending on the type of equipment theproducer uses, the N application rate may be calculated in real-time and the SVNA controller would apply N at the same time. Ifproducers do not have a controller linked with the NDVI system,then they would collect NDVI data in a separate operation,process it to obtain the required nitrogen rate, and import anapplication map to their SVNA.

Source: Porter & Khalilian & Dourte & Fraisse 2012

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Title: Developing Management Zones to Target Nitrogen Applications

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