Nitrogen fertilization in agriculture has serious environmental consequences, including production of the greenhouse gas nitrous oxide (N₂O), pollution of groundwater with nitrate (NO₃^-), and river eutrophication. Nitrogen use efficiency can be increased by amending fertilizers with inhibitors to slow microbial nitrification processes, which transform ammonia to NO₃^-. Unfortunately, commercial inhibitors have failed to perform reliably across various agroecosystems for reasons not well understood. Using a combination of bacterial studies and soil incubations, we demonstrate here that 4-methyl-1-(prop-2-yn-1-yl)-1H-1,2,3-triazole (MPT) exhibits superior nitrification inhibitory properties. Unlike the commercial reversible inhibitors, MPT acts as a mechanistic, irreversible inhibitor of the key enzyme ammonia monooxygenase, enabling effective retention of ammonium (NH₄⁺) and suppression of NO₃^- and N₂O production over 21 days in several agricultural soils with pH values ranging from 4.7 to 7.5. A bacterial viability stain and a suite of freshwater and terrestrial ecotoxicity tests did not indicate any acute or chronic toxicity. Real-time quantitative polymerase chain reaction (qPCR) analysis revealed an enhanced inhibitory effect of MPT on both ammonia-oxidizing bacteria and archaea. Thus, MPT outperforms currently available nitrification inhibitors and has great potential for broad application in various agricultural settings.

More people to feed, reduced arable area, and more extreme environ mental conditions creates constraints never seen before in agricultural systems. In order to feed the increasing world population, plant yield improvement needs to be achieved. Photosynthesis, a process that is tightly related to plant yield, is limited by the efficiency of Rubisco. This enzyme, responsible for the carbon fixation that ulti mately leads to the production of photoassimilates, is limited by its dual role, working as a carboxylase and an oxygenase. When it works as an oxygenase, it produces 2-phosphoglycolate, which needs to be recycled through a process called photorespiration, leading to CO2 and energy losses. To overcome photorespiration, some plants have evolved carbon concentrating mechanisms that allow the increase of CO2 concentration around Rubisco, thus reducing its oxygenase activity. One such mechanisms is C4 photosynthesis. In most C4 plants, two carboxylation reactions take place in two different cell types, mesophyll and bundle sheath. | N/A

In dynamical system theory, the process of obtaining a reduced-order approximation of the high-order model is called model order reduction. The closeness of the reduced-order model to the original model is generally gauged by using system norms of additive or relative error systems. The relative error is a superior criterion to the additive error in assessing accuracy in many applications like reduced-order controller and filter designs. In this paper, we propose an oblique projection algorithm that reduces the norm of the relative error transfer function. The selection of reduction matrices in the algorithm is motivated by the necessary conditions for local optima of the (squared) norm of the relative error transfer function. Numerical simulation confirms that the proposed algorithm compares well in accuracy with balanced stochastic truncation while avoiding the solution of large-scale Riccati and Lyapunov equations.

Seminatural European grasslands and pastures have a high conservation value because they provide different goods and services (meat, wool, carbon sequestration, etc.) and harbor diverse communities of plants and animals. These land use systems were created by low- and moderate-intensity use and, nowadays, face threats from both abandonment and overuse. Although less productive or less accessible areas are abandoned, triggering afforestation processes, others are subject to intensive agricultural practices with the addition of production factors and modern management schemes. Neither is comparable with the traditional uses that first formed and maintained these systems for generations, and therefore, it is fundamental to design effective policies to ensure a sustainable territorial coexistence of modern agriculture and traditional pastures and grasslands. In this work, we assessed the recent dynamics of pastures and grasslands in Slovenia. The results show distinct local changes and a nationwide general dynamic of area reduction and loss of patches. After elaborating on how such changes affect the landscape and some species according to their traits, we provide practical recommendations for policy design to contribute to protecting and promoting this land use system. We argue that the two major priorities should be to preserve the most relevant patches and to try to convert other land uses into grasslands, preferably attempting to merge separated patches and thus increasing the mean patch size of grasslands. Overall, by identifying trends, locating the different spatial changes, and complementing with a connectivity analysis, this approach can be valuable in identifying effective measures to protect and improve grasslands. Besides the concrete results obtained from the Slovenian case study, the underlying rationale and workflow can be applied elsewhere to produce similar outputs that help identify land transformation patterns and interpret specific land use category dynamics.

Gráficas, tablas, fotografías | spa:El Departamento de Boyacá, posee un buen potencial para contribuir a la producción de alimentos y la seguridad alimentaria, a través de los modelos de ganadería lechera especializada y tradicional establecidos en diferentes regiones. Sin embargo, la falta información sobre la calidad fisicoquímica e higiénica de la leche, la heterogeneidad en los sistemas de producción lechero y la influencia de factores climáticos en la zona centro del departamento, sugiere que se plantee como objetivo principal de la investigación, la caracterización de las prácticas ganaderas en los sistemas de producción bovino y análisis de calidad de leche en la zona centro del departamento. Materiales y métodos: Se desarrolló una investigación descriptiva de corte longitudinal, con enfoque cuantitativo de los sistemas de producción lechera y se dividió en 4 fases:1. Análisis del comportamiento de las variables meteorológicas y su efecto en los sistemas de producción lechero; se estudiaron 4037 datos sobre las variables humedad, temperatura y precipitación, reportadas por el Instituto de Estudios Ambientales y Meteorológicos y se relacionó su efecto en los modelos productivos ganaderos de municipio. Fueron georreferenciados 271 hatos lecheros y recopiladas estadísticas de producción, con el fin de analizar los factores climáticos que podrían interferir con la producción de leche. 2. Diagnóstico y caracterización de la producción lechero a través del análisis de 7560 variables fisicoquímicas grasa, proteína, sólidos totales, sólidos no grasos, lactosa, densidad, agua adicionada, sales, pH y el análisis del recuento de células somáticas de la leche, a través ultrasonografía y Citometría de Flujo. 3. Evaluación de la concentración de caseína a través de espectrofotometría ultravioleta visible y rendimiento quesero de la leche de vaca producida en la zona de estudio. Para el análisis estadístico se utilizó el método de análisis multivariado, los datos cuantitativos y cualitativos se sometieron a un análisis de parámetros estadísticos descriptivos y análisis de varianza, se aplicó la prueba Tukey y Levene, el proocesamiento estadístico se realizó utilizando el programa SPSS versión 19.0. Resultados: se evidenció que en los últimos cuatro años las variables temperatura, precipitación y humedad relativa han tenido marcadas variaciones. La temperatura máxima incremento 1.3°C, pero a la vez se ha alcanzado los mayores picos de temperatura mínima (< -4°C), acompañados de periodos de sequía y lluvia intensos y cambios en la humedad relativa; condiciones que afectan de manera sensible al sector agropecuario y ponen en riesgo la seguridad alimentaria de la población. Se hallaron en las unidades de producción (UP) pastos tradicionales (Pennisetum clandestinum y Lolium perenne) y alimentación bovina complementaria durante las estaciones secas; las razas que predominan son, Normando. Holstein, Jersey y cruces, el ordeño se realiza en la mañana y de forma manual (76.3%). En relación a la calidad fisicoquímica de la leche los promedios las variables evaluadas obtenidas indican una buena calidad composicional (3.89% Grasa, 3.38% Proteína, 12.41% Sólidos Totales, 8.52% Sólidos no grasos y 4.48% Lactosa,); el 47.1% de los resultados de los recuentos de células somáticas (RCS) demostraron que la leche es considerada de buena a excelente calidad, con recuentos <200.000 cel/mL y el 12.85% se ubicó en un rango de >201.000 a 4.00.000 (células/mL). La concentración de caseína correspondió al 2.4% de las proteínas totales y el rendimiento promedio de queso elaborado de leche fresca fue de 8.4 lts/kg. Conclusiones. Los resultados obtenidos, muestran que el cambio climático es el desafío ambiental más importante de la humanidad, siendo una amenaza para el bienestar de la población mundial. Además, se evidenció que más del 60% de las muestras analizadas, cumplen con lo establecido por el Decreto 616 del 2006, para ser procesada con el fin de obtener buenos rendimientos de queso en la zona de estudio, igualmente se observó el interés en el desarrollo ganadero a través del procesamiento de la leche, como parte fundamental para la generación de ingresos a nivel familiar y desarrollo económico de la región. | eng:The Department of Boyacá has a good potential to contribute to food production and food security through specialized and traditional dairy farming models established in different regions. However, the lack of information on the physicochemical and hygienic quality of the milk, the heterogeneity in the milk production systems and the influence of climatic factors in the central zone of the department, suggests that the main objective of the investigation be the characterization of livestock practices in bovine production systems and analysis of milk quality in the central area of the department. Materials and methods: A longitudinal descriptive investigation with a quantitative approach to dairy production systems was developed and divided into 4 phases: 1. Analysis of the behavior of meteorological variables and their effect on dairy production systems. 4037 data on the variables humidity, temperature and precipitation, reported by the Institute of Environmental and Meteorological Studies, were studied; and its effect on the livestock production models of the municipality was explained. 271 dairy herds were georeferenced and production statistics were compiled, in order to analyze climatic factors that could interfere with milk production. 2. Diagnosis and characterization of dairy production through the analysis of 7,560 physicochemical variables: fat, protein, total solids, non-fat solids, lactose, density, added water, salts, pH, and analysis of somatic cell count in milk, through ultrasonography and Flow Cytometry. 3. Evaluation of casein concentration through visible ultraviolet spectrophotometry and cheese yield of cow's milk produced in the study area. For the statistical analysis, the multivariate analysis method was used, the quantitative and qualitative data were subjected to an analysis of descriptive statistical parameters and analysis of variance. The Tukey and Levene test was applied and the statistical processing was carried out using the SPSS version 19.0 program. Results: It was evidenced that in the last four years the variables temperature, precipitation and relative humidity have had marked variations. The maximum temperature increased by 1.3°C, but at the same time the highest minimum temperature peaks (< -4°C) have been reached, accompanied by periods of intense drought and rain and changes in relative humidity. These conditions significantly affect the agricultural sector and put the food security of the population at risk. Traditional pastures (Pennisetum clandestinum and Lolium perenne) and complementary bovine feeding during the dry seasons were found in the production units (PU). The predominant breeds are Norman, Holstein, Jersey and interbreeds. Milking is done in the morning and manually (76.3%). In relation to the physicochemical quality of the milk, the averages of the evaluated variables obtained indicate a good compositional quality (3.89% Fat, 3.38% Protein, 12.41% Total Solids, 8.52% Non-fat Solids and 4.48% Lactose). 47.1% of the results of the somatic cell counts (SCC) showed that the milk is considered to be of good to excellent quality, with counts <200,000 cells/mL. 12.85% were located in a range of >201,000 to 4,00,000 (cells/mL). The casein concentration corresponded to 2.4% of the total proteins and the average yield of cheese made from fresh milk was 8.4 liters/kg. Conclusions. The results obtained show that climate change is the most important environmental challenge for humanity, since it is configured as a threat to the well-being of the world population. In addition, it was evidenced that more than 60% of the analyzed samples comply with the provisions of Decree 616 of 2006, to be processed in order to obtain good cheese yields in the study area. Likewise, the interest in livestock development was observed as a fundamental part for the generation of income at the family level and economic development of the region through the processing of milk. | Page LIST OF FIGURE/IV LIST OF TABLE/V LIST OF APPENDICES/VI ABSTRACT /1 CHAPTER I. /1. INTRODUCTION / CHAPTER II. / 2. LITERATURE REVIEW / 2.1 Current Context of the Dairy Sector. / 2.2 Compositional characteristics of cow's milk. / 2.3 Hygienic And Microbiological Quality Of Bovine Milk/2.4 Legislation Governing The Dairy Sector/ CHAPTER III/3. EFFECT OF THE CLIMATIC CONDITIONS TEMPERATURE, RAINFALL AND RELATIVE HUMIDITY IN CATTLE RAISING PRODUCTION SYSTEMS IN THE MUNICIPALITY OF TOCA-BOYACÁ / CHAPTER IV. / 4. CHARACTERIZATION OF BOVINE PRODUCTION SYSTEMS AND MILK QUALITY USED FOR THE PRODUCTION OF CHEESE CHAPTER V. / 5. EVALUATION OF COMPOSITIONAL PARAMETERS AND CASEIN CONCENTRATION IN MILK COLLECTED FOR THE ELABORATION OF DOUBLE CREAM CHEESE AND MOZZARELLA TYPE IN TOCA. BOYACÁ. CHAPTER VI. / 6. RESEARCH IMPACT | Doctorado | Doctor(a) en Ciencias Agrarias