Soil organic matter fractions under long-term conservation tillage in rainfed Aragon (NE Spain)

1 Pag.Peer reviewe

TDR-LAB 2.0: Improved TDR software for soil water content and electrical conductivity measurements

Trabajo presentado en las XI Jornadas de Investigación en la Zona No Saturada del Suelo celebradas en Lugo del 6 al 8 de noviembre de 2013.[ES]: La técnica de Reflectometría de Dominio Temporal (TDR) permite estimar la humedad (θ) y la conductividad eléctrica aparente del suelo (σa). Esta comunicación presenta una nueva versión del programa TDR-Lab para la medida de θ y σa. El TDR-Lab 2.0 es compatible con tres ecómetros TDR diferentes y puede conectarse a multiplexores SDMX50 (Campbell Sci). Puede estimar θ y σa por métodos gráficos y numéricos y incluye nuevas aplicaciones para la medida de niveles de agua, potencial mátrico o conductividad eléctrica de la solución del suelo. Está disponible en una versión ligera que trabaja con ficheros XML y una versión completa que centraliza los datos en una base SQL. Una robusta interface de importación-exportación de datos permite comunicar ambas versiones.[EN]: Time Domain Reflectometry (TDR) is a widely used technique that allows real time estimation of soil volumetric water content (θ), and bulk electrical conductivity (σa). This work presents an enhanced release of TDR-Lab, software which controls instrumentation for measurements of θ and σa. TDR-Lab 2.0 supports three different TDR equipments and can be connected to a multiplexing system (SDMX50, Campbell Sci). Graphical or numerical methods can be used for the estimation of θ and σa. Additional features to carry out water-surface-level measurements such as matric potential and soil solution electrical conductivity are also available. A little and a full release, for field and laboratory applications have been developed. The light version works with XML-files instead of the SQL database engine of the extended TDRLab. A robust import/export graphical user interface facilitates transferring projects between the centralized SQL database and XML files.This research was supported by the Ministerio de Educación y Ciencia of Spain (grant AGL2010-22050-C03-02) and DGA- Obra social La Caixa (Grants: 2012/ GA LC 074).Peer reviewe

No laboreo en agrosistemas de secano en Aragón: efectos a largo plazo en el almacenamiento de carbono orgánico y en la estructura del suelo

201 Pags.- Tabls.- Figs.[ES] El objetivo principal de esta Tesis Doctoral ha sido evaluar la capacidad de los sistemas agrícolas basados en NT para almacenar y estabilizar OC y mejorar el estado físico del suelo en diferentes zonas de cereal de secano en Aragón. En una primera etapa, un estudio de localización y caracterización de campos comerciales de NT mostró la diversidad de prácticas de manejo que el agricultor realiza en sus campos (diferente manejo de residuos de cosecha, de sistemas de cultivo y rotaciones, de aplicación de purines, etc.), reflejando la realidad de la agricultura de conservación en la región. Con el objetivo de profundizar en el objetivo general del trabajo de Tesis, se realizó una segunda selección de seis sitios de estudio, localizados en diferentes zonas agroclimáticas de la región, en los que se compararon pares de suelos adyacentes bajo NT y laboreo convencional (CT), y un tercer suelo inalterado con vegetación natural (NAT).Los resultados mostraron que el contenido de OC en los primeros 20 cm de suelo fue, como media, un 20% superior bajo NT que bajo CT. Las mayores ganancias se obtuvieron en los campos de NT de mayor duración y/o manejados con prácticas que conllevaban un mayor aporte de biomasa al suelo. Sin embargo, esta ganancia se redujo o se invirtió a mayor profundidad de tal forma que, considerando el horizonte de 0-40 cm, el potencial del NT para almacenar OC fue similar o sólo ligeramente superior al del CT.[EN] The main objective of this PhD Thesis has been to assess the capacity of NT-based cropping systems to accumulate and stabilize OC and improve the physical condition of the soil in different cereal production areas of Aragon. In a first step, a study of localization and characterization of commercial fields of NT showed the diversity of management practices used by farmers in their fields (different crop residue management, cropping system and rotation, manure application, etc.), reflecting the reality of the conservation agriculture in Aragon. In order to deepen the overall goal of the thesis, a second selection of six study sites was made where pairs of adjacent soils under NT and conventional tillage (CT) were compared. In all sites, a nearby undisturbed soil under native vegetation (NAT) was included.The results showed that the OC content in the first 20 cm of soil was, on average, 20% higher under NT than under CT. The highest contents were obtained in the NT fields of longer duration and/or managed with practices that enhance the return of more crop biomass to the soil. However, this gain was reduced or inverted in the deeper soil layers so that, taking into account the whole soil profile (0-40 cm), the potential of NT to store OC was similar or only slightly higher than that of CT.El presente trabajo de investigación se ha realizado gracias a una Ayuda Predoctoral de Formación de Personal Investigador (FPI), del Ministerio de Ciencia e Innovación, asociada al Proyecto de Investigación AGL2007-66320-C02-02.Peer reviewe

No tillage effect on water retention characteristics of soil aggregates in rainfed semiarid conditions

1 Pag.The study was carried out in a silty clay loam soil of semiarid Aragon (NE Spain). Two tillage systems were compared: no tillage (NT) and conventional tillage with mouldboard plough (CT). The results show the suitability of NT to reduce the risk of soil crusting and compaction in agricultural lands of Aragón.Peer reviewe

Dynamics of aggregate destabilization by water in soils under long-term conservation tillage in semiarid Spain

33 Pags., 4 Tabls., 4 Figs. The definitive version is available at: http://www.sciencedirect.com/science/journal/03418162Due to particular soil and climate conditions and inappropriate agricultural practices, Aragon (NE Spain) is a region prone to land degradation by water erosion. For this reason, the adoption of conservation tillage systems has been encouraged as an alternative to preserve soil and water in this region. However, little information concerning soils on which these techniques are applied is available. The main objectives of this study were to assess the effect of long-term no tillage (NT) on wateraggregate stability in five different cereal production areas of Aragon and identify the main mechanisms involved on aggregate breakdown. The study was conducted under on-farm conditions where pairs of adjacent fields under NT and conventional tillage (CT) were compared. In all cases, a nearby undisturbed soil under native vegetation was included. Soils were slightly to highly calcareous with medium textures ranging from sandy loam to silty clay loam. Results indicate that NT increased surface aggregate stability with respect to CT systems through lower soil disturbance and higher organic carbon (OC) content at the soil surface (0–5 cm depth). Slaking was the dominant disaggregation process of the cultivated soils, representing 40–80% of total soil disruption, and was strongly and negatively affected by aggregate-associated OC. This soil property together with the silt content (weak and positive effect) explained more than 80% of the slaking variation. Swelling and clay dispersion were less frequent processes and their occurrence seemed to be associated with high silt and CaCO3 contents. This study shows that, under the rainfed conditions of semiarid Aragon, NT reduces the susceptibility of soil surface to crusting and water erosion as compared to CT systems.This research was supported by the Comisión Interministerial de Ciencia y Tecnología of Spain (Grants AGL2010-22050-CO3-02/AGR and AGL2007-66320-C02-02/AGR) and the European Union (FEDER funds). N. Blanco-Moure was awarded with a FPI fellowship by the Spanish Ministry of Science and Innovation.Peer reviewe

Malleable disc base for direct infiltration measurements using the tension infiltrometry technique

19 Pags. The definitive version, with 2 Tabls. and 6 Figs., is available at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1099-1085The correct use of the tension disc infiltrometer requires the membrane of the disc base to be completely in contact with the soil surface. To achieve this contact, a thick layer of sand is commonly placed between the soil surface and the disc base. This paper presents an alternative disc (MDB), which, by incorporating a malleable membrane, allows direct infiltration measurements without using a contact sand layer. Infiltration curves obtained with this new design in a soil under three different tillage management treatments were compared with the corresponding curves obtained with a conventional disc (CDB) that uses a contact sand layer. The cumulative infiltration curves measured with CDB were analysed by the differentiated linearization (DL) method, and the corresponding curves obtained with MDB were analysed using both the DL and the cumulative linearization (CL) models. The values of hydraulic conductivity (K0) and sorptivity (S0) estimated with CDB were also compared with those obtained with MDB. Finally, the cumulative infiltration curves measured with CDB and MDB were compared with the corresponding modelled function for the respective K0 and S0 values calculated with the CL and DL models. The results show that, compared with CDB without a contact sand layer, MDB allows complete soil surface wetting even when non-smoothed soil surfaces are used. The CDB, which yielded average K0 values 18% lower than those estimated with MDB, gave the highest values of standard error for the hydraulic parameters calculated. Furthermore, the subjective method employed in the CDB-DL technique, which requires the first points of the differential infiltration line corresponding to the sand layer to be manually removed, introduces additional uncertainties in estimating S0 and K0. Comparison between the modelled and measured infiltration curves demonstrates that the DL or CL methods applied to MDB gave excellent estimates of S0 and K0.This research was supported by the Ministerio de Ciencia e Innovación of Spain (grant AGL2010-22050-C03-02) and by the Aragón regional government and La Caixa (grant GA-LC020/2010).Peer reviewe

Efeito a longo prazo do plantio direto em frações de matéria orgânica do solo no sequeiro de Aragon (NE Espanha)

10 Pag., 1 Fig. The definitive version is available at: http://sjss.universia.net/[EN] This paper assesses the long-term effect of no-tillage (NT) on soil organic carbon (OC) content and its distribution among different organic matter fractions in rainfed agrosystems of Aragón (NE Spain). Adjacent fields of NT, conventional tillage (CT) and natural soils (NAT) were compared in three different cereal production areas. In the soil surface, the higher OC content found in the NAT soils was due to the particulate organic matter. In the case of agricultural soils, in general, the fractions responsible for the OC increase under NT were the fine particulate organic matter and the mineral-associated organic matter occluded within stable microaggregates.[ES] En este trabajo se evalúa el efecto a largo plazo del no laboreo (NT) en el contenido de carbono orgánico del suelo (OC) y su distribución en diferentes fracciones de materia orgánica en agrosistemas de secano en Aragón (NE España). En tres diferentes zonas cerealistas se compararon campos adyacentes de NT, laboreo tradicional (CT) y suelo natural (NAT). En la superficie del suelo, el mayor contenido en CO encontrado en los suelos NAT se debió a la materia orgánica particulada. En el caso de los suelos agrícolas las fracciones responsables del incremento de OC en NL fueron, en general, la materia orgánica particulada fina y la fracción órgano-mineral de los microagregados estables.[PO] Este trabalho avalia o efeito a longo prazo do plantio direto (NT) no conteúdo de carbono orgânico no solo (OC) e a sua distribuição em diferentes frações da matéria orgânica em sistemas agrícolas de sequeiro em Aragon (NE Espanha). Campos adjacentes do NT, plantio convencional (CT) e solos naturais (NAT) foram comparados em três diferentes áreas de produção de cereais. Na superfície do solo, o maior teor de OC encontrado nos solos NAT deveu-se à matéria orgânica particulada. No caso dos solos agrícolas, as frações responsáveis pelo aumento de OC em NL foram, em geral, à matéria orgânica particulada fina e a fração organo-mineral de microagregados estáveis.This research was supported by the Comisión Interministerial de Ciencia y Tecnología of Spain (Grants AGL2007-66320-CO2- 02/AGR and AGL2010-22050-CO3-02/AGR) and the European Union (FEDER funds). The first author was awarded with a FPI fellowship by the Spanish Ministry of Science and Innovation.Peer reviewe

Tensile strength and organic carbon of soil aggregates under long-term no tillage in semiarid Aragon (NE Spain)

