Scielo RSS <![CDATA[Revista de la ciencia del suelo y nutrición vegetal]]> http://www.scielo.cl/rss.php?pid=0718-279120090003&lang=es vol. 9 num. 3 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.cl/img/en/fbpelogp.gif http://www.scielo.cl <![CDATA[PELLETIZATION OF <i>Anthracophyllum discolor </i>FOR WATER AND SOIL TREATMENT CONTAMINATED WITH ORGANIC POLLUTANTS]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-27912009000300001&lng=es&nrm=iso&tlng=es Pellets of the white-rot fungus Anthracophyllum discolor with activated carbon and sawdust (complex pellets) were formulated for the degradation of lignin in water and the bioremediation of soil contaminated with pentachlorophenol (PCP). The complex pellets were formed by a center of activated carbon and sawdust surrounded by fungal mycelium, whereas simple pellets consisting of only mycelium were hollow spheres. Degradation of lignin was performed in an airlift reactor at initial lignin concentration of 1000 mg L-1 and the fungal pellets were re-used two times in batch operations. Complex pellets degraded lignin by 87 and 72% in the first and second cycle, respectively, and they were significantly more effective than simple pellets. In addition, complex pellet showed higher manganese peroxidase activity in the reactor. For the bioremediation of soil contaminated with PCP (150 mg kg-1 of soil) the pellets were added to soil surface. PCP degradation in soil with complex pellets was 85% at 28 days of bioaugmentation, being higher than in soil with simple pellet. A fungus growth was also observed only in soil with complex pellet. Sawdust and activated carbon appear to be suitable carriers of A. discolor for degradation of organic pollutants in wastewater and soil. <![CDATA[<strong>VARIABILIDAD ASOCIADA A LA DETERMINACIÓN DE RESIDUOS DE CLORPIRIFOS AL SER APLICADO EN UN HUERTO DE MANZANOS</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-27912009000300002&lng=es&nrm=iso&tlng=es The present study had the purpose of testing through supervised trials the variability of Chlorpyrifos (CHP) residues associated to a sampling methodology validated in the field, on applying the active ingredient (AI) in an apple orchard, with two different spraying methodologies and at different periods of vegetative development. The persistence on applying 1.8 kg ha-1 (Lorsban 50%WP®, Dow AgroScience, USA), using a knapsack sprayer with engine (KSE) and a high volume sprayer (HVS) was studied. The model that had the best fit for the diminution of the residues was appraised through linear regression. The results show high coefficients of variation (CV) with both application methods, KSE (69%) and HVS (43%). The sampling variability of apples contributes to 99.3% with KSE and 97.7% with HVS. The sample results show an initial rapid diminution of CHP, with a half-life for apples, leaves and soil of 5.0, 2.3 and 4.5 days for KSE and 8.3, 2.7 and 11.2 days for HVS, respectively. The adjusted declination model for each substrate does not permit modeling the degradation of CHP residues through a simple model.<hr/>El presente estudio tiene por objetivo probar mediante ensayos supervisados la variabilidad de los residuos de clorpirifos (CHP) asociados a una metodología de muestreo validada en terreno, al aplicar el ingrediente activo (IA) en huerto de manzanos, con dos diferentes metodologías de aspersión y en épocas diferentes de desarrollo vegetativo. Se estudió la persistencia al aplicar 1,8 kg ha -1(Lorsban 50%WP®, Dow AgroScience, USA), mediante nebulizadora con bomba de espalda con motor (NBEM) y con nebulizadora de alto volumen (NAV). Se evaluó el modelo que representa el mejor ajuste de la declinación de los residuos a través de regresión no lineal. Los resultados muestran altos coeficientes de variación (CV) en ambos métodos de aplicación, NBEM (69%) y NAV (43%). La variabilidad del muestreo de manzanas contribuye con un 99.3% con NBEM y 97.7% con NAV. Los resultados muestran una disminución inicial rápida del CHP, con una vida media para manzanas, hojas y suelo de 5,0; 2,3 y 4,5 días