Aplicación de métodos geofísicos al estudio del suelo

[Resumen]La sostenibilidad de la productividad agrícola y forestal depende de las propiedades y la buena calidad del suelo. La variabilidad de las propiedades del suelo es de interés, puesto que realizando un manejo localizado se favorece la reducción de costes de producción, aprovechándose mejor las materias primas y el uso de la maquinaria agrícola. La agricultura de precisión busca, mediante técnicas de aplicación localizada de fertilizantes, fitosanitarios y nuevos métodos de medida de las propiedades de los suelos, un mayor rendimiento económico de la zona cultivada así como un menor impacto ambiental. Esta tesis doctoral tiene como objetivo estudiar la variabilidad estadística y espacial de las propiedades generales del suelo y de los elementos extraídos en una parcela representativa de la Comarca de Terra Chá (creándose además mapas de variabilidad espacial de los mismos). Además, se estudian las posibles relaciones entre la conductividad eléctrica aparente (CEa) del suelo, las propiedades generales y los elementos extraídos. Se relacionan tanto las propiedades generales como los elementos extraídos con la conductividad eléctrica aparente (CEa) del suelo (horizontal y vertical). La toma de muestras se realizó una vez obtenida la red de muestreo optimizado en función de las medidas de CEa. Se obtuvieron 80 puntos de muestreo a profundidad 0 a 20 cm y >20 cm en el Horizonte A. En estos puntos se muestrearon las siguientes propiedades generales: MO, pH, Ca, P, Mg, K, Al, H+Al, SB, CIC, V, arcilla, limo y arena. Los elementos fueron extraídos en esos puntos mediante dos métodos, con Mehlich-3 (Ca, P, K, Fe, Mn, Zn, Cu, Cd, Cr, Ni y Pb) y con DTPA (Fe, Mn, Zn, Cu, Cd, Cr, Ni y Pb). Las propiedades generales, en cuanto sus coeficientes de variación, se ordenan de la siguiente forma: pH20 cm no Horizonte A. Nestes puntos foron amostradas as seguintes propiedades xerais: MO, pH, Ca, P, Mg, K, Al, H+Al, SB, CIC, V, arxila, limo e area. Os elementos foron extraídos nestes puntos mediante dous métodos, con Mehlich-3 (Ca, P, K, Fe, Mn, Zn, Cu, Cd, Cr, Ni e Pb) e DTPA (Fe, Mn, Zn, Cu, Cd , Cr, Ni e Pb). Os coeficientes de variación das propiedades xerais ordénanse do seguinte xeito: pH20 cm depth, covering the whole A Horizon. Soil samples wer analyzed for: OM content, pH, Ca, Mg, K, Al, H+Al, SB, CEC, V, clay, silt and sand. Extractions have been performed using two different methods, Mehlich-3 (Ca, P, K, Fe, Mn, Zn, Cu, Cd, Cr, Ni y Pb) and DTPA (Fe, Mn, Zn, Cu, Cd, Cr, Ni y Pb). Coefficients of variation of general soil properties ranked as: pH<ECH<CEC<OM<H+Al<ECV<SB <K<Ca<V<Al<Mg. Moreover, coefficients of variation of elements extracted using Mehlich-3 ranked as: pH<ECH<CEC<OM<H+Al<ECV<SB<K<Ca<V<Al<Mg. When using DTPA, coefficients of variation ranked as: Cd<Ni<Fe<Cu<Pb<Mn<Zn<Cr. Significant lineal correlations have been found between ECH to OM (negative), clay, sand (negative), PMehlich-3 and NiDTPA. In turn, ECV was correlated to OM (negative), Ca, P , SB, clay, sand (negative) FeDTPA, CdDTPA, NiDTPA, PbDTPA, CdMehlich-3, NiMehlich-3 y PbMehlich-3. Both ECH and ECV showed a strong spatial dependence, which was modelled by a semivariogram nugget effect plus a spherical component. Spatial dependence was also demonstrated by 10 out of the 14 soil properties studied and it was strong for OM, pH, P, clay and sand; in these cases, patterns of spatial dependence were modelled by a nugget effect plus five spherical and five exponential semivariograms. When using Mehlich-3, 10 out of the 11 extracted elements showed spatial dependence, which was modelled by a nugget effect plus 8 exponential and 3 spherical models; the patterns of spatial dependence were stronger for K, Cd, Fe, P, Pb, Cr, Cu and Mn. When using DTPA, 4 out of the extracted elements also showed spatial dependence, which was modelled by three Exponential models and one Gaussian model; patterns of spatial were stronger for Mn and Fe

Levels of Cd, Cr, Ni y Pb in a agricultural soil over quaternary sediments extracted by Mehilich-3 and DTPA

[Resumen] El objetivo de este estudio fue determinar las concentraciones de Cd, Cr, Ni y Pb extraíbles en un suelo de pradera de 10 ha en Castro Ribeira de Lea, Lugo (España). Se recogieron 80 muestras de suelo en dos capas del horizonte A, de 0 a 20 cm de profundidad y desde 20 cm hasta el límite del horizonte estudiado; que presentó un rango de 25 a 48 cm. Las extracciones se realizaron mediante dos soluciones: Mehlich-3 y DTPA. La solución Mehlich-3 extrajo concentraciones más altas para los cuatro metales pesados en las dos profundidades del suelo muestreadas. La mayor concentración obtenida fue el PbMehlich-3 (3,54 mg·kg-1 a 0-20 cm y 2,67 mg·kg-1 a > 20 cm). Las concentraciones medias de Ni, Cr y Cd extraídas con Mehlich-3 no fueron superiores a 0,30 mg·kg-1, en tanto que las concentraciones extraídas con DTPA fueron incluso menores, siendo inferiores a 0,16 mg·kg-1. Las correlaciones más fuertes entre los metales pesados y propiedades generales del suelo fueron NiDTPA - pH; Ni- Mehlich-3 - pH a >20 cm y 0-20 respectivamente; NiDTPA- Arcilla a 0-20 cm, CrMehlich-3 y CdMehlich-3 - MO a 0-20 cm. Las correlaciones de los metales pesados con el pH del suelo fueron negativas, obteniéndose mayores concentraciones al aumentar la acidez del suelo. Si bien, las concentraciones de metales pesados registrados en la pradera estudiada están por debajo de los niveles considerados peligrosos para suelos agrícolas. Por lo tanto, los resultados obtenidos sugieren que las actividades agrícolas (fertilización, uso de pesticidas, etc.) fueron adecuadas en este área[Abstract The aim of this study was to determine the concentrations of extractable Cd, Cr, Ni and Pb in soils samples from a 10 ha grassland field at Castro Ribeira de Lea, Lugo (Spain). Eighty soil samples were collected at two layers of the A horizon, from 0 to 20 cm depth and from 20 cm to a variable depth defined by the boundary of the studied surface horizon, which ranged from 25 to 48 cm. Extractions of the studied elements were performed using two different solutions: Mehlich-3 and DTPA. The Mehlich-3 solution extracted higher concentrations for all the four heavy metals of interest at the two soil depths analyzed. The highest concentration recorded was for PbMehlich-3 (3.54 mg·kg-1 at 0 - 20cm and 2.67 mg·kg-1 at >20cm depths). However, mean Ni, Cr, and Cd concentrations extracted with Mehlich 3 were not higher than 0,30 mg·kg-1, while concentrations extracted with DTPA still were smaller, below 0.16 mg·kg-1- The strongest correlations between extractable concentrations of heavy metals and soil general properties were NiDTPA - pH; NiMehlich-3 - pH at >20 cm and 0-20 respectively; NiDTPA - Clay at 0-20cm, CrMehlich-3 and CdMehlich-3 - OM at 0-20 cm. Correlations with soil pH were negative, showing increasing extractability with increasing soil acidity. This notwithstanding, in our study case, the concentrations of heavy metals in the studied soil under grassland were far from levels, which are considered could be hazardous for agricultural soils. Thus, the results obtained suggest that the agricultural management (fertilizers, pesticides, etc) was appropriate in this area

Sustainability of Groundwater Resources of Weathered and Fractured Schists in the Rural Areas of Galicia (Spain)

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG.[Abstract] Water supply deficits in droughts, groundwater pollution and climate change are the main challenges for the sustainability of groundwater resources from hard-rock aquifers in rural areas of Galicia (Spain). Here, we address the sustainability of groundwater resources of weathered and fractured schists in the rural areas of the Abegondo municipality. The conceptualization of the hydrogeology of the study area includes: (1) The weathered schist (regolith), (2) The decompressed highly fractured schist layer; and (3) An underlying slightly fractured schist. Groundwater flows mostly through the regolith and the highly fractured rock. Rainfall infiltration is the source of aquifer recharge. Groundwater discharges in seepage areas, springs and along creeks and valleys. The water table is generally shallow and shows seasonal oscillations of up to 4 m. The equivalent transmissivity of the regolith and the highly fractured schist ranges from 15 to 35 m2/days. The electrical resistivity tomography identifies a shallow water table and attests that the contact of the highly fractured schist and the slightly fractured schist is highly heterogeneous. Groundwater resources were quantified with a hydrological water balance model. The mean annual recharge is about 185 mm. Groundwater recharge at the end of the twenty-first century could decrease from 6 to 10% due to climate change. The decline in groundwater table could aggravate the shortages during droughts. Groundwater quality data show bacteriological and nitrate contamination due to the poor management of the manure in the fields and occasional discharges of slurry from pig and mink farms. Groundwater management and protection actions are proposed to prevent groundwater pollution and achieve a sustainable groundwater supply in the study area.Open Access funding provided thanks to the CRUE-CSIC agreement (Universidade da Coruña/CISUG) with Springer Nature. This study is funded by LIFE program of the European Commission, LIFE12 ENV/ES/000557, Ministerio de Ciencia e Innovación, PID2019-109544RB-I00, Consellería de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia, ED431C 2017/67Xunta de Galicia; ED431C 2017/6

Niveles de Cd, Cr, Ni y Pb extraídos mediante Mehilich-3 y DTPA en un suelo agrícola sobre sedimentos cuaternarios

The aim of this study was to determine the concentrations of extractable Cd, Cr, Ni and Pb in soils samples from a 10 ha grassland field at Castro Ribeira de Lea, Lugo (Spain). Eighty soil samples were collected at two layers of the A horizon, from 0 to 20 cm depth and from 20 cm to a variable depth defined by the boundary of the studied surface horizon, which ranged from 25 to 48 cm. Extractions of the studied elements were performed using two different solutions: Mehlich-3 and DTPA. The Mehlich-3 solution extracted higher concentrations for all the four heavy metals of interest at the two soil depths analyzed. The highest concentration recorded was for PbMehlich-3 (3.54 mg·kg-1 at 0 - 20cm and 2.67 mg·kg-1 at &gt;20cm depths). However, mean Ni, Cr, and Cd concentrations extracted with Mehlich 3 were not higher than 0,30 mg·kg-1, while concentrations extracted with DTPA still were smaller, below 0.16 mg·kg-1- The strongest correlations between extractable concentrations of heavy metals and soil general properties were NiDTPA - pH; NiMehlich-3 - pH at &gt;20 cm and 0-20 respectively; NiDTPA - Clay at 0-20cm, CrMehlich-3 and CdMehlich-3 - OM at 0-20 cm. Correlations with soil pH were negative, showing increasing extractability with increasing soil acidity. This notwithstanding, in our study case, the concentrations of heavy metals in the studied soil under grassland were far from levels, which are considered could be hazardous for agricultural soils. Thus, the results obtained suggest that the agricultural management (fertilizers, pesticides, etc) was appropriate in this area.El objetivo de este estudio fue determinar las concentraciones de Cd, Cr, Ni y Pb extraíbles en un suelo de pradera de 10 ha en Castro Ribeira de Lea, Lugo (España). Se recogieron 80 muestras de suelo en dos capas del horizonte A, de 0 a 20 cm de profundidad y desde 20 cm hasta el límite del horizonte estudiado; que presentó un rango de 25 a 48 cm. Las extracciones se realizaron mediante dos soluciones: Mehlich-3 y DTPA. La solución Mehlich-3 extrajo concentraciones más altas para los cuatro metales pesados en las dos profundidades del suelo muestreadas. La mayor concentración obtenida fue el PbMehlich-3 (3,54 mg·kg-1 a 0-20 cm y 2,67 mg·kg-1 a &gt; 20 cm). Las concentraciones medias de Ni, Cr y Cd extraídas con Mehlich-3 no fueron superiores a 0,30 mg·kg-1, en tanto que las concentraciones extraídas con DTPA fueron incluso menores, siendo inferiores a 0,16 mg·kg-1. Las correlaciones más fuertes entre los metales pesados y propiedades generales del suelo fueron NiDTPA - pH; NiMehlich-3 - pH a &gt;20 cm y 0-20 respectivamente; NiDTPA- Arcilla a 0-20 cm, CrMehlich-3 y CdMehlich-3 - MO a 0-20 cm. Las correlaciones de los metales pesados con el pH del suelo fueron negativas, obteniéndose mayores concentraciones al aumentar la acidez del suelo. Si bien, las concentraciones de metales pesados registrados en la pradera estudiada están por debajo de los niveles considerados peligrosos para suelos agrícolas. Por lo tanto, los resultados obtenidos sugieren que las actividades agrícolas (fertilización, uso de pesticidas, etc.) fueron adecuadas en este área

Comparing effects of tillage treatments performed with animal tractionon soil physical properties: preliminary experimental results

La compactación del suelo es causada por las fuerzas que compresión aplicadas al suelo mediante la maquinaria agrícola así como las operaciones de labrado, siendo particularmente preocupantes cuando el suelo está húme- do y sufre más riesgos de deformación. La tracción animal (e incluso la humana) también puede causarla, si bien no ha sido estudiada en profundidad. Hoy en día la tracción animal surge como alternativa sostenible a la meca- nizada, en especial en áreas de montaña. Este estudió se llevo a cabo para evaluar el impacto en la compacta- ción del suelo del laboreo utilizando tracción mecánica y tracción animal. La parcela estudiada está situada en Vale de Frades, NE de Portugal. En ella se aplicaron los tratamientos en sub-parcelas (30x3m), que consistían en dos pases con tractor, un par de vacas y un par de burros; siendo los aperos de volteo (arado romano) y de corte (cultivador y escarificador). Se tomaron 120 muestras de suelo antes y después de las labores para estu- diar diferentes propiedades físicas del suelo: densidad aparente, porosidad y conductividad hidráulica.Los resul- tados de este ensayo si bien parecen mostrar la tracción animal como una alternativa sostenible a la motoriza- ción, no son todavía concluyentes, haciendo necesarios estudios futuros.info:eu-repo/semantics/publishedVersio

Addition of amendments to restore a compacted soil under no-tillage system

The addition of organic and inorganic amendments can improve soil structure and reduce soil compaction. In this context, this study aimed to evaluate whether the application of amendments reduces penetration resistance (PR) in the short term and describe the spatial variability of PR in the surface horizon of an Aquic Argiudoll under no-tillage in northeast Argentina. Four treatments, consisting of surface applications of 7.5 Mg ha−1 poultry litter (PL), 3.0 Mg ha−1 gypsum (G), the combination of PL+G, and untreated control (T), were arranged in a complete randomized block design with three replications. Two more treatments were added to the experiment 12 months later, consisting of PL reapplications on half of the surface of the PL+G and PL treatments (PL+G+PL and PL+PL, respectively) in a split-plot design with three replications in 4×20-m plots. PR was determined in the field with an Eijkelkamp penetrologger following a 2-m long transect perpendicular to the sowing direction at 10 different spots separated 0.2 m from each other. The spatial variability was quantified for each treatment using semivariograms. The highest PR was observed in the T treatment (1.96 MPa) and the lowest PR in PL+G+PL (0.21 MPa). All treatments showed a high spatial dependence (94.9 to 99.9%). Treatments with PL reapplication (PL+PL and PL+G+PL) showed profiles with lower PR and more homogeneous kriging maps. PL reapplication on PL treatments showed no effects on PR values. However, PL reapplication on the PL+G treatment led to positive effects in all PR ranges. Thus, the PL+G+PL treatment, which had the highest PR values, showed a decrease in PR from 54.17 to 6.65% with the reapplication 12 months later. The addition of organic and inorganic amendments reduced specific compacted soil areas on the surface horizon of an Aquic Argiudoll under no-tillage.EEA ParanáFil: Barbieri, Rayner Sversut. Faculdades Associadas de Uberaba. Departamento de Zootecnia; BrasilFil: Gabioud, Emmanuel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná; ArgentinaFil: Wilson, Marcelo German. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná; Argentina.Fil: Sasal, María Carolina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná; ArgentinaFil: Seehaus, Mariela. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná; ArgentinaFil: García-Tomillo, Aitor. Advanced Scientific Research Center; EspañaFil: Silva, Tatiane Carla. Universidade Estadual Paulista “Júlio de Mesquita Filho”. Departamento de Fitossanidade, Engenharia Rural e Solos; BrasilFil: Montanari, Rafael. Universidade Estadual Paulista “Júlio de Mesquita Filho”. Departamento de Fitossanidade, Engenharia Rural e Solos; Brasi

Uso da krigagem na avaliação da variabilidade espacial de atributos físicos do solo com diferentes tipos de preparo inicial

A técnica geoestatística, moderada pelo semivariograma e krigagem, permite obter um diagnóstico específico dentro de um talhão, que poderão requerer intervenções de manejos específicas. Tais informações são importantes para tomadas de decisão aquando do preparo do solo. Assim, o objetivo desse estudo foi avaliar a variabilidade espacial de algumas propriedades físicas do solo antes e depois de seu preparo inicial com diferentes trações e implementos agrícolas. O ensaio foi instalado na Quinta do Poulão da Escola Superior Agrária de Bragança, Portugal (41°46’49.53’’N 6°47’57.50’’O) em um Fluvisssolo Êutrico de aluvião. O experimento foi conduzido no mês de janeiro de 2018 em umaárea experimental com a cultura de milho (Zea mays) e foi dividida em 6 subparcelas de 60 m2: Tração animal + Arado (T1); Tração animal + Escarificador (T2); Tração animal + Arado + Escarificador (T3); Tração motorizada + Arado (T4); Tração motorizada + Escarificador (T5); Tração motorizada + Arado + Escarificador (T6). Foi confeccionada uma malha geoestatística composta por 48 pontos amostrais. Foi analisada a densidade do solo (DS), resistência do solo à penetração de raízes (RP) e Umidade gravimétrica (UG) em três profundidades: 1. 0‐0,05 m; 2. 0,05‐0,10 m; 3. 0,10‐0,20 m. Foi avaliado o grau da dependência espacial (ADE) e, por meio da krigagem, os mapas detalhados da variabilidade espacial dos atributos. A DS3, UG1, UG2 e UG3 apresentaram efeito pepita puro, ou seja, não mostraram dependência espacial entre os pontos amostrais. A DS2 mostrou maior r2 (0,710) e a RP3 maior ADE (85,5%). Os mapas tornam evidente que as subparcelas T2 e T5 estavam mais compactadase o preparo apenas com escarificador não influenciou os atributos estudados. Já a combinação dos implementos com tração motorizada revelou um efeito expressivo ao diminuir a densidade do solo na profundidade de 0‐0,10 m. Conclui‐se que o tratamento com tração motorizada e escarificador teve influência mais evidente nos atributos estudados na profundidade de 0‐0,10 m e que, em futuros manejos precisos, as subparcelas T2 e T5 devem receber maiores preparos, com uso dos dois implementos.info:eu-repo/semantics/publishedVersio

Análise de atributos físicos do solo em função de seu preparo com diferentes trações e implementos agrícolas

O manejo do solo com máquinas em pequenas áreas pode ser mais difícil operacionalmente do que o trabalho com animais, porém, existe a carência de estudos que indiquem diferenças e consequências nas propriedades físicas do solo entre os dois tipos de preparo. Assim, o objetivo desse estudo foi avaliar a influência do preparo do soloem algumas de suas propriedades físicas por meio de tração animal e motorizada com arado e escarificador. O ensaio foi instalado na Quinta do Poulão do Instituto Politécnico de Bragança, Portugal (41°46’49.53’’N 6°47’57.50’’O) em um Fluvisssolo Êutrico de aluvião. O experimento foi conduzido no mês de janeiro de 2018 em umaárea experimental com restolho da cultura de milho (Zea mays) e foi dividida em 6 subparcelas de 60 m2 com os seguintes tratamentos: Tração animal + Arado (T1); Tração animal + Escarificador (T2); Tração animal + Arado + Escarificador (T3); Tração motorizada + Arado (T4); Tração motorizada + Escarificador (T5); Tração motorizada + Arado + Escarificador (T6). Utilizou‐se o delineamento experimental em sistema fatorial duplo (3x2), com quatro repetições, e depois submetidas ao teste de Tukey a 5%. Foi analisada a densidade do solo (DS), resistência do solo à penetração de raízes (RP) e Umidade gravimétrica (UG) antes e depois do preparo do solo, em três profundidades: 1. 0‐0,05 m; 2. 0,05‐0,10 m; 3. 0,10‐0,20 m. Antes do preparo do solo não se registaram diferenças significativas entre tratamentos, mostrando que a área experimental era uniforme quanto às propriedades analisadas. Depois do preparo do solo, o T6 apresentou menor DS1 (1,03 g.cm‐3; p<0,05) e o T2, a maior (1,50 g.cm‐3; p<0,05). A média geral da RP1 mostrou melhor resultado pela tração motorizada (0,72 MPa e 0,40 MPa para tração animal e tração motorizada, respectivamente; p<0,05). A UG não apresentou diferenças significativas depois dos preparos realizados. O estudo demonstrou que a tração mecânica com utilização dos dois implementos foi mais eficiente na descompactação e preparo do solo na camada de 0‐0,05 m, uma vez que o escarificador traçado pelo animal não teve força para penetrar no solo.info:eu-repo/semantics/publishedVersio

Effects of machinery trafficking in an agricultural soil assessed by electrical resistivity tomography (ERT)

Soil compaction is a serious problem, which is aggravated due to its difficulty to locate and reverse. Electrical resistivity tomography (ERT) is a non-invasive geophysical method that can be used to identify compacted areas, soil horizon thickness and assess soil physical properties. This study assesses the relationship between ERT and soil compaction. Data were collected on a 4-m transect in a fallow plot located at Braganca (Portugal). Measurements were performed before and after tillage and tractor passage. Soil samples at different depths (0-0.05, 0.05-0.1 and 0.1-0.2 m depth) were taken to determine: soil bulk density, porosity, saturated hydraulic conductivity and soil water content. The effect of tillage and tractor passage was more significant on the first 0.05 m depth. In the wheel track areas, ERT suffered a reduction of about 40%, saturated hydraulic conductivity decreased by 70% and bulk density increased by 24%. These results proved that ERT can be a useful tool for assessing soil compaction.Authors thank the “Agrupación Europea de Cooperación Territorial Galicia - Norte de Portugal” (Programa IACOBUS) for the funding. We also thank Dr. José M. Mirás-Avalos, from the University of Santiago de Compostela, for his useful comments on the manuscript.info:eu-repo/semantics/publishedVersio

X Conference on Soil Use and Management: Soil and Water Resources Sustainable Management

Volumen recopilatorio de los resúmenes de las ponencias presentadas al X Congreso sobre Uso y Manejo del Suelo (UMS): Gestión Sostenible y Recursos Hídricos, celebrado en A Coruña los días 16-18 de noviembre de 2020, organizado por el Grupo AQUATERRA: Gestión Sostenible de los Recursos Hídricos y del Suelo, el Centro de Investigaciones Científicas Avanzadas (CICA) y la Facultad de Ciencias de la Universidad de A Coruña