RESUMO
The use of grasses as cover crops in the off-season of cash crops under no-till has been largely adopted. However, soil phosphorus (P) uptake was previously shown to be reduced when ruzigrass is introduced in the rotation, affecting the viability and sustainability of this cropping system. The objective of this study was to assess the effect of ruzigrass on soil P availability and desorption kinetics under different P fertilizer application rates. A long-term field experiment where soybean (Glycine max) has been grown in rotation with ruzigrass (Urochloa ruziziensis) or fallow for 10â¯years, with the application of 0, 13, and 26â¯kgâ¯ha-1 of P, was evaluated for two consecutive years. Soil P desorption kinetics was assessed using diffusive equilibrium (DET) and gradient in thin films (DGT) techniques, as well as the DGT-induced fluxes in soils model (DIFS). Microbial biomass P (MBP) was assessed to verify if soil solution P (PDET) was reduced due to immobilization by microorganisms. Ruzigrass reduced MBP and PDET especially when P fertilizer was applied. The concentration of labile P (PDGT) was also lower after ruzigrass than in fallow. The soil ability to resupply P to soil solution was lower after ruzigrass regardless of P rates due to a slower desorption in response to the perturbation imposed by DGT. Growing ruzigrass as cover crop in the soybean off-season decreases soil P availability regardless of P fertilizer application rates by fundamentally reducing P mobility and P resupply from soil solid phase into soil solution.
RESUMO
Climate change is likely to affect the nature of pathogens/ chemicals in the environment and their fate and transport. We assess the implications of climate change for changes in human exposures to pathogens/chemicals in agricultural systems in the UK and discuss the effects on health impacts, using expert input and literature on climate change; health effects from exposure to pathogens/chemicals arising from agriculture; inputs of chemicals/pathogens to agricultural systems; and human exposure pathways for pathogens/chemicals in agricultural systems. We established the evidence base for health effects of chemicals/pathogens in the agricultural environment; determined the potential implications of climate change on chemical/pathogen inputs in agricultural systems; and explored the effects of climate change on environmental transport and fate of various contaminants. We merged data to assess the implications of climate change in terms of indirect human exposure to pathogens/chemicals in agricultural systems, and defined recommendations on future research and policy changes to manage adverse increases in risks.
Assuntos
Agricultura , Microbiologia do Ar , Mudança Climática , Exposição Ambiental/efeitos adversos , Poluição Ambiental/efeitos adversos , Microbiologia da Água , Humanos , Reino UnidoRESUMO
Climate change is likely to affect the nature of pathogens/ chemicals in the environment and their fate and transport. We assess the implications of climate change for changes in human exposures to pathogens/chemicals in agricultural systems in the UK and discuss the effects on health impacts, using expert input and literature on climate change; health effects from exposure to pathogens/chemicals arising from agriculture; inputs of chemicals/pathogens to agricultural systems; and human exposure pathways for pathogens/chemicals in agricultural systems. We established the evidence base for health effects of chemicals/pathogens in the agricultural environment; determined the potential implications of climate change on chemical/pathogen inputs in agricultural systems; and explored the effects of climate change on environmental transport and fate of various contaminants. We merged data to assess the implications of climate change in terms of indirect human exposure to pathogens/chemicals in agricultural systems, and defined recommendations on future research and policy changes to manage adverse increases in risks.
É provável que a mudança climática afete a natureza, destino e transporte de elementos patogênicos/químicos no ambiente . Avaliamos as implicações das mudanças climáticas em mudanças na exposição humana a elementos patogênicos/químicos nos sistemas agrícolas no Reino Unido e discutimos os efeitos sobre os impactos à saúde, usando a contribuição de especialistas e literatura; efeitos à saúde da exposição a elementos patogênicos/químicos provenientes da agricultura; introdução de elementos químicos/patogênicos e caminhos de exposição humana a elementos patogênicos/químicos nos sistemas agrícolas. Definimos a base de evidência para efeitos de saúde de elementos químicos/patogênicos no ambiente agrícola; determinamos as possíveis implicações da mudança climática na introdução de elementos químicos/patogênicos nos sistemas agrícolas; e exploramos os efeitos da mudança climática no transporte ambiental e destino de diversos contaminantes. Consolidamos dados para avaliar as implicações das mudanças climáticas em relação à exposição humana indireta a elementos patogênicos/químicos nos sistemas agrícolas e recomendamos futuras pesquisas e mudanças políticas para administrar aumentos adversos nos riscos.