para NBEM y de 8,3; 2,7 y 11,2 días para NAV, respectivamente. El modelo de declinación ajustado para cada sustrato no permite modelar la degradación de los residuos de CHP a través de un modelo simple. <![CDATA[<b>EFECTO DEL CAMBIO DE USO EN LA ESTABILIDAD DE LA ESTRUCTURA Y LA FUNCIÓN DE LOS POROS DE UN ANDISOL (TYPIC HAPLUDAND) DEL SUR DE CHILE</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-27912009000300003&lng=es&nrm=iso&tlng=es Volcanic soils in southern Chile cover approximately 60% of the arable land in the country. These soils are under a wide range of land uses from pristine systems to intensively used ones. The objective of this study was to determine the effect of the land use change on: i) the structural stability after external and internal forces, ii) the hydraulic conductivity and iii) its functional resilience. Disturbed and undisturbed soil samples were collected at 5, 20 and 40 cm depths in an Andisol (Typic Hapludand) under native forest (NF), 50 year old pasture (P50) and 1 year old pasture (PI). The water retention, shrinkage and consolidation curves, hydraulic conductivity (Ks), air permeability (Ka), organic carbon content (CO), soil texture and allophane contents were determined. The unsaturated hydraulic conductivity (Ku) was estimated according to van Genuchten (1980). Soil deformation indexes as a consequence of mechanical (COLEm) and hydraulic (COLEh) stresses were calculated. The studied soil is subject to continuous changes in their structure as a consequence of mechanical and hydraulic stresses affecting the pore size distribution and its functionality. The magnitude of these changes decreased with the increasing intensity of the land use. The great shrinkage capacity of the soil may have consequences on its hydraulic behaviour depending on the drying intensity through the formation of cracks and preferential path flows. Finally, the soil pores are able to recover its functional integrity after compaction, which is strongly related to the presence of organic matter contents.<hr/>Los suelos volcánicos del sur de Chile constituyen cerca del 60% del suelo arable del país. Estos suelos se encuentran bajo un amplio rango de usos desde sistemas prístinos hasta otros con un uso intensivo. El objetivo de este trabajo fue determinar el efecto del cambio de uso de suelo sobre: i) la estabilidad del suelo frente a presiones externas e internas; ii) la conductividad hidráulica y iii) su resiliencia funcional. Muestras disturbadas y no disturbadas de suelo fueron recolectadas a 5, 20, 40 cm de profundidad en un suelo Andisol (Typic Hapludand) bajo un renoval de bosque nativo (NF), una pradera de 50 años (P50) y otra de 1 año de uso (Pl). Se determinó la curva de retención de agua, contracción y consolidación, la conductividad hidráulica saturada (Ks), permeabilidad de aire (Ka), contenidos de carbono orgánico (CO), textura y alofán. Se estimó la conductividad hidráulica no saturada (Ku) de acuerdo al modelo propuesto por van Genuchten (1980). Se definieron índices de deformación de suelo como consecuencia de estreses mecánicos (COELm) e hidráulicos (COELh). El suelo estudiado está sujeto a constantes cambios en su estructura como consecuencia de estreses mecánicos e hidráulicos afectando la distribución de los poros y su funcionalidad. La magnitud de estos cambios disminuye con el incremento de la intensidad de uso del suelo. La gran capacidad de contracción del suelo puede traer consecuencias en su comportamiento hidráulico dependiendo de la intensidad del secado a través de la formación de grietas y vías de flujo de preferencial. Finalmente, los poros del suelo son capaces de recuperar su integridad funcional después de una compactación, lo que está estrechamente relacionado con los contenidos de materia orgánica. <![CDATA[<b>C</b><b>ONDUCTIVIDAD HIDRÁULICA EN MONOLITOS DE SUELO DE CHILE CENTRAL</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-27912009000300004&lng=es&nrm=iso&tlng=es Four monoliths with contrasting textural classes (Sc, Scl, Ssl and Sls) from soils (Fluventic Haploxerolls and Typic Xerochrepts) of central Chile were used to obtain soil hydraulic conductivity at different slope gradients (0%, 15%, 20% and 25%) with tension infiltrometer, under laboratory conditions. A total of 13 supply pressure heads (Ψs between -140 and -20 mm) were used to obtain the unsaturated hydraulic conductivity (KΨ). Paired data [In(KΨ) y Ψs] were adjusted by two-linear models that assumed a continuous exponential function in a macroporous and mesoporous system, which considered a boundary supply pressure head. Extrapolating to zero supply pressure head, field saturated hydraulic conductivity (K∫s) was estimated. In all soils, when a gravitational adjustment to supply pressure heads was used, K∫s values were strongly negatively correlated to slope gradient. It is attributed to a refraction of water flow, which considered the greater frictional or viscous resistance generated by inclination.<hr/>Se evaluó, con tensioinfiltrómetro y en condiciones de laboratorio, la conductividad hidráulica de suelos en distintos gradientes de pendiente (0%, 15%, 20% y 25 %) utilizando cuatro monolitos de clases texturales contrastantes (S A, S FA, S Fa y SaF), provenientes de suelos (Fluventic Haploxerolls y Typic Xerochrepts) de la zona central de Chile. Se emplearon 13 potenciales de suministro de agua (Ψs) entre -140 y -20 mm. Obtenida la conductividad hidráulica insaturada (KΨ) para cada Ψs , los valores pareados [ln(KΨ) y Ψs] fueron ajustados a un modelo bilineal, asumiendo que una función exponencial continua de KΨ es aplicable al sistema macroporoso y mesoporoso, con un quiebre a un potencial límite. La conductividad hidráulica saturada (K∫s) se estimó extrapolando al potencial de suministro cero. Así, al realizar un ajuste gravitacional del potencial de suministro, K∫s mostró una marcada tendencia a disminuir en todos los suelos al aumentar el gradiente de pendiente, lo que se atribuye a una refracción del flujo de agua, considerando la mayor resistencia friccional o viscosa que se genera al inclinar el suelo. <![CDATA[<strong>CARBONO ORGÁNICO DEL SUELO EN DIFERENTES USOS DEL TERRENO DE PAISAJES ANDINOS COLOMBIANOS</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-27912009000300005&lng=es&nrm=iso&tlng=es The relationship between changes in land use and soil carbon and nitrogen was assessed in Alcalá (Colombian coffee growing region), between 900 and 1600 m. Soils are Argiudolls and Melanudands and sampling units were defined according to the altitudinal gradient. Carbon and nitrogen content, C:N ratio, bulk density and 13C and 15N abundances were measured. Significant differences (p < 0.05) were found due to altitude effect, differentiating the high zone by high C (37.06 -42.88 t ha-1), N (3.12-3.86 t ha-1) and C: N (11.17-11.97), low bulk density (0.56-0.65 g cm-3) and 15N abundance (4.59-5.15 %o). Fallow and monocultures stored more carbon in deeper layers of the soil, while most preserved sites showed low C, N contents. The 13C in land uses ranged between -25.18%o and -21.17 %o, indicating that carbon was fixed mainly by C3 plants. It was concluded that land use changes affect C stocks, due to practices like chemical fertilization; and Alcalá soils have high potential for ecosystem services related with edaphic carbon capture.<hr/>Se estudió la relación de cambios en el uso del terreno con el C y N edáficos, en el municipio de Alcalá (región cafetera colombiana), entre 900 y 1600 m de elevación. Los suelos son Argiudolls y Melanudands y las unidades de muestreo fueron definidas según el gradiente altitudinal. Se midieron contenidos de C y N, relación C:N, densidad aparente y abundancias de 13C y 15N. Se encontraron diferencias significativas (p < 0,05) por el efecto de la altura. La zona alta mostró mayores contenidos de C (37,06-42,88 t ha-1) y N (3,12 - 3,86 t ha-1), mayor relación C:N (11,17 - 11,97), menor densidad aparente (0.56 - 0.65 g cm"³) y abundancia de 15N (4,59 - 5,15%o). Barbechos y monocultivos almacenaron más carbono en la parte subterránea del suelo; mientras que en sitios más conservados los contenidos de C y N fueron bajos. El 13C según los usos, fluctuó entre -25,18 y -21,27%o indicando que la mayoría del C fue fijado por plantas C3. Se concluyó que los cambios en el uso afectan el almacenamiento de C, principalmente por prácticas como fertilización con productos de síntesis química; y que los suelos de Alcalá tienen alto potencial para la prestación de servicios ecosistémicos relacionados con la captura de carbono edáfico. <![CDATA[<b>EDAPHIC MESOFAUNA COMMUNITY STRUCTURE IN ORGANIC AND CONVENTIONAL MANAGEMENT OF CRANBERRY <i>(Vaccinium </i>sp.)</b><b> PLANTATIONS</b>: <b>AN AGROECOLOGICAL APPROACH</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-27912009000300006&lng=es&nrm=iso&tlng=es The aim of the present study was to determine and compare taxa richness, abundance and diversity of the edaphic mesofauna community between plantations of cranberries (Vaccinium sp.) subjected to organic and conventional management in farms in central-south Chile (37°28'S), as also to evaluate changes produced in their diversity and abundance diversity and abundance, as result of the change from conventional to organic management. In July 2006 two farms were chosen, one with one year under organic management (OM1) and a second one under six years of certified organic management (OM6). Each farm was divided in four quadrants, each one with a surface of 2,500 m . In each quadrant was extracted one sample with six replicas of 188.5 cm³ each. Samples were processed in the laboratory using the Berlesse-Tullgren system for the extraction of mesofauna and the subsequent counting and identification of specimens. To compare the organic managed plantation, it was selected a farm under conventional management (CM) with similar climatic and edaphic conditions. On each parcel, taxa richness, abundance, alpha (a) diversity, dominance and beta (P) diversity were determined. Significant differences between diversity values were determined with Student's t test (a = 0.05). It is concluded that taxa richness is similar in all plantations, independent of agricultural management, whereas abundance of each taxon individually is different between both types of management. There are significant differences in diversity between the organic plantations (OM1 versus OM6) and between the conventional (CM) versus organic plantations (P<0.05). Qualitative (taxocenotic) and quantitative (biocenotic) similarity recorded in the edaphic communities from both types of plantation management may be explained by soil type and climate similarity, as well as by the homogeneity of the edaphic ecosystem. <![CDATA[<strong>SEWAGE SLUDGE LEVELS ON THE DEVELOPMENT AND NUTRITION OF SUNFLOWER PLANTS</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-27912009000300007&lng=es&nrm=iso&tlng=es This study aimed to evaluate the effect of substituting chemical nitrogen (N) fertilization for equivalent N levels from sewage sludge of Wastewater Treatment Plant (WTP) on sunflower plant development. Nutrient levels in physiologically mature leaves and seeds, besides nutrient exportation during a 130-day assay, were also assessed. The experiment was carried out in 100 m² permanent plots at Sao Manuel Farm, which belongs to School of Agronomical Sciences, Sao Paulo State University-UNESP, Botucatu, Sao Paulo State, Brazil. The farm is located in the municipality of Sao Manuel, Sao Paulo State. Experimental design was in randomized blocks including 5 treatments and 5 replicates. Treatments were: Tl - chemical N fertilization according to the recommendation for the culture; T2 - 50% N from sewage sludge and 50% N from chemical fertilization; T3 - 100% N from sewage sludge; T4 - 150% N from sewage sludge; T5 - 200% N from sewage sludge. For all treatments, equal amounts of P and K fertilization were applied. Treatments differed for plant height from 21 to 64 days, stem diameter from 28 to 57 days, and leaf number from 21 to 38 days. Seed nutrient levels slightly varied; however, the quantities of exported N, P, Mg, Fe and Zn varied as sewage sludge levels increased.