Fifth Symposium on cereal Physiology and Breeding

3 Pág.Fifth Symposium on cereal Physiology and BreedingPeer reviewe

Mediterranean dryland farming Effect of tillage practices on selected soil properties

It is widely accepted that conservation tillage management affords benefits to soil properties and reduces production costs; therefore these practices could be attractive to farmers from semiarid regions. The objective of this study was to assess the long-term effects of different tillage practices under semiarid conditions on macroaggregate stability (water stable aggregates, WSA), soil organic carbon (SOC), and particulate organic carbon (C-POM) content of an Alfisol from Spain. The experimental design involved a split plot and four randomized blocks in which tillage was the main factor and crop rotation (fallow-wheat-pea-barley) the secondary factor. Three tillage systems were compared no tillage (NT), minimum tillage (MT), and conventional tillage (CT). Soil samples were collected on November 2006 and October 2007. In November 2006 no significant differences in WSA were found among the tillage treatments. In October 2007, however, the mean WSA in the upper soil layer for the NT was significantly higher, 24%, that in the CT. No significant differences were seen for the subsurface layer. Under NT, the SOC and C-POM values for the surface soil layer were significantly higher than those for the other treatments on both sampling dates. At the subsurface depth, no significant differences were seen in either of these variables. The SOC and C-POM values were more homogeneous throughout the soil profile in the plowed soil than in the NT for which the corresponding values were more stratified. The results show that NT will help improve soil structure and soil fertility, which is particularly relevant to semiarid conditions like the area studied. © 2011 by the American Society of Agronomy

Assessing the cover crop effect on soil hydraulic properties by inverse modelling in a 10-year field trial

Cover cropping in agriculture is expected to enhance many agricultural and ecosystems functions and services. Yet, few studies are available allowing to evaluate the impact of cover cropping on the long term change of soil hydrologic functions. We assessed the long term change of the soil hydraulic properties due to cover cropping by means of a 10-year field experiment. We monitored continuously soil water content in non cover cropped and cover cropped fields by means of capacitance probes. We subsequently determined the hydraulic properties by inverting the soil hydrological model WAVE, using the time series of the 10 year monitoring data in the object function. We observed two main impacts, each having their own time dynamics. First, we observed an initial compaction as a result of the minimum tillage. This initial negative effect was followed by a more positive cover crop effect. The positive cover crop effect consisted in an increase of the soil micro- and macro-porosity, improving the structure. This resulted in a larger soil water retention capacity. This latter improvement was mainly observed below 20 cm, and mostly in the soil layer between 40 and 80 cm depth. This study shows that the expected cover crop competition for water with the main crop (evapotranspiration) can be compensated by an improvement of the water retention in the intermediate soil layers and a reduction of drainage loses. This may enhance the hydrologic functions of agricultural soils in arid and semiarid regions which often are constrained by water stress

Management of weed emergence and weed seed bank in response to different tillage, cropping systems and selected soil properties

The agronomic practices used to manage the soil play an important role in the maintenance of biological diversity within crop fields. Conservation agriculture technology has been extensively adopted in dry land conditions. In these systems, the relationship between soil properties and weed density and soil weed seed bank has not been explored deeply. We conducted this study in order to (1) examine the cumulative impact of tillage systems (CT, MT and NT) on weed emergence on the field; (2) test the effects of different tillage and crop systems on weed species density and diversity (Shannon's index, Pielou index and species richness) within the transient and persistent seed bank of the soil; and (3) analyse the impact of two soil parameters on weeds water stable aggregates (WSA) and particulate organic matter content (C-POM). The highest weed density was recorded in conservation tillage systems (MT and/or NT) several years after the implementation of these systems. Additionally, the cumulative effects of conservation tillage techniques were found to have increased the seed density and species diversity in soil seed bank, which was probably due to particular conditions created in the soil; a low or negligible level of soil disturbance (as is expected with MT and NT) possibly allowed seeds to keep in the soil seed bank and remain dormant, due to, among other reasons, improved water stable aggregates and organic matter content. Results from the study confirm the complexity of the matrix formed by weed-seed bank-soil. © 2016 Elsevier B.V

The distinct responses of bacteria and fungi in different-sized soil aggregates under different management practices

