Suitability of phytoliths as a quantitative process tracer for soil erosion studies

Phytoliths are plant microfossils commonly used as qualitative archive markers in archaeological and paleoecological studies. Their potential uniqueness to the vegetation cover, robustness to weathering, and lack of chemical alteration along the transport paths make them potentially suitable tracers for quantitative erosion studies. In this pilot study, we explore the potential of phytoliths in a sediment fingerprinting study in the Ceguera catchment (28 km2) in NE Spain. The phytolith concentrations and morphologies of four land cover classes (agricultural land, badland, forest, and shrubland) were analysed, and their contributions to four natural sediment mixture samples along the river course were modelled. Phytolith concentrations allowed us to discriminate sources sufficiently, albeit with limited sample size. The performance of the phytoliths as tracer was tested by reproducing the sources of artificial sediment mixture samples with satisfactory recall ratio. Results identified badlands to be the main contributor, with 84–96% of the sediment load to the sinks, followed by shrublands (median 5%) and agricultural lands (median 2%). These major findings can be reproduced by other conventional erosion studies from this area, indicating that phytoliths are suited to quantifying erosion patterns in mesoscale catchments

The complete incremental cost test for cross-subsidies with a sub-modular cost function

Incremental cost, Stand-alone cost, Cross-subsidy, Sub-modular, D24, L11, L13, L51, L59,

Sugarcane phytoliths: encapsulation and sequestration of a long-lived carbon fraction

The potential to reduce emissions from agriculture and increase the amount of carbon captured in soils is currently being examined by researchers in a number of countries. This paper describes a process of carbon capture and long-term storage using silica phytoliths and, provides the results of a study of this process on newly planted and ratooned sugarcane varieties. Our results indicate that a) there was significant variation in the phytolith occluded carbon (PhytOC) content of different varieties, b) this did not appear to be directly related to the quantity of silica in the plant but rather the efficiency of carbon encapsulation by individual varieties and c) it was possible to accurately quantify this carbon fraction prior to its incorporation into soil. The carbon content of the varieties tested under the particular suite of environmental conditions for which they were grown ranged from 0.12 te-CO2 ha-y−1 to 0.36 te-CO2 ha-y−1. This PhytOC process provides an approach which reduces emissions from agriculture for the long-term (millennia), as opposed to many other soil organic carbon fractions that may decompose over a much shorter time. Moreover, the ability to quantify PhytOC prior to its incorporation into the soil will provide a distinct practical advantage for the quantification of this carbon form over other soil carbon fractions in emerging emissions trading and offset markets