Tillage effects on weed seed bank with wheat monoculture and rotational

El banco de semillas de malas hierbas presente en el suelo es una demostración de la existencia de una comunidad de malas hierbas y está vinculado a las fases de crecimiento de un ecosistema. Las prácticas agronómicas pueden ocasionar cambios en el banco de semillas de los suelos agrícolas. Nuestro objetivo fue comparar la influencia del laboreo de conservación (mínimo laboreo y siembra directa) frente al laboreo convencional, sobre la densidad y riqueza específica del banco de semillas persistente de un suelo agrícola, en parcelas con dos sistemas de cultivo: monocultivo y rotación de trigo de invierno. Se tomaron muestras de suelo en parcelas con los tres sistemas de laboreo, a 3 profundidades: 0-7 cm, 7-15 cm y 15-30 cm. Los resultados obtenidos en este estudio mostraron que el efecto acumulativo del laboreo en parcelas con trigo en monocultivo no tuvo efectos en la densidad de semillas, aunque sí en su distribución, cuantificadas mayoritariamente a mayor profundidad (P3). Por otro lado, se observó una clara influencia del laboreo y la profundidad en la densidad y riqueza específica del banco de semillas de tipo persistente del suelo, en las parcelas con rotación de trigo. Nuestros resultados confirman que una variedad de cultivos puede ir asociada a una mayor variedad de especies de malas hierbas presentes en el banco de semillas del suelo.The weed seedbank into the soil is a demonstration of the existence of a weed community and it is linked to ecosystem growth phases. Agronomic practices can cause changes in the seed bank of agricultural soils. Our objective was to compare the influence of conservation tillage (mínimum tillage and direct seeding) with conventional tillage on weed seed density and species richness of persistent seedbank, with two cropping systems: wheat monoculture and wheat rotation. Soil samples were taken in plots with three tillage systems, at 3 depths: P1 (0-7 cm), P2 (7-15cm) and P3 (15-30 cm). The results of this study showed that cumulative effects of tillage systems, in wheat monoculture plots, had no effect on seed density, and the seed species were concentrated in deepest section of soil (P3). On the other hand, we observed a clear influence of tillage and depth on weed density and species richness of the persistent weed seed bank in wheat rotation plots. Our results confirm that a variety of crops could be associated to a variety of weed species present into soil seedbank

The competitive ability of weed communities in selected crucifer oilseed crops under different water and nitrogen

Durante los años 2012 y 2013, se llevó a cabo un experimento en el centro de la península cuyo objetivo fue el estudio de la flora arvense en 3 especies de “Brassica” (“B. carinata”, “B. juncea” y “B. nigra”). Las malas hierbas se evaluaron con 2 niveles de riego, con y sin aporte de agua, y con tres dosis de fertilización diferentes: 0, 75 y 150 kg N ha-1. El establecimiento del cultivo de las tres especies de “Brassica” varió en función del año. Las escasas lluvias de 2012 redujeron la densidad y biomasa de la flora arvense en comparación con el año 2013 en el que la pluviometría fue mayor. Los resultados sugieren que la especie “B. nigra” no estaba bien adaptada a nuestras condiciones climáticas continentales, mostrando un rendimiento más bajo que el resto de los cultivares. Por otro lado, la infestación de malas hierbas fue menor en todas las parcelas donde se cultivaba “B. carinata”.A field study was undertaken to examine the interaction and relationships between weeds and three “Brassica” species (“B. carinata”, “B. juncea” and “B. nigra”) grown in 2012 and 2013. We evaluated the weed density, fresh and dry biomass of weeds with 2 water regimes: with and without irrigation, and three different doses of fertilization: 0, 75 and 150 kg N ha-1. Crop establishment of “Brassica” species varied significantly each year. Lower rainfall in 2012 led to lower density, fresh and dry biomass of weeds compared to 2013. The results confirmed that “B. nigra” was not well adapted to our continental climatic conditions, and thus the yield was lower than the other cultivars. The lowest weed infestation occurred in plots where “B. carinata” was grown in all cases

Weed control options in conventional and GM maize

En el proyecto AMIGA, que estudia los posibles efectos de los cultivos modificados genéticamente y su manejo sobre el agro-eco-sistema y la biodiversidad, se han evaluado varios tratamientos herbicidas sobre maíz Bt y maíz convencional. Se estableció un ensayo de seis hectáreas durante dos años en el que se han utilizado cinco manejos con herbicida que incluyen tratamiento convencional, reducido, glifosato y dos combinaciones de los anteriores. Se muestreó a lo largo del desarrollo del cultivo para determinar las especies de malas hierbas y artrópodos en el tiempo así como su abundancia y diversidad mediante examen visual y uso de trampas de gravedad y adhesivas amarillas. En este trabajo se presentan datos de abundancia de malas hierbas a madurez fisiológica del cultivo y del total de artrópodos en muestreo visual.Effect on weeds and arthropods In the context of AMIGA project which studies the posible effects of genetically modified crops and their management on the agro-ecosystem and biodiversity, we have studied various herbicide treatments applied on conventional and Bt A field was conducted for two years in a six ha plot. Five herbicide treatments including conventional, reduced, glyphosate and two herbicides combinations were established. We sampled along the cropping period to determine the species of weeds and arthropods over time and their abundance and diversity. The presence of arthropods was determined by visual examination and the use of pitfall and yellow sticky traps. In this work whole abundance of weeds at physiological maturity of the crop and total abundance of arthropod in visual examination are presented

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

Effects of tillage, crop systems and fertilization on weed abundance and diversity in 4-year dry land winter wheat

The arable fields in central Spain have been dominated by cereal production, especially winter wheat. In this area, the defined action of weed management program requires a clear understanding of the factors and mechanisms conditioning weed community dynamics in agro systems. This study evaluated the effects of different agricultural management systems on the abundance and diversity of weed communities in winter wheat crops.Weed density and composition of weed species were sampled over four years; comparing monoculture wheat and rotational wheat in three agricultural management systems (1) direct drilling (no-tillage, NT); (2) chisel ploughing (minimum tillage 15. cm depth, MT) and (3) mouldboard ploughing (traditional tillage 20. cm depth, CT). With the aim to be able to improve weed management in agro systems with semiarid environments; within each of the agricultural management systems, we examined the impact of mineral fertilization (traditional and balanced) as a tool for reducing the external inputs in arable cereals.Weed diversity was assessed using the three common diversity indices Shannon's index, evenness index and species richness. The data collected showed total weed density was different per tillage system and each year of the study, but we did not find significant differences between crop systems over the study.The abundance, diversity and evenness of the weed community in the arable field, were significantly increased in NT systems. Within the direct drilling (NT) plots, rotational wheat showed the highest levels of weed infestation and diversity. Comparing traditional and balanced mineral fertilization of soil did not reveal a significant effect on weed abundance and diversity observed in field. © 2013 Elsevier B.V

Estudio fitotóxico de los isómeros "E/Z" del herbicida alloxidim en trigo

Alloxydim is an herbicide marketed as the E-isomer applied at early stages of grass weeds. In the field, sunlight and temperature can induce the isomerization reaction of E-alloxydim to form the mixture of E and Z isomers. A bioassay has been performed to compare the herbicidal activity of E-alloxydim and its corresponding E/Z isomeric mixture in wheat plants. The IC50 values calculated from the root lengths of wheat for E-alloxydim and alloxydim mixture were 0.37 and 0.70 mg L-1, respectively. The Z isomer of alloxydim in the isomeric mixture has no phytotoxic effect on the wheat germination whereas E-alloxydim inhibited the seed germination at low concentrations (from 0.0 to 4.0 mg L-1).Aloxidim es un herbicida comercializado como el isómero E que se aplica en los estadios tempranos de las malas hierbas. En el campo, la luz solar y la temperatura pueden inducir las reacción de isomerización de E-aloxidim para formar la mezcla de los isómeros E y Z. Se ha llevado a cabo un bioensayo para comparar la actividad herbicida de E-aloxydim y su correspondiente mezcla de isómeros E/Z en trigo. Los valores de IC50 calculados a partir de la longitud de raíz de trigo de E-aloxidim y la mezcla 0,37 y 0,70 mg L-1, respectivamente. El isómero Z-aloxidim en la mezcla isomérica no tiene efecto fitotóxico sobre la germinación de trigo, mientras que E- aloxidim inhibe la germinación de semillas a bajas concentraciones (de 0,0 a 4,0 mg L-1)

The influence of soil tillage system on Salsola kali

10 Pág.With the move towards conservation agriculture, we have seen an increase in weeds such as Salsola kali L., well known as Russian thistle, which are wind spread over fallow land. The emergence of this weed species seemed erratic, perhaps connected to climate conditions and management techniques. In order to shed some light on this issue, we carried out a field experiment over 3 years to monitor Russian thistle density in fallow plots, comparing three tillage systems. This study provides an insight about the limitations of assuming no-tillage techniques within a cropping system that include fallow in the rotation sequence. Our results show that no-tillage systems are more vulnerable to S. kali. Low spring rain leads to high S. kali density, especially in no-tillage plots. High spring rainfall reduced the emergence in all tillage systems because of soil water saturation. Minimum tillage technique served to maintain control over this species even in weather conditions that favoured its emergence in other systems. In order to reduce the need for herbicide in fallow lands under conservation systems, we recommend the implementation of minimum tillage to combat Russian thistle infestation.This work has been funded by Projects AT2017‐003, RTA 2017‐00006‐C03‐01 (Spanish Ministry of Science and Innovation) and Comunidad de Madrid (Spain) and Structural Funds 2014‐2020 (ERDF and ESF) for the financial support (project AGRISOST‐CM S2018/BAA‐4330). We are grateful to D. San Martín and J. Silveria for their helping managing the experiment. We are grateful to Charlotte Harvey for English editing.Peer reviewe