Fertilizer and lime investigations to determine their effect upon crops and soils have been carried out at many experiment stations. The correlation of the yield, the type and the chemical composition of vegetation and changes taking place in chemical properties of soil will contribute to a better understanding of soil fertility problems. Since 1940 the Virginia Agricultural Experiment Station, in cooperation with the Tennessee Valley Authority has conducted a pasture experiment on Coeburn Silt Loam in Wise County, Virginia. Several different fertilizer treatments with and without lime, were used to evaluate their effect upon pasture vegetation. The purpose of this study is to determine the extent of and nature of the effects of certain fertilizers and lime treatments on pasture vegetation and on the soil. The experiment was conducted on Coeburn Silt Loam, a soil derived from interbedded shale and arkosic sandstone. This soil is well drained, occurs on rolling to hilly relief, is low in inherent fertility and is fairly well adapted to agricultural uses. / Master of Science

An investigation of the amount of exchangeable potassium found in the surface and subsoils of a 33-year rotation experiment at Blacksburg, Virginia, was made. The rotation is located on Dunmore silt loam, Which is rated as a relatively fertile soil in Virginia. There are indications that sheet erosion has removed considerable amounts of the surface soil from the steeper slopes of the first nine treatments, and it is evident that an accumulation of this material has occurred on the four lower plots. It is believed by the writer, and others familiar with these plots, that.this erosion occurred prior to the beginning of the rotation in 1909. Composite soil samples were taken from each of the 8 treatments in each of the 4 series of this rotation and resulted in a total of thirty-two fertilized subplot samples, and a corresponding thirty-two unfertilized subplot samples were collected and analyzed for exchangeable potassium. Similar analyses were ma.de on the thirty-two subsoils of both the fertilized and the unfertilized treatments. The resulting data from the surface and subsoils were then statistically analyzed and the following conclusion drawn: 1. The applications of both muriate of potash and manure significantly increased the amount of exchangeable potassium found in both the surface and subsoils. 2. The surface soils are significantly higher in exchangeable potassium than the subsoils. 3. Exchangeable potassium may be leached from the surface horizon to the subsoil when applied in a complete fertilizer in excess of plant needs. 4. Manure applications which contained considerably less potassium than the potassium added to the soils in the muriate applications, resulted in larger amounts of exchangeable potassium in the surface soils, a 30 per cent increase in crop yields, and significantly less exchangeable potassium leached to the subsoils. 5. The difference in exchangeable potassium between the fertilized subplots receiving muriate of potash. and the unfertilized subplots. resulted in an increase in the amount of potassium found in the surface soils which was equivalent to 996 pounds of 50 per cent potash fertilizer, and this figure would represent an amount equivalent to 15 per cent of the total muriate added to the surface soils. 6. The difference in exchangeable potassium found in the subsoil between the fertilized and unfertilized plots represents an equivalent of approximately 9 per cent of the total potash added. 7. Significantly larger amounts of exchangeable potassium were leached to the subsoil from plots, receiving muriate of potash than soils which received manurial treatments. Greater utilization of the applied potassium is indicated by the manurial applications. 8. A chemical analysis should be made of the manure which is applied to this experiment in order to obtain a more comprehensive understanding of the yields, and physical and chemical properties of these soils. / M.S.

M.S.

Magistro darbe tiriama kadmio ir švino adsorbcijos ir desorbcijos procesai bei jų tarpusavio sąveika skirtingos granuliometrinės sudėties dirvožemiuose. Darbo objektas - du skirtingos granuliometrinės sudėties (priesmėlio ir priemolio) dirvožemiai. Darbo tikslas – ištirti kadmio ir švino adsorbcijos-desorbcijos procesus ir jų tarpusavio sąveikos poveikį jų judrumui tiriamuose dirvožemiuose. Darbo metodai – švino, kadmio, ir jų mišinių adsorbcijos dirvožemiuose procesui tirti dirvožemių ėminiai iki pusiausvyrosios būsenos buvo plakami su skirtingos koncentracijos (0, 0,25, 0,5, 1 mM) Cd (NO3)2, Pb(NO3)2 ir jų mišinių tirpalais, paruoštais 0,03M NaNO3 tirpale pastoviai joninei jėgai palaikyti. Po adsorbcijos eksperimento Cd2+ ir Pb2+ jonų koncentracijos pusiausvirajame tirpale nustatytos liepsnos atominės absorbcinės spektrometrijos metodu (AAS). Desorbcijos procesas ištirtas tuose pačiuose mėginiuose panaudojant ekstrakciją su 0,05M NH4 – EDTA (pH 7) ekstrahentu. Ekstraktuose Pb2+ ir Cd2+ jonų koncentracijos nustatytos liepsnos AAS metodu. Tyrimo rezultatai įvertinti matematiniais-statistiniais metodais naudojant Excel programą. Darbo rezultatai. Atlikus tyrimus nustatyta kad priesmėlio dirvožemis adsorbuoja (esant 1 mM (207 mg•kg-1) koncentracijai) 206,2 mg•kg-1 Pb, 109,9 mg•kg-1 Cd sausosios masės, o desorbuoja 97,7 mg•kg-1 Pb ir 61,6 mg•kg-1 Cd sausosios masės. O priemolio dirvožemis adsorbuoja esant tai pačiai koncentracijai 206,6 mg•kg-1 Pb ir 107,3 mg•kg-1 Cd s.m... [toliau žr. visą tekstą] / In this master work was investigated cadmium and lead adsorption – desorbtion processes and their interaction impact on thier imobility in soils of different texture. Work subject - two soils of different texture (loam and sandy loam). Work objective – to investigate cadmium and lead adsorption – desorbtion processes and their interaction impact on thier imobility in soils of different texture. Work methods – the investigated soil samples were agitated with Cd (NO3)2, Pb(NO3)2 solutions of different concentrations (0, 0,25, 0,5, 1 mM) as well as with solutions of thier mixtures. The solutions were prepared in the 0,03 M NaNO3 for the maintaining of constant ionic strength. After adsoption experiment, the Cd2+ and Pb2+ ionic concentrations in the equilibrium solution were determined with atomic adsorption spectrometer (AAS). The desorption was investigated in the same samples using 0,05M NH4 – EDTA (pH 7) extractant. In extracts Pb2+ and Cd2+ ionics concentrations were determinadet with AAS. Work results – after investigation observed that sandy soil absorbed 109,9 mg•kg-1 Cd and 206,2 mg•kg-1 Pb, desorbed 61,6 mg•kg-1 Cd and 97,7 mg•kg-1 Pb. And loam soil absorbed 107,3 mg•kg-1 Cd and 206,6 mg•kg-1 Pb, desorbed 57,1 mg•kg-1 Cd and 82,4 mg•kg-1 Pb. Cd in loam soil after Pb adsorption and desorption in Cd-Pb model-sistem the influence was tenuous, while the dorsorption decreased only in loam soil and only in the low concentations (unto 0,5 mM Cd-Pb). Keywords:... [to full text]

Ingeniero Civil Eléctrico / Este trabajo consiste en la generación de un set de datos con un respectivo ground truth (medición más confiable) y el uso de los algoritmos ORB-SLAM (Orientated FAST and Rotated BRIEF (Binary Robust Independent Elementary Features) Simultaneous Location And Mapping) y LOAM (Lidar Odometry And Mapping) a modo de entender de mejor forma el problema de SLAM (localización y mapeo simultaneo) y comparar los resultados obtenidos con el ground truth. A modo de entender de mejor forma el set de datos generado, la funcionalidad de los diferentes sensores es explicada. Los sensores utilizados para generar los datos son LIDAR, cámara estéreo y GPS. Este trabajo posee dos mayores etapas, en primer lugar, el GPS es estudiado para establecer las diferentes formas de extraer los datos desde el dispositivo. Una forma es generar un nodo de ROS que mediante comunicación de Bluetooth otorga un mensaje que puede ser leído. Otra forma es presionar tres veces el botón de encendido del GPS, lo que inicia el almacenamiento de los datos en la tarjeta SD. Mientras el primer método entrega mayor cantidad de información, es menos confiable, existiendo la posibilidad de guardar mensajes vacios o perdida de ciertos datos, afectando la tasa de muestreo. Finalmente una combinación de ambos métodos es implementada. Un set de datos de prueba es generado cerca de la Universidad De Chile, para probar que los datos están siendo almacenados correctamente. En el test se concluye que a modo de obtener mejor resultado con el GPS es necesario tomar los datos en zonas con baja cantidad de edificios. Finalmente con los datos y el ground truth el Error Absoluto de la Trayectoria (ATE) es calculado como método de comparación de ambas trayectorias generadas con los algoritmos mencionados. El ATE s la cantidad de energía necesaria para transformar la trayectoria estimada en el ground truth. Dadas ciertas limitaciones en la extracción de los datos estimados, la comparación se realizo entre dos set de datos de prueba, con pequeña cantidad de loops en el camino recorrido. En esta situación los resultados dados por LOAM son mejores que los obtenidos con ORB.SLAM. Pero en un ambiente con mayor cantidad de loops y una trayectoria más larga ORB-SLAM entregaría mejores resultados. ABSTRACT This work consists of the generation of a data-set with ground truth and the use of ORB-SLAM (Orientated FAST and Rotated BRIEF (Binary Robust Independent Elementary Features) Simultaneous Location And Mapping) and LOAM (Lidar Odometry And Mapping) algorithms as a way to better understand SLAM and to compare the ground truth and the data-set generated. To fully understand the data-set generated, the functionality of the different sensors is explained. The sensors used to generate the data-set are LIDAR, Stereo Camera and a GPS. This work is divided into two stages, in the first place the GPS is studied to establish the different ways to extract the data from it. One way is to generate a ROS node that through Bluetooth communication generates a message which is published. The other way is to press three times the button of the GPS to store the data in the GPS micro SD memory. While the first method is capable of store more data per second, it is less reliable, existing the possibility of store an empty message or simply the loss of data in the process. In the end, a combination of the two methods is implemented, modifying the bag file with the data stored in the micro SD. A test-data is generated near the University Of Chile, to prove that the bag file (a type of file that can contain any kind of information such as images, video or text, between others) is correctly generated. In these tests, it was concluded that to obtain better performance of the GPS therefore, obtain a better ground truth, it was necessary to generate the data in a zone with a low quantity of high buildings. Finally with the data-set and the ground truth the Absolute Trajectory Error (ATE) is used as a method to compare the trajectories. The ATE is the amount of energy that would require to transform the estimated trajectory on the ground truth. Since certain limitations of the extraction of the estimated path, the comparison was made between two small data-set which counted with low quantity of closed loops. Therefore the LOAM algorithm shows better results in this trajectory. The ORB-SLAM algorithm shows better results in data-sets with a high quantity of loops in the path.

In the past, most research on soil mechanical properties was carried out for cohesionless soils in the fields of civil and geotechnical engineering. Little research has been carried out for mechanical properties of agricultural soil, which are essential for designing soil engaging tools in agriculture. In this study, unconsolidated undrained triaxial compression tests were performed to study the effects of moisture level and confining pressure on a sandy loam soil. The soil specimens tested had three moisture levels, and they were high (27-29% d.b.), medium (19-21% d.b.) and low (9-11% d.b.). The confining pressures used for the triaxial tests were 50, 100, and 150 kPa. Soil specimen was loaded at a strain rate of 1%/min. Measurements from the tests included stress-strain curve, shear strength, Young’s modulus, Poisson’s ratio, angle of internal friction, and cohesion. A model was developed using the Discrete Element Method (DEM) and computed by Particle Flow Code in three dimensions (PFC3D), a common DEM software. The model simulated the triaxial compression tests, and the model specimen was an assembly of 5-mm spherical particles which were defined by a set of micro parameters. During simulations, soil shear strength was monitored under different confining pressures. Through sensitivity analysis, it was found that most of the micro parameters affected the simulated soil shear strengths and the stress-strain behaviours. The most influential micro parameter was particle friction coefficient. This micro parameter was calibrated with the data from triaxial tests for different combinations of soil moisture levels and confining pressures. The calibrated particle friction coefficients varied from 0.2 to 1.0. The calibrations were done through matching the shear strengths between simulations and measurements, and the relative errors ranged between 0 and 6 %. / October 2015

No description available.

Tiriamojo darbo objektas – ūkyje auginamų raudonųjų dobilų/daugiamečių svidrių, raudonųjų dobilų/pašarinių motiejukų, ir raudonųjų dobilų/tikrųjų eraičinų fitocenozės. Tyrimo tikslas – Atlikti raudonųjų dobilų/daugiamečių svidrių, raudonųjų dobilų/pašarinių motiejukų ir raudonųjų dobilų/tikrųjų eraičinų fitocenozių analizę priemolio išplautžemyje. Tyrimo metodika - Tyrimai vykdyti Plungės rajone. Tirti raudonųjų dobilų/daugiamečių svidrių, raudonųjų dobilų/pašarinių motiejukų ir raudonųjų dobilų/tikrųjų eraičinų žolynai. Botaninė žolyno sudėtis nustatoma svorio metodu, paimant mėginius iš kiekvieno lauko. Pavyzdžiai imami iš daugelio vietų. Analizuojant žolės suskirstomos į botanines grupes: varpines, ankštines ir įvairiažoles. Prie įvairiažolių dedamos piktžolės ir nesėtos tame lauke žolės. Jei yra kelios ankštinės žolės, tai jos išskiriamos ir pasveriamos atskirai. Žolės, suskirstytos į grupes, džiovinamos iki orasausės būklės ir pasveriamos. Po to apskaičiuojamas procentas sausųjų medžiagų derliuje. Žolyno derliui nustatyti pavyzdžiai buvo imami taip pat kaip ir botaninei sudėčiai sudaryti. Atliktos dvi pjūtys. Duomenys skaičiuoti pagal programą STAT-ENG Tarakanovas, Raudonius, 2003/. Tyrimo rezultatai. Trijuose skirtinguose žolynuose raudonųjų dobilų kiekis buvo skirtingas. Raudonieji dobilai, pasėti su daugiametėmis svidrėmis, žolyne sudarė 76,5 %. Daugiamečių svidrių buvo 20,6%. Raudonųjų dobilų/pašarinių motiejukų žolyne taip pat vyravo raudonieji dobilai. Jie... [toliau žr. visą tekstą] / Object of investigation – pulses/spica herbage, botanical composition and yield. Purpose of investigation is to analyze pulse/spica herbage in an ecological farm and provide measures to preserve pulses in herbage. Methods of investigation – Investigation has been carried out in Plungė District. Red clovers/perennial ryegrass, red clovers/feeding timothy grass and red clovers/fescue grass have been investigated. Botanical composition of herbage is estimated using the method of weight, when samples from each field are taken. Samples are taken from various places of a field. While analysing herbage is brought under botanical groups: spica, pulses and various other. Various other herbs consist of weeds and self-sown grass. If there are several kinds of pulses, they are separated and weighted separately. Drawn into several groups herbage are air-dried and weighted. Then the percentage of dry substances in yield is calculated. Herbage for the establishment of yield has been collected in the same way as for botanical composition. Two harvests have been fulfilled. Data have been calculated using programme STAT-ENG Tarakanovas, Raudonius, 2003/. Results of investigation. The amount of red clover in three fields has been different. Red clovers sown together with perennial ryegrass have made 76,5 % in herbage. Perennial ryegrass have amounted to 20,6%. Red clovers have prevailed in red clovers/feeding timothy grass herbage. They have made 57,1%. Feeding timothy grass has grown quite... [to full text]

Increasing levels of nitrate (NO3-) in groundwater have become a major environmental and health concern. In situations where NO3-concentrations in the soil-water system pose an environmental hazard, water table management may be a desirable practice to reduce such pollution. Careful management of N applications is also believed to reduce NO3- levels. / A field experiment was conducted in 1996 and 1997 at St. Emmanuel, Quebec, about 30 km South-West of Macdonald Campus of McGill University, to investigate the effect of water table management (WTM) and N fertilizer combinations on potentially leachable NO3- and denitrification rates in the top soil layer (0--0.15 m). The field was planted with monocrop corn (Zea mays. L) in both years. Treatments consisted of a factorial combination of two water table managements, free drainage (FD) and subirrigation (SI) (about 1.0 m and 0.6 m, respectively, below the soil surface) and two N fertilizer rates, 200 kg ha-1 (N200) and 120 kg ha-1 (N120). / Water table management had a significant effect on reducing NO3 - concentrations in the soil profile. Subirrigation treatment reduced NO3- in the top soil layer by 41% and 15% in 1996 and 1997, respectively. Similarly, NO3 - levels were 50% and 20% lower in N120 compared to N200 treatment. / Climatic conditions (rainfall and temperature) played a large role in regulating denitrification rates. Due to drier and cooler conditions in 1997, denitrification rates were lower compared to 1996, leaving more NO3 - in the soil profile. Following harvest, this high NO 3- concentration may be subject to leaching.

No description available.