13 Pág. Departamento de Medio Ambiente y Agronomía​Soil aggregates can be considered massive microbial incubators. Thus, the study of the bacteria and fungi colonizing different soil aggregate fractions helps to elucidate the factors influencing the associations between microhabitats in soil aggregates and microbial functioning. The main objective of this study was to evaluate the total bacterial and total fungal abundances and soil quality-related parameters of four aggregate size fractions (>2 mm, 2–0.25 mm, 0.25–0.053 mm and 2 mm), which constituted only 16.7% (with 0.17 OC/100 g soil) under this treatment at 0–5-cm depth, compared with 50.7% (with 1.34 g OC/100 g soil) in uncultivated soil. The abundances of bacteria and fungi exhibited contrasting responses to soil management across aggregate fractions, which differed by depth. The abundance of bacteria, but not fungi, was closely related to OC and N concentrations, with higher values in macroaggregates than in microaggregates for TT and DS at 0–5 cm depth. Uncultivated soil showed no OC differences across aggregate fractions and the bacteria were distributed uniformly among them. Fungal abundance was higher in microaggregates, mainly in DS, concurrent with lower bacterial abundance. Therefore, bacteria and fungi responded differently to changes in properties at the aggregate scale induced by soil management within the soil surface horizon. Highlights: Management practices affect aggregate size distribution and their bacterial and fungal abundances Tillage reduced the OC stored in macroaggregates >2 mm by 87% compared to uncultivated soil Bacterial abundance was positively correlated with the C and N concentrations inside aggregates Fungal abundance showed an important negative correlation with the bacterial abundance.Comunidad de Madrid, Grant/Award Number: AGRISOST S2018/BAA-4330; Ministerio de Ciencia e Innovación, Grant/Award Number: GL2017-83283-C2-1-R; Community of Madrid; Spanish Ministry of Science and InnovationPeer reviewe

Análisis de la producción de maíz en España

España es un país donde la producción agrícola tiene un peso relativamente bajo en el producto interior bruto nacional (solo del 3,16%), pero con una gran importancia estratégica ya que representa más de 20 millones de toneladas de productos vegetales exportados al año, además del alto nivel de consumo interno. Dentro de esa producción, el cultivo del maíz es uno de los cultivos con mayor importancia en cuanto a superficie dentro de los sistemas de regadío. El presente estudio pretende resumir la situación actual de la producción de maíz en España en relación a la situación mundial. A día de hoy, los dos principales factores limitantes para el aumento de la superficie cultivada de maíz y el aumento de su rendimiento en España son la disponibilidad de agua y la rentabilidad económica. Por eso, este trabajo resume los avances alcanzados hasta la fecha, pero también las mejoras potenciales que permitirían mejorar su rendimiento económico sin aumentar (o incluso disminuyendo) su impacto ambiental. Estas técnicas se basan en la mejora de la eficiencia de uso de los insumos agrícolas empleados (fertilizantes, gasoil, fitosanitarios, entre otros) así como la eficiencia en el uso del agua. Para alcanzar estas mayores eficiencias se han identificado distintas técnicas como el ajuste de las dosis de agua-nutrientes-fitosanitarios, su aplicación en los momentos clave o incluso la teledetección y el uso de agricultura de precisión, todos ellos definidos en mayor detalle en este trabajo. Por eso, los agricultores que deseen seguir cultivando maíz en España, además de ser capaces de mejorar su rendimiento y reducir el impacto ambiental, deberán, sobre todo, mejorar sus márgenes de beneficio.Peer reviewe

Organic amendment vs. Mineral fertilization under minimum tillage: Changes in soil nutrients, soil organic matter, biological properties and yield after 10 years

Conservation tillage is recognized as a sustainable management practice, however its combination with organic residues application still constitutes a challenge in some areas. A field trial was established in a semiarid agro-ecosystem to study the effects of different crop nutrient sources under minimum tillage (MT). Application of organic amendments at the beginning of a five-year crop rotation (ORG treatment) was evaluated and compared to the control plot where wheat was continuously grown with traditional mineral fertilization (MIN treatment). In addition to wheat yield and biomass, several soil properties were measured (pH, soil nutrients (i.e., Olsen P, exchangeable K, and mineral N), soil organic matter (i.e., C, N, C/N ratio), potentially mineralizable nitrogen, total microbial activity and heavy metals) throughout the 10-year study. The wheat yield was significantly higher under the ORG treatment than under the MIN, although climatic conditions (e.g., rainfall) exerted a great influence too. The organic amendments increased soil nutrients content mainly right after their application but the levels were adequate for the whole crop rotation. Plots under organic amendment application did not accumulate significantly more soil organic matter than those mineral-fertilized, probably due to the low protective capacity of coarse-textured soils. The application of organic amendments under MT resulted in a promising management agro-ecosystem compared to the mineral fertilized because crop nutrients came from organic wastes, no herbicides were applied while the yields were higher.This work was funded by INIA (AT2017-003), the Ministry of Science and Innovation (RTA2017-00006-C03-01, AGL2017-83283-C2-1/2-R), the EJPSoil [CarboSeq] project (which has re ceived funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 862695), the Community of Madrid (AGRISOST-CM S2018/BAA-4330) and European Structural funding 2014-2020 (ERDF y ESF)Peer reviewe

Análisis de la producción de maíz en España

This study aims to summarize the current situation of maize production in Spain in relation to the world situation. At present, the two main constraints to increasing the area cultivated with maize and increasing its yield in Spain are the availability of water and economic profitability. For this reason, this work summarizes the progress achieved to date, but also the potential improvements that could improve their economic performance without increasing (or even decreasing) their environmental impact. These techniques require inevitably an improvement of the use efficiency of the agronomic inputs (fertilizers, diesel, pesticides…), as well as, the improvement of water use. Therefore, farmers who wish to continue growing maize in Spain, in addition to being able to improve their yields and reduce their environmental impact, must, above all, improve their production margins.El presente estudio pretende resumir la situación actual de la producción de maíz en España en relación a la situación Mundial. A día de hoy, los dos principales factores limitantes para el aumento de la superficie cultivada de maíz y el aumento de su rendimiento en España son la disponibilidad de agua y la rentabilidad económica. Por eso este trabajo resume los avances alcanzados hasta la fecha, pero también las mejoras potenciales que permitirían mejorar su rendimiento económico sin aumentar (o incluso disminuyendo) su impacto ambiental. Y estas técnicas se basan en la mejora de la eficiencia de uso de los insumos agrícolas empleados (fertilizantes, gasoil, fitosanitarios,…) así como por la eficiencia en el uso del agua. Por eso, los agricultores que deseen seguir cultivando maíz en España, además de ser capaces de mejorar su rendimiento y reducir el impacto ambiental, deberán, sobre todo, mejorar sus márgenes de beneficio

Predicting N Status in Maize with Clip Sensors: Choosing Sensor, Leaf Sampling Point, and Timing

Nitrogen (N) losses from agricultural systems increase air and water pollution, and these losses are highly correlated with the excessive fertilization. An adjusted N fertilization is then a key factor in increasing the N fertilizer efficiency, and leaf clip sensors can help to improve it. This study (combining five different field experiments in Central Spain) tried to identify the ability of the clip sensors in maize N status identification and yield prediction, comparing two different devices (SPAD-502® and Dualex®) and identifying the best protocol for maize leaf sampling. As a result, the study demonstrated that different leaf clip chlorophyll sensors presented similar results, although some differences appeared at larger N concentrations. Complementary polyphenol information (as flavonol) can improve the maize N deficiency prediction. Moreover, valuable information for a proper sampling protocol was obtained with this study. It proved that the sampling position (in the leaf and in the plant) and sampling time were crucial for a better estimation of the maize N status. Proper fertilization recommendations could be achieved based on clip chlorophyll sensor measurements

LONG term management systems under semiarid conditions Influence on labile organic matter, β-glucosidase activity and microbial efficiency

Conservation agriculture (CA) practices have been widely applied on a variety of agro-ecosystems in order to prevent soil degradation and to improve fertility. We studied the long term influence of different management systems on soil properties in an experimental field located in semiarid central Spain. Soil organic carbon (SOC), dissolved organic carbon (DOC), soil basal respiration (CO2-C), microbial biomass carbon (MBC) and β-glucosidase activity have been measured during three cropping seasons. Results showed a high influence of date of sampling on the evaluated parameters and on the microbial status and activity, most likely due to variations in soil water content (SWC). Microbial efficiency and β-glucosidase activity were improved under CA, as SOC, DOC and MBC were accumulated in the surface. Microbial efficiency ratios, e.g.;qR (qR=MBC/SOC), qCO2 (qCO2=CO2-C /MBC) and qCO2/SOC, were useful to explain the influence of sampling date and the management practices on the microbial status. A stepwise procedure reduced considerably our data set, allowing the selection of MBC, DOC and qCO2/SOC as reliable indicators to evaluate soil quality in semiarid areas. © 2015 Elsevier B.V