The feasibility of using optical sensors and non-nitrogen limiting reference crops to determine post-emergent nitrogen fertilizer requirements of canola was evaluated. Normalized difference vegetation index was well suited for estimating yield potential and nitrogen status. Although sensor-based nitrogen management was generally agronomically feasible for canola, the economic benefits of doing so remain uncertain because of the added cost of applying post-emergent nitrogen.

The popularity of variable-rate technology (VRT) has grown. However, the limitations and errors ofthis technology are generally unknown. Therefore, a spatial data model was developed to generate "asapplied"surfaces to advance precision agricultural (PA) practices. A test methodology based on ASAEStandard S341.2 was developed to perform uniform-rate (UR) and variable-rate (VR) tests to characterizedistribution patterns testing four VRT granular applicators (two spinner spreaders and two pneumaticapplicators). Single-pass UR patterns exhibited consistent shapes for three of the applicators with patternsshifts observed for the fourth applicator. Simulated overlap analysis showed that three of the applicatorsperformed satisfactorily with most CVs less than 20% while one applicator performed poorly (CVs andgt;25%). The spinner spreaders over-applied at the margins but the pneumatic applicators under-appliedsuggesting a required adjustment to the effective swath spacing. Therefore, it is recommended that CVsaccompany overlap pattern plots to ensure proper calibration of VRT application.Quantification of the rate response characteristics for the various applicators illustrated varying delayand transition times. Only one applicator demonstrated consistent delay and transition times. A sigmoidalfunction was used to model the rate response for applicators. One applicator exhibited a linear responseduring a decreasing rate change. Rate changes were quicker for the two newer VR control systemssignifying advancement in hydraulic control valve technology. This research illustrates the need forstandard testing protocols for VRT systems to help guide VRT software developers, equipmentmanufacturers, and users.The spatial data model uses GIS functionality to merge applicator descriptive patterns with a spatialfield application file (FAF) to generate an 'as-applied' surface representing the actual distribution ofgranular fertilizer. Field data was collected and used to validate the "as-applied" spatial model.Comparisons between the actual and predicted application rates for several fields were madedemonstrating good correlations for one applicator (several R2 andgt; 0.70), moderate success for anotherapplicator (0.60 andlt; R2 andlt; 0.66), and poor relationships for the third applicator (R2 andlt; 0.49). A comparison ofthe actual application rates to the prescription maps generated R2 values between 0.16 and 0.81demonstrating inconsistent VRT applicator performance. Thus, "as-applied" surfaces provide a means toproperly evaluate VRT while enhancing researchers' ability to compare VR management approaches.

In the recent past precision farming has become increasingly popular amongfarmers. However, little has been done to study the business aspect of precision farming,with most research focusing on the production side. This purpose of this thesis is tostudy the feasibility of successfully opening and operating a precision farming firm inKentucky. To determine the feasibility of such a venture a computer model was createdand a producer survey was designed and distributed to farmers in Western and CentralKentucky.The purpose of the computer model was to determine the factors that wouldinfluence the successful operation of a precision farming firm including number of acresserviced per year, pricing of services, the cost of capital to borrow money, and manyother factors. A break-even analysis was performed to determine what kind of annualincreases in business would be required, what price range services should be in, and atwhat interest rate money could be borrowed and a simulated precision farming firm couldstill operate successfully.The producer survey was mailed to 336 farmers in Western and Central Kentuckybecause of their geographical locations and the type of crops that are grown there. Thesurvey response rate was 20 percent and of the 66 surveys that were returned 59 wereappropriate and useful for research. After compiling the results of the surveys,regressions were run to determine any correlation between dependent and independentvariables that affect the adoption rate of precision farming techniques. The results foundthat a negative correlation exists between age adoption rates of precision farming and thata positive correlation exists between farm size and adoption rates of precision farming.After conducting the research, it is believed that given the right economicconditions and management a precision farming firm is very capable of thriving inKentucky. However, the workforce must be very motivated and capable of constantlyrecruiting new clients to adopt precision farming.