El pdf del artículo es la versión pre-print.Tensile strength (TS) of soil aggregates is recognized as a useful parameter to detect structural changes associated with soil management. Although conservation tillage has been encouraged as a management alternative to preserve soil and water resources in semiarid Aragon (NE Spain), little information concerning soils on which these techniques are applied is available for this region. The main objective of this study was to assess the effect of long-term no tillage (NT) on TS, rupture energy (E) and organiccarbon (OC) of soil surface aggregates (0–5 cm depth) in five different cereal production areas of Aragon. In four of the sites, the study was conducted under on-farm conditions where pairs of adjacent fields under NT and conventional tillage (CT) were compared. In the last site, the study was carried out in research plots from a long-term tillage experiment where a third tillage treatment was also considered (reduced tillage). In all cases, a nearby undisturbed soil under native vegetation was included. Results indicate that NT reduced aggregate TS and E with respect to CT systems through lower soil disturbance and higher OC content. Aggregate size (16–8, 8–4, 4–2 and 2–1 mm in diameter) and aggregate-associated OC explained 70–80% of the variation in TS and E. Strength properties varied with OC in quadratic way with minimum values at about 20 g kg− 1 of OC. This behavior can be explained by the significant interactions found between clay and OC in such a way that in the soils with the highest values of clay and OC, aggregate strength increased considerably. This study shows that, under the rainfed conditions of semiarid Aragon, NT improves soil physical conditions by reducing aggregatestrength at the soil surface. This means, for example, that NT could provide a more favorable environment for seedling emergence and root growth than the traditional practices in the area.This research was supported by the Comisión Interministerial de Ciencia y Tecnología of Spain (grants AGL2010-22050-CO3-02/AGR and AGL2007-66320-C02-02/AGR) and the European Union (FEDER funds). N. Blanco-Moure was awarded with a FPI fellowship by the Spanish Ministry of Science and Innovation.Peer reviewe

Efecto a largo plazo del no laboreo sobre fracciones de material orgánica del suelo en agrosistemas de secano en Aragón

4 Pags., 2 Tabls., 2 Figs.En este trabajo se evalúa el efecto a largo plazo del no laboreo (NL) en el contenido de carbono orgánico del suelo (C) y su distribución en diferentes fracciones de materia orgánica en agrosistemas de secano en Aragón. En 3 diferentes zonas cerealistas se compararon pares de campos adyacentes de laboreo tradicional (LT) y NL. El mayor contenido de C encontrado en la superficie del suelo bajo NL con respecto a LT se debió a la materia orgánica particulada fina (MOPf) y a la fracción mineral asociada (<53 μm) del interior de microagregados estables.Este trabajo ha sido financiado por la Comisión Interministerial de Ciencia y Tecnología de España (AGL2007-66320-CO2-02/AGR y AGL2010-22050-CO3-02/AGR) y la Unión Europea (fondos FEDER). El primer autor disfruta de una beca FPI otorgada por el Ministerio de Ciencia e Innovación.Peer reviewe

Improvement of soil physical quality with no tillage in semiarid agricultural lands of Aragon (NE Spain)

4 Pag., 5 Figs.Tensile strength (TS), water aggregate stability (WAS) and organic carbon (OC) content were measured in soil surface aggregates collected from a dryland cereal field of semiarid Aragon. Three tillage treatments were considered (conventional tillage, CT; reduced tillage, RT; and no tillage, NT) and compared with an adjacent natural soil (NAT). With respect to CT, soil physical quality was improved with adoption of NT. However, NAT soils show the best structural condition. The OC of aggregates was a key factor to explain the differences among soil management. Our results show that in semiarid Aragon, conservation tillage practices as NT can improve soil structure by enhancing soil organic carbon content.This research was supported by the Comisión Interministerial de Ciencia y Tecnología of Spain (Grant AGL2007-66320-CO2-02/AGR) and the European Union (FEDER funds). The first author was awarded a FPI fellowship by the Spanish Ministry of Science and Innovation.Peer reviewe