Edaphic controls on ecosystem-level carbon allocation in two contrasting Amazon forests

Three components of carbon allocation, biomass, flux, and partitioning, were measured in two contrasting Amazon forests growing under similar climatic conditions. Allocation to aboveground compartments was highest in a high-stature forest growing on clay soils, while allocation to fine roots was higher in a short-stature forest growing on white sands. Differences in carbon allocation components where not proportional between the two forests, with soils controlling a trade-off between allocation to fine roots versus aboveground parts.

Risk of Leaching in Soils Amended by Compost and digestate from Municipal Solid Waste

New European directives have proposed the direct application of compost and digestate produced from municipal solid wastes as organic matter sources in agricultural soils. Therefore information about phosphorus leaching from these residues when they are applied to the soil is increasingly mportant. Leaching experiments were conducted to determine the P mobility in compost and digestate mixtures, supplying equivalent amounts to 100 kg P ha?1 to three different types of soils. The tests were performed in accordance with CEN/TS 14405:2004 analyzing the maximum dissolved reactive P and the kinetic rate in the leachate. P biowaste fractionation indicated that digestate has a higher level of available P than compost has. In contrast, P losses in leaching experiments with soil-compost mixtureswere higher than in soil-digestate mixtures. For bothwastes, therewas no correlation between disolved reactive P lost and the water soluble P.The interaction between soil and waste, the long experimentation time, and the volume of leachate obtained caused the waste?s wettability to become an influential parameter in P leaching behavior. The overall conclusion is that kinetic data analysis provides valuable information concerning the sorption mechanism that can be used for predicting the large-scale behavior of soil systems.

Modeling GHG emissions, N and C dynamics in Spanish agricultural soils.

To date, only few initiatives have been carried out in Spain in order to use mathematical models (e.g. DNDC, DayCent, FASSET y SIMSNIC) to estimate nitrogen (N) and carbon (C) dynamics as well as greenhouse gases (GHG) in Spanish agrosystems. Modeling at this level may allow to gain insight on both the complex relationships between biological and physicochemical processes, controlling the processes leading to GHG production and consumption in soils (e.g. nitrification, denitrification, decomposing, etc.), and the interactions between C and N cycles within the different components of the continuum plant-soil-environment. Additionally, these models can simulate the processes behind production, consumition and transport of GHG (e.g. nitrous oxide, N2O, and carbon dioxide, CO2) in the short and medium term and at different scales. Other sources of potential pollution from soils can be identified and quantified using these process-based models (e.g. NO3 y NH3).

Arsenic, antimony and selenium in urban soils: potential risks for human health in urban gardening

The benefits of urban agriculture are many and well documented, ranging from health improvement to community betterment, more sustainable urban development and environment protection. On the negative side, urban soils are commonly enriched in toxic trace elements that have accumulated over time through the deposition of atmospheric particles (generated by automotive traffic, heating systems, historical industrial activities and resuspended street dust), and the uncontrolled disposal of domestic, commercial and industrial wastes. This in turn has given rise to concerns about the level of exposure of urban farmers to these elements and the potential health hazards associated with this exposure. Research efforts in this field have started relatively recently and have almost systematically omitted the influence of Sb and Se, and to a lesser extent of As, although all three have proven toxic effects.