Utilización de la cromatografía iónica en el análisis de muestras de aguas de drenaje y de solución de suelo

44 páginas, 7 figuras, 6 tablas.-- Memoria final presentada al XXIX Curso Internacional de Edafología y Biología Vegetal, patrocinado por UNESCO-AECI y CSIC que desde 1963 hasta 2009 se ha impartido en el Centro de Edafología y Biología Aplicada del Cuarto (CEBAC) y a partir de 1987 pasó a denominarse Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC).-- Existe un ejemplar de la publicación en la Biblioteca del Instituto de Recursos Naturales y Agrobiología de Sevilla-CSIC, para su consulta.Director del trabajo: Cabrera, FranciscoEl suelo es un recurso natural sumamente importante, su naturaleza está condicionada por multitud de factores, que van desde el sustrato geológico y la pendiente, hasta el clima y la comunidad biótica que soporta. A medida que se ha desarrollado el estudio del suelo, se ha visto que éste constituye una capa dinámica en la que constantemente tienen lugar numerosos y complejos procesos físicos, químicos y biológicos. Es esencial tener el mejor conocimiento de la naturaleza y propiedades de los suelos para darles el uso más eficiente para la producción de alimentos y fibras, y al mismo tiempo preservarlos para las generaciones venideras.El presente trabajo se ha realizado en el marco del CONTRATO STE-CT90-0032-C (DSCN) de la CE.Peer reviewe

Caracterización del endocarpio de Acrocomia aculeata como sustrato de cultivos

5 páginas.-- 3 figuras.-- 2 tablas.-- 12 referenciasSe ha estudiado el residuo de Acrocomia aculeata (coco paraguayo) para su uso potencial como sustrato y en enmiendas de suelos; se ha realizado la caracterización fisicoquímica de este residuo al natural y en forma pirolizada (Biochar) a tres temperaturas, 200º, 325º y 450ºC. El estudio se ha realizado con muestras molidas siendo el tamaño de partícula menor de 1 mm. El contenido de nitrógeno aumenta en los biochars respecto a la muestra cruda y entre los biochars aumenta al aumentar la temperatura, igual que ocurre con el P asimilable. Este aumento puede ser debido al incremento de compuestos heterociclos. Mediante el estudio de resonancia magnética nuclear en estado sólido se ha podido confirmar la presencia de lignina y celulosa en la muestra cruda. También se comprueba que después de una pirolisis a 200ºC o no hay cambios de composición o si los hay son tan sutiles que no se detectan. Los espectros de las muestras pirolizadas a 325 y 450ºC muestran cambios químicos significativos, las señales en los espectros indican degradación de la lignina y la celulosa. Con el análisis de las muestras mediante la técnica de microscopía electrónica de barrido se han observado diferencias significativas en la morfología y tamaño de poros de la muestra cruda respecto a las pirolizadas. Las isotermas de adsorción obtenidas muestran el aumento del área superficial en las muestras pirolizadas.Ministerio de Economía y Competitividad (España) CGL2015-64811-P y CITIUS- UNIVERSIDAD DE SEVILLAPeer reviewe

Efecto de dos tipos de biochar y de un compost de depuradora sobre la calidad de un suelo degradado

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Reducing fertilization for maize in Southwest Spain

A high nitrate pollution of groundwaters has been detected in recent years in many areas of southwest Spain where maize is cropped. This may be caused by the high fertilization level used in those areas. In this work, maize was grown consecutively for six years (1991-96) under Mediterranean management practices in the Guadalquivir River Valley (southwest Spain), using both a fertilization level widely used in the area (510 kg N ha-1 yr-1) and one third of it. The effect of the reduced fertilization on crop development, yield parameters and kernel analysis was studied. Nitrate leaching for each fertilization treatment was also monitored, during one experimental year. Crop development was slightly poorer in the plot with reduced fertilization, but no differences in yield were found. The only effect on kernel composition was a higher nitrogen (N) concentration in the kernels of the plot with the higher fertilization level. The amount of N supplied by the reduced fertilization, together with the N in the irrigation water and from the soil mineralization, was enough to counterbalance the N removed by the crop in years of high production. Nitrate leakage was three times greater in the plot with the higher fertilization level than in the plot with reduced fertilization. A marked reduction in crop performance was observed in both plots in the first three experimental years. Some stabilization was observed afterwards.This study was supported with funds of the European Community (contract STEP-CT90-0032) and the Junta de Andalucía (Research Group AGR151).Peer Reviewe

