New Forests - Native trees from the Caribbean were tested for seed desiccation responses, by adapting the “100-seed test” protocol. Ninety-seven seed lots of 91 species were collected... 相似文献
The main objective of this study was to analyse how different sewage sludges influence soil wetting and drying dynamics. Three composted and three thermally‐dried municipal sludges from different wastewater plants located in Catalonia (NE Spain) were mixed with a mine‐soil obtained from a limestone quarry. Measurements of the time required to reach zero contact angle () and water holding time (WHT) provided information on the time required for a mine‐soil to reach its complete wettability and the residence time of water stored between ?0.75 and ?25 MPa of soil suction, respectively. One month after sludge amendments, one composted and one thermally‐dried sludge significantly increased . WHT was increased in the mine‐soil treated by composted sludges (50.6% by Blanes' sludge, 65.5% by Manresa's sludge and 52.5% by Vilaseca's sludge) one month after sludge amendments. The amount of water retained in the mine‐soil was increased by all composted sludges and one thermally‐dried sludