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

Crop rotational diversity can mitigate climate-induced grain yield losses

Diversified crop rotations have been suggested to reduce grain yield losses from the adverse climatic conditions increasingly common under climate change. Nevertheless, the potential for climate change adaptation of different crop rotational diversity (CRD) remains undetermined. We quantified how climatic conditions affect small grain and maize yields under different CRDs in 32 long-term (10-63 years) field experiments across Europe and North America. Species-diverse and functionally rich rotations more than compensated yield losses from anomalous warm conditions, long and warm dry spells, as well as from anomalous wet (for small grains) or dry (for maize) conditions. Adding a single functional group or crop species to monocultures counteracted yield losses from substantial changes in climatic conditions. The benefits of a further increase in CRD are comparable with those of improved climatic conditions. For instance, the maize yield benefits of adding three crop species to monocultures under detrimental climatic conditions exceeded the average yield of monocultures by up to 553 kg/ha under non-detrimental climatic conditions. Increased crop functional richness improved yields under high temperature, irrespective of precipitation. Conversely, yield benefits peaked at between two and four crop species in the rotation, depending on climatic conditions and crop, and declined at higher species diversity. Thus, crop species diversity could be adjusted to maximize yield benefits. Diversifying rotations with functionally distinct crops is an adaptation of cropping systems to global warming and changes in precipitation.</p

Increasing crop rotational diversity can enhance cereal yields

Diversifying agriculture by rotating a greater number of crop species in sequence is a promising practice to reduce negative impacts of crop production on the environment and maintain yields. However, it is unclear to what extent cereal yields change with crop rotation diversity and external nitrogen fertilization level over time, and which functional groups of crops provide the most yield benefit. Here, using grain yield data of small grain cereals and maize from 32 long-term (10–63 years) experiments across Europe and North America, we show that crop rotational diversity, measured as crop species diversity and functional richness, enhanced grain yields. This yield benefit increased over time. Only the yields of winter-sown small grain cereals showed a decline at the highest level of species diversity. Diversification was beneficial to all cereals with a low external nitrogen input, particularly maize, enabling a lower dependence on nitrogen fertilisers and ultimately reducing greenhouse gas emissions and nitrogen pollution. The results suggest that increasing crop functional richness rather than species diversity can be a strategy for supporting grain yields across many environments

Increasing crop rotational diversity can enhance cereal yields

9 Pág.Diversifying agriculture by rotating a greater number of crop species in sequence is a promising practice to reduce negative impacts of crop production on the environment and maintain yields. However, it is unclear to what extent cereal yields change with crop rotation diversity and external nitrogen fertilization level over time, and which functional groups of crops provide the most yield benefit. Here, using grain yield data of small grain cereals and maize from 32 long-term (10–63 years) experiments across Europe and North America, we show that crop rotational diversity, measured as crop species diversity and functional richness, enhanced grain yields. This yield benefit increased over time. Only the yields of winter-sown small grain cereals showed a decline at the highest level of species diversity. Diversification was beneficial to all cereals with a low external nitrogen input, particularly maize, enabling a lower dependence on nitrogen fertilisers and ultimately reducing greenhouse gas emissions and nitrogen pollution. The results suggest that increasing crop functional richness rather than species diversity can be a strategy for supporting grain yields across many environments.G.V., R.B. and S.H. acknowledge FORMAS grants 2018-02872 and 2018-02321. TMB acknowledges USDA AFRI grant 2017-67013-26254. LTEs managed by SRUC were supported by the Scottish Government RESAS Strategic Research Programme under project D3-, Healthy Soils for a Green Recovery. Swedish LTEs were funded by the Swedish University of Agricultural Sciences (SLU). We thank the Lawes Agricultural Trust and Rothamsted Research for data from the e-RA database. The Rothamsted Long-term Experiments National Capability (LTE-NC) was supported by the UK BBSRC (Biotechnology and Biological Sciences Research Council, BBS/E/C/000J0300) and the Lawes Agricultural Trust. The Woodslee site was supported by the Agro-Ecosystem Resilience Program (Agriculture & Agri-Food Canada) and field management provided by field crews over 6 decades is appreciated. La Canaleja LTE (Spain) was supported by RTA2017-00006-C03-01 project (Ministry of Science and Innovation. El Encín LTEs were supported by Spanish Ministry of Economy and Competitiveness funds (projects AGL2002-04186-C03-01.03, AGL2007-65698-C03-01.03, AGL2012-39929-C03-01 of which L. Navarrete was the P.I). R.A., A.G.D. and E.H.P. are also grateful to all members of the Weed Science Group from El Encín Experimental Station for their technical assistance in managing the experiments. The Brody/Poznan University of Life Sciences long-term experiments were funded by the Polish Ministry of Education and Science. We acknowledge the E-Obs dataset from the EU-FP6 project UERRA (http://www.uerra.eu) and the Copernicus Climate Change Service, and the data providers in the ECA&D project (https://www.ecad.eu/).Peer reviewe

Biomass production and nutrient concentration of kenaf grown on sewage sludge-amended soil

Due to increasingly strict control of wastewater treatment, the production of sewage sludge is surging and the problem of its disposal is therefore also growing. Recycling this waste as a fertilizer is an economically and environmentally attractive option. Determining the availability of macro- and micronutrients in these sludges is important if such wastes are to provide sufficient nutrients to crops while causing minimal environmental damage. A greenhouse study with two kenaf cultivars (�Everglades 41� and �Tainung 2�) was designed to evaluate the effects of sewage sludge processing mode on plant development, biomass yield, and nutrient availability. Two different processing modes of sludges (digested dewatered and pelletized-heat dried) applied at two rates, 10 and 20 Mg ha�1 were compared with inorganic N and a zero-N control. Plant height, basal stems diameter and biomass production increased slightly with the sewage sludge treatments but in different manners depending on the kenaf cultivar in question. Both sludges were similar in their ability to supply N to the plants. Apparent N recovery and N fertilizer equivalent value were greater in the low dosage treatments. Of the two cultivars, �Everglades 41� showed greater mean values for all the variables studied. No differences were found in leaf P, K, Ca, Mg contents among treatments. The Zn and Cu concentrations were the only trace elements that increased in the leaf tissues with sludge application, although the values recorded were well below critical environmental thresholds.La eliminación de los lodos de depuradora supone un gran problema, debido al estricto control de los tratamientos de aguas residuales. El reciclado como fertilizante es una opción muy atractiva tanto económica como medioambiental. Es importante evaluar la capacidad de estos residuos para aportar nutrientes en dosis suficientes a los cultivos sin causar daños medioambientales. Se diseñó un estudio en invernadero con dos cultivares de kenaf (�Everglades 41� y �Tainung 2�) para evaluar los efectos de dos técnicas diferentes en el proceso de secado de lodos (deshidratado por centrifuga y secado térmico-pelletizado) sobre el desarrollo de la planta, la producción de biomasa y la disponibilidad de nutrientes. Se aplicaron dos dosis de lodos (10 y 20 Mg ha�1), que fueron comparadas con un aporte de N inorgánico y con un control sin fertilizar. Los tratamientos con lodos aumentaron ligeramente la altura de la planta, el diámetro del tallo y la producción de biomasa, pero de forma diferente según el cultivar. La capacidad de aportar N a las plantas fue similar en los dos tipos de lodos. Los valores de recuperación aparente de N y de equivalentes de fertilizante nitrogenado fueron mayores en las dosis más bajas de los lodos. Los valores de todas las variables estudiadas fueron mayores en �Everglades 41�. No hubo diferencias entre tratamientos en el contenido foliar de P, K, Ca y Mg. Los tratamientos con lodos sólo aumentaron los contenidos foliares de Zn y Cu, de todos los elementos traza estudiados, pero por debajo de los umbrales críticos

Influence of tillage practices on soil biologically active organic matter content over a growing season under semiarid Mediterranean climate

In semiarid areas, traditional, intensive tillage has led to the depletion of soil organic matter, which has resulted in reduced soil fertility. The aim of the present work was to evaluate the effects of different soil management systems, practised over 12 years, on soil organic carbon (SOC), nitrogen (SN) and biologically active organic matter [particulate organic matter (POM); potentially mineralisable nitrogen (PMN); microbial biomass (MB)]. A Mediterranean Alfisol, located in central Spain, was managed using combinations of conventional tillage (CT), minimum tillage (MT) or notillage (NT), plus a cropping background of either continuous wheat (WW) or a fallow/wheat/pea/barley rotation (FW). Soil was sampled at two depths on four occasions during 2006-2007. The results showed the sampling date and the cropping background to significantly affect the SOC (p < 0.0057 and p < 0.0001 respectively). Tillage practice, however, had no effect on SOC or SN. The C-and N-POM contents were significantly influenced by the date, tillage and rotation. These variables were significantly higher under NT than CT and under WW than FW. The PMN was influenced by date, tillage and rotation, while C-MB was significantly affected by tillage (p < 0.0063), but not by rotation. The NT plots accumulated 66% C-POM, 60% N-POM, 39% PMN and 84% C-MB more than the CT plots. After more than 12 years, the benefits of conservation practices were found in the considered soil properties, mainly under no tillage. In order to obtain a consistent data set to predict soil biological status, it is necessary further study over time