Losses of nitrate from a sandy loam soil under corn: lysimeter experiment

6 páginas, 5 figuras, 12 referencias.-- International Symposium on Irrigation of Horticultural Crops, celebrado del 23-27 de noviembre 1992, en Almería, España.Losses of nitrate from an undisturbed sandy loam soil contained in two monolith lysimeters, L0 and L1, (1 m diameter, 1.5 m deep) under corn and irrigation (628 mm) were studied. The crop was fertilized with 0 (L0) and 800 (L1) kg N ha-1. Water draining was collected periodically and analysed for nitrate content during the experimental period (20 March 91–23 March 92). Mean values of nitrate concentration in the drainage water were 3.1 and 41.2 mg NO3-N 1-1 in L0 and L1 respectively, the latter much higher than the limit imposed by the EC for potable water (11.3 mg N 1-1). Three periods were distinguished during the experiment: i) Crop season, in which the total volume of water drained was 310 and 47 mm respectively in the L0 and L1, while the nitrate losses were of the same order in both lysimeters (21 and 17 kg N ha-1, respectively); ii) Dry season, in which there was no water drainage; and iii) Rainy season, in which the total drained water was 157 and 139 mm, and the nitrate losses 5 and 91 kg N ha-1 in L0 and L1 respectively. The greater amount of water drained in L0 is due to the lower crop development (grain yield 4.4 and 21.3 t ha-1; total nitrogen plant uptake 69 and 400 kg N ha-1, in L0 and L1 respectively). Total nitrate losses in L1 account for 13% of the nitrogen fertilizer applied. Most of these losses occur in the rainy season. At the end of the experimental period a decrease of the soil nitrate content was observed in both lysimeters.Research carried out in the framework of contract No. STEP-CT90-0032-C (DSCN) of the CE.Peer Reviewe

Nitrate leaching under irrigated agriculture

9 pages, 2 figures, 29 references.-- Proceedings of the NATO Advanced Research Workshop on Sustainability of Irrigated Agriculture Vimeiro, Portugal March 21-26, 1994.-- Publicado en el capítulo V: Water Quality Management.In lhe last two or three decades nitrogen (N) fertilizers have been applied to agricultural soils at high rates to obtain higher crop yields. The increase in the nitrate concentration in both groundwaler and surface water is related to agricultural practices. The use of nitrogen fertilizers at rates higher than the rate of uplake by the plant increases the potential for increased nitrate leaching, as has been shown by Roth and Fox (1990) for nitrogen-fertilized corn.The research was carried out in the framework of contract No. STEP CT90-0032-C of the CE.Peer reviewe

Estimating the flux of nitrate in a sandy loam soil under corn

5 páginas, 3 figuras, 1 tabla, 14 referencias.-- Proceedings of the International Symposium "Fertilizers and Environment", held in Salamanca, Spain, 26-29, september, 1994.Drainage and nitrate leaching were determined in an undisturbed sandy loam soil contained in two monolith lysimeters (Ll and L2; 1.2 m deep) cropped with corn, irrigated, and fertilized with 510 and 175 kg N ha-1 in L1 and L2 respectively. Drainage was estimated at 0.9 m depth using Darcy's law and the hydraulic conductivity-soil water content relationship. Nitrate leaching at the same depth was obtained multiplying the estimated drainage by the nitrate concentration of the soil solution extracted with suction cups. A comparison between results from measurements at the bottom of lysimeters and that estimated at 0.9 m depth was made for the whole experimental period (March 1992-February 1993). The N03-N concentrations in the drainage water ranged between 2.8 and 151 mg 1-1 in L1 and between 0.1 and 34.4 mg 1-1 in L2. In the soil solution, they ranged between 5.9 and 240.3 mg NO3-N 1-1 in Ll and between 0.1 and 42.3 mg NO3-N 1-1 in L2. The total drainage at the bottom of lysimeters amounted to 139 and 203 mm and that estimated at 0.9 m depth amounted to 151 and 245 mm, in L1 and L2 respectively. Total NO3-N leached in L1 and L2 was 80 and 30 kg ha-1 respectively. The estimated amounts of NO3-N leached below 0.9 depth were 64 and 42 Kg ha-1 in L1 and L2 respectively. Total drainage and nitrate leached measured at the bottom were of the same order as the estimated values.Research carried out in the framework of the contract No. STEP-CT90-0032 of the C.E.Peer reviewe

Water balance and nitrate leaching in an irrigated maize crop in SW Spain

14 páginas, 6 figuras, 4 tablas, 9 referencias.-- Constituye el Capítulo 7.-- Report of an FAO/IAEA Co-ordinated Research Program by Using Nuclear Techniques.-- Executed by the Soil and Water Management&Crop Nutrition Section of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture.During 3 consecutive years (1991-1993) a field experiment was conducted in an intensively irrigated agricultural soil in SW Spain. The main objective of this study was to determine the water flow and nitrate (NO3) leaching, below the root zone, under an irrigated maize crop and after the growing season (bare soil and rainy period). The experiment was carried out on a furrow-irrigated maize crop at two different nitrogen (N)-fertilization rates, one the highest traditionally used by farmers in the region (about 500 kg N ha-1 per year) and the other one-third of the former (170 kg N ha-1 per year). The aim was to obtain data that could be used to propose modifications in N-fertilization to maintain crop yield and to prevent the degradation of the environment. The terms for water balance (crop evapotranspiration, drainage and soil water storage) and nitrate leaching were determined by intensive field monitoring of the soil water content, soil water potential and extraction of the soil solution by a combination of neutron probe, tensiometers and ceramic suction cups. Nitrogen uptake by the plant and NO3-N produced by mineralization were also determined. The results showed that, in terms of water balance, crop evapotranspiration was similar at both N-fertilization rates used. During the irrigation period, drainage below the root zone was limited. Only in 1992 did the occurrence of rainfall during the early growing period, when the soil was wet from previous irrigation, cause considerable drainage. Nitrate leaching during the whole experimental period amounted to 150 and 43 kg ha-1 in the treatments with high and low N-fertilization, respectively. This occurred mainly during the bare soil and rainy periods, except in 1992 when considerable nitrate leaching was observed during the crop season due to the high drainage. Nitrate leaching was not so high during the bare soil period as might have been expected because of the drought during the experimental period. A reduction of N-fertilization thus strongly decreased nitrate leaching without decreasing yield.Research was carried out in the framework of the contract STEP-CT90-0032 of the European Community.Peer reviewe

Leaching of nitrate from a sandy loam soil under corn and two N-fertilizations

Nitrate losses in two undisturbed soil1ysirneters cultivated with corn under irrigation and fertilization (higher in Ll than in L2) were studied. Total drained water volume during the experimental period was higher in L2 than in Ll. Differences can be attributed both to different patterns of soil water dynamics and crop development in each lysimeter. Nitrate losses were higher in Ll than in L2 and occurred mainly during the crop season. This abnormal nitrate losses distribution seems to be due to the scarcity and uneven distribution of rainfall during autumn 1992.Peer Reviewe

Effect of irrigation with saline water on soil and crop in South-West Spain

8 páginas, 5 figuras, 2 tablas, 5 referencias.-- Portuguese National Committee of the International Commission on Irrigation&Drainage.-- Select papers of the 1st Inter-Regional Conference "Environment-Water: Innovative Issues in Irrigation and Drainage", feld in Lisbon, Portugal, September 1998.The drained and irrigated marshes of the Guadalquivir river (SW Spain) are formed on soils of high elay content (about 70%), high salinity, and a shallow, extremely saline, water table. Irrigation is necessary for successful crop production in this region of low and variable rainfall. In some years, however, water supply for irrigation is limited due to drought periods, and farmers are obliged to irrigate with river water, which at this location is of high salinity due to tidal flow. The objective of this work was to evaluate the effects of irrigation with water of high salinity on soil properties and growth and yield of cotton crop. The experiments were carried out during 1997. Irrigation was applied by furrows. Water content profile, tensiometric profile, water table level, drainage water flow, soil salinity, leaf water potential, stomatal conductance, and crop development and crop yield were monitored. The results showed that after the irrigation with saline water, the soil salinity increased. This increase was more noticeable in the top layer (0-30 cm depth). After five irrigations with water of good quality, the salinity of the soil in the subplot irrigated with saline water reached values similar to those before the application of saline water. The irrigation with saline water affected crop development. Despite the negative effects on crop development and water status in plants, the crop yield was the same as on the subplot irrigated with nonsaline water.This study was supported with funds ofthe Spanish CICYT, projeet HID96- 1292, and the Junta de Andalucía (Research Group AGR-151).Peer reviewe