A field experiment initiated in spring 2012 was established to assess the relationships between grain yield, grain protein and soil properties including elevation, electrical conductivity, pH, and organic carbon in an undulating landscape. Grain protein can reflect the balance of nitrogen (N) relative to other yield limiting factors. The objective of this study was to 1) assess relationships between soil properties, crop yield and protein content in an undulating landscape in south-central Saskatchewan, and 2) determine feasibility of using protein content along with yield and soil data in identifying variable rate N application zones. In 2012, wheat, canola and peas were seeded. Soil samples and harvest measurements were taken from two transects in each field area. Wheat, canola and pea yields ranged from 882 to 2554, 1143 to 2342, and 839 to 3122 kg ha-1 respectively, while protein content for wheat, canola and peas ranged from 10.5 to 14.4, 14.2 to 20.6 and 14.5 to 17.7 percent respectively. Protein in wheat was positively correlated with pH in the 30-60 cm depth and negatively correlated with electrical conductivity in the 30-60 cm depth. Protein in canola was positively correlated with organic carbon in the 0-30 cm depth. Wheat yield was positively correlated with organic carbon in the 0-30 cm depth. Pea yield was negatively correlated with electrical conductivity in the 0-30 and 30-60 cm depths. In spring 2013, wheat was seeded on canola and pea stubble and canola seeded on wheat stubble with varied N rates on one side of each transect with a constant N rate on the other. Greater mean yields were observed from the varied N rate versus the control in the canola-wheat (3163 vs 2256 kg ha-1) and wheat-pea (4716 vs 4155 kg ha-1) rotations. A negative yield from the varied N rate versus the control was observed in the wheat-canola (2216 vs 3012 kg ha-1) rotation. However, these yield differences were not significant at p < 0.05.

The feasibility of using optical sensors and non-nitrogen limiting reference crops to determine post-emergent nitrogen fertilizer requirements of canola was evaluated. Normalized difference vegetation index was well suited for estimating yield potential and nitrogen status. Although sensor-based nitrogen management was generally agronomically feasible for canola, the economic benefits of doing so remain uncertain because of the added cost of applying post-emergent nitrogen.

Master of Science / Department of Agronomy / Antonio R. Asebedo / Johanna A. Dille / Field experiments were conducted in 2016 and 2017 across nine locations in Kansas to develop and evaluate a procedure for variable-rate applications (VRA) of soil-applied herbicides in corn and grain sorghum based on soil properties. Soil electrical conductivity (EC) and soil organic matter (SOM) data were collected at each location using a Veris MSP3. Soil EC was correlated to soil texture and herbicide algorithms were developed for two different tank-mixes for corn and for grain sorghum. Three algorithms were evaluated in the field for each tank-mix based only on SOM (alg-SOM), SOM and soil texture (alg-SOMtex), or a flat rate based on the average soil properties for the entire field. Rates for each tank-mix were based on the maximum usage rate (MUR) allowed. When soil variability across a field was adequate, VRA based on algorithms were effective at five of the nine locations. Across these five locations, alg-SOM resulted in the same or better weed control at 8 weeks after treatment (WAT) compared to the flat rate and reduced herbicide use by 12% for both tank-mixes in grain sorghum. Using alg-SOMtex reduced herbicide use by 24% in grain sorghum, but had less weed control at several locations compared to the flat rate. VRA was practical at Morganville, KS in 2017. Both alg-SOM and alg-SOMtex increased the amount of herbicide applied compared to the flat rate, but alg-SOMtex resulted in greater Palmer amaranth control (92%) compared to the flat rate (71%). Separate greenhouse and field experiments were conducted in 2017 to evaluate the activity of soil-applied herbicides on controlling HPPD-inhibitor resistant Palmer amaranth populations. A dose-response greenhouse experiment of soil-applied mesotrione and isoxaflutole was performed using resistant (Stafford County) and susceptible (Riley County) Palmer amaranth populations. Reduced susceptibility was observed with resistant-to-susceptible ratios being 7.2 for mesotrione and 4.1 for isoxaflutole. Field experiments were conducted at two locations in KS with one field having HPPD-resistant (Barton County) and the other HPPD-susceptible (Reno County) Palmer amaranth populations. Treatments were three HPPD-inhibiting herbicides [mesotrione (¼X, ½X, and 1X = 210 g ha-1), isoxaflutole (½X and 1X = 105 g ha-1), and bicyclopyrone (1X = 50 g ha-1 and 2X in formulated tank-mix with bromoxynil at 700 and 1400 g ha-1)] in comparison to other soil-applied herbicides commonly used for Palmer amaranth control. HPPD-inhibitor treatments were applied alone and tank-mixed with atrazine (2240 g ha-1). Overall, control of Palmer amaranth was reduced for HPPD-resistant compared to -susceptible populations. All treatments of mesotrione and isoxaflutole at 4 WAT resulted in 81 to 99% control in Reno County, but only 55 to 89% control in Barton County. For mesotrione and isoxaflutole treatments across both sites, Palmer amaranth control at 4 WAT was greater when 1X was applied (89%) compared to 0.5X (81%). Tank-mixing atrazine with mesotrione and isoxaflutole increased Palmer amaranth control from 82 to 88%. Soil-applied HPPD-inhibitors were most effective when applied at field usage rate in combination with atrazine for both populations. When using soil-applied HPPD-inhibitors, management recommendations should be the same regardless of Palmer amaranth population.

A operação de adubação responde por parte significativa dos custos de produção agrícola. Melhorar a qualidade dessa operação acarreta benefícios econômicos e ambientais. O processo de adubação normalmente é realizado a uma taxa média, representativa de uma área, no entanto, propriedades químicas do solo podem variar consideravelmente dentro dessa área. Desse modo, alguns locais poderão receber fertilizantes e/ou corretivos em excesso, enquanto outros poderão receber quantidades insuficientes. A alternativa à taxa média é a realizar a aplicação à taxa variada, que se caracteriza por aplicar os insumos de acordo com as necessidades específicas dentro da área. Para que essa aplicação aconteça, mecanismos dosadores controlam a aplicação. O objetivo deste estudo é avaliar os mecanismos dosadores de uma carreta adubadora de arrasto, comportas e esteiras, atendem as prescrições de doses previstas no mapa de recomendação de adubação. Para avaliar a uniformidade da operação utilizou-se o controle estatístico do processo. De acordo com os resultados obtidos pode-se afirmar que os mecanismos dosadores não atenderam a condição de realizar a aplicação à taxa variável de maneira uniforme. / The operation fertilization accounts for a significant portion of the costs of agricultural production. Improve the quality of this operation entails economic and environmental benefits. The process of fertilization is usually performed at an average rate representative of an area, however, the chemical properties of soil can vary considerably within the area. Thus, some locations may receive fertilizer and / or lime in excess, while others may receive insufficient amounts. The alternative is to average the application to perform variable rate, characterized by applying inputs according to the specific requirements within the area. For this application happens, metering mechanisms control the application. The aim of this study is to evaluate the dosing mechanisms of a truck hauling fertilizer, locks and mats, meet the requirements of the prescribed dose map fertilizer recommendation. To evaluate the uniformity of operation used the statistical process control. According to the obtained results it can be stated that the meter mechanism did not meet the condition to perform variable rate application to uniformly.

Plant canopy sensors have emerged as a new tool for in field on-the-go spatially localized prediction of plant biomass and nitrogen (N) uptake by crops in an indirectly and plant indestructible way as base for N variable rate fertilization. Sensors based on the combination of specific reflectance bands from the electromagnetic spectrum constitute the vast majority of canopy sensors, and this principle has already been validated in many crops. Alternatively to this concept, the use of ultrasonic distance sensors to measure crop canopy height has been presented as an option to estimate biomass. Based on that, the aim of this thesis was to validate and refine canopy sensor systems on automated diagnosis of plant parameters aimed the application of N fertilizer according sugarcane needs. Therefore, it was necessary to: 1) validate the prior calibration made for the reflectance sensor (Portz et al., 2012) and to establish the best time to use the sensor over the crop; 2) test the use of the reflectance sensor in comparative strips trials of uniform and sensor based N variable rate application testing algorithms with positive and negative slope and measuring productivity at the end of the season; 3) obtain the relationship between crop canopy height with accumulated biomass and N uptake by the crop during the initial growing season; 4) explore the plant height measured with an ultrasonic sensor comparing the results of biomass and N uptake prediction with those obtained with the reflectance sensor. The experiments were conducted on commercial sugarcane fields, and in strips of the crop with N variable rate application. The experiments were installed over clayey and sandy soils in dry and rainy seasons being all evaluated with the reflectance sensor Yara N-Sensor model ALS (N-Sensor&reg; ALS, Yara International ASA) and partly in comparison with an ultrasonic sensing system Polaroid 6500 (Polaroid, Minnetonka, MN, USA), when the crop had stalk height between 0.2 and 0.9 m. The reflectance sensor calibration fitted with the previous published data showing the interval between 0.3 - 0.5m as the most appropriate to use this sensor over sugarcane. The positive slope algorithm was superior to the negative, except in the situation of clayey soil in rainy season where the response from the negative slope algorithm was higher. The sugarcane plant height was highly correlated with biomass and N uptake by the crop, being possible to estimate the plants canopy height indirectly by the use of an ultrasonic sensor. Comparing the sensor systems, canopy reflectance was better in the early stages of crop as canopy height was more suitable for estimating the cultural parameters when the plants already covered soil in between the rows (+ 0.6 m stalk height), being the sensor systems complementary when fertilization is widely spread in the early crop growth period. / Sensores de dossel tem se apresentado como uma nova ferramenta para a predição espacialmente localizada, em tempo real, de forma indireta e indestrutiva da biomassa vegetal e extração de nitrogênio (N) pelas culturas como base para a aplicação de fertilizantes nitrogenados em taxas variáveis. Sensores baseados na combinação de faixas específicas de reflectância do espectro eletromagnético constituem a grande maioria dos sensores de dossel sendo este princípio já validado para uso em muitas culturas. Alternativamente a este conceito, a medição da altura do dossel cultural com o uso de sensor ultrassónico se apresenta como uma alternativa para a estimativa de biomassa vegetal. Com base nisso o objetivo desta tese foi de validar e aperfeiçoar sistemas sensores para a automação do diagnóstico visando à aplicação de fertilizante nitrogenado em função da necessidade da cana-de-açúcar. Para tanto, foi necessário: 1) validar a previa calibração feita ao sensor de reflectância (PORTZ et al., 2012) assim como estabelecer o melhor momento para uso do sensor na cultura; 2) ensaiar o uso do sensor em faixas comparativas entre taxa fixa e variável testando algoritmos de aplicação com inclinação positiva e negativa para dose de N mensurando produtividade; 3) obter a relação entre altura de dossel da cultura com, biomassa acumulada e extração de nitrogênio pela planta; 4) explorar a altura de plantas mensurada com um sensor ultrassónico comparando os resultados de predição de biomassa e extração de nitrogênio com aqueles obtidos com sensor de refletância. Os experimentos foram conduzidos em talhões comerciais de cana-de-açúcar e em forma de faixas da cultura, com aplicação em taxa variada de doses de N. Os experimentos foram instalados em solos de textura argilosa e arenosa nas épocas seca e chuvosa do ano sendo todos avaliados com o sensor Yara N-Sensor, modelo ALS (N-Sensor&reg; ALS, Yara International ASA), e em parte comparando com um sistema sensor ultrassónico Polaroid 6500 (Polaroid, Minnetonka, MN, EUA) quando a cultura apresentava altura de colmos entre 0,2 e 0,9 m. Os dados coletados para a calibração do sensor de reflectância se encaixaram exatamente aos dados já publicados mostrando-se o intervalo entre 0.3 e 0.5 m o mais indicado ao uso deste sensor. O algoritmo com inclinação positiva se mostrou superior ao negativo exceto na situação de solo argiloso em estação chuvosa onde a resposta do algoritmo negativo foi maior. A altura de planta de cana-de-açúcar se mostrou altamente correlacionável com biomassa e extração de nitrogênio pela cultura, sendo possível estimar a altura do dossel das plantas de forma indireta pelo uso do sensor ultrassónico. Comparando-se os sistemas sensores, reflectância de dossel se mostrou melhor em estádios iniciais da cultura enquanto altura de dossel se mostrou mais indicada para estimar os parâmetros culturais quando as plantas já recobriam as entrelinhas (+0.6 m colmo), mostrando-se os sistemas sensores complementares quando o período de fertilização for mais amplo na fase inicial da cultura.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Rice cultivation is on fundamental importance to the state s economy, where there is a need for improvements in productivity and profitability of farming located. This paper aimed to evaluate the production costs of the implementation of a rice farming using techniques of Precision Agriculture to obtain better productive incomes. The experiment was performed in the city of Rosário do Sul RS, in constant cultivation and with rotation of the rice, soy and grazing crops. The studied area is a section of 55 hectares and the methodology implemented was the comparative of two consecutive years of irrigated rice cultivation, being the crop in a conventional fertilization system in 2012/2013 and in 2013/2014 the cultivation was with the implementation of Precision Agriculture techniques. Necessary tools for the soil geo-referenced sampling were used to implement the Precision Agriculture techniques, and the recommendation and elaboration of input application maps. Through the obtained analysis, recommended corrections were made with the application of chalk, potassium and phosphorus in a variable rate, for goals of high crop efficiency. The result of the experiment determined a production cost for the implementation of precision agriculture techniques of 30,20% higher than the conventional crop cost. Respectively, it was also obtained an efficiency of 14,30% higher and profitability of 10,85% higher than the conventional crop. The reevaluation of the soil after the crop of 2013/2014 showed a significant improvement on the chemical attributes of the soil, justifying the high initial investment of the techniques implementation. Besides, the economic viability to purchase the centrifugal destributor was analyzed. This acquisition seemed to be economically viable for areas bigger than 200 hectares, if compared to the cost of service provider companies. / A cultura do arroz é de fundamental importância para a economia do Estado, onde há a necessidade de melhorias na produtividade e rentabilidade da lavoura implantada. Este trabalho teve como objetivo avaliar os custos de produção da implantação de uma lavoura orizícola utilizando técnicas de Agricultura de Precisão visando a obtenção de melhores rendimentos produtivos. O experimento foi realizado no município de Rosário do Sul RS, em área de cultivo contínuo com rotações das culturas de arroz, soja e pastagens. A área analisada foi um talhão de 55 hectares e a metodologia aplicada constituiu de um comparativo de dois anos consecutivos de cultivo de arroz irrigado, sendo na safra 2012/2013 o cultivo no sistema convencional de adubação e na safra 2013/2014 o cultivo com a implantação de técnicas de agricultura de precisão. Para a implantação das técnicas de AP utilizou-se as ferramentas necessárias para a amostragem georreferenciada do solo, a interpretação dos atributos químicos do solo, recomendação e elaboração dos mapas de aplicação de insumos. Através da análise obtida, fizeram-se as correções recomendadas com a aplicação de calcário, potássio e fósforo em taxa variável, para metas de alta produtividade da cultura. O resultado do experimento determinou um custo de produção para a implantação de técnicas de Agricultura de Precisão de 30,20% superior ao custo do cultivo de maneira convencional. Respectivamente, obteve-se também uma produtividade de 14,30% superior e lucratividade de 10,85% superior ao cultivo convencional. A reanálise do solo após a safra 2013/2014 mostrou uma melhora significativa nos atributos químicos, justificando o alto investimento inicial da implantação das técnicas. Além disso, foi analisada a viabilidade econômica da aquisição de distribuidor centrífugo, para a realização das aplicações de insumos em taxa variável. Esta aquisição se mostrou economicamente viável para áreas maiores de 200 ha, se comparados com o custo de empresas prestadoras de serviço.

The world population is projected to rise, and there is a growing concern of future food availability. Precision agriculture technologies are one solution to this problem as they aim to produce more food on less land. This study examines the adoption and intensity of precision agriculture technology usage by producers in North Dakota. Data from a North Dakota State University survey was collected and analyzed using an econometric double-hurdle model. Results of the study describe which producers adopt precision agriculture technologies, which technologies complement each other, and what affects the intensity of technology usage. Several technologies were found to have complementary effects on each other, larger farms are more likely to adopt PATs, and crop choices have varying impacts on the adoption and usage of PATs. Most of these findings agree with previous literature, although new light was shed on some new findings and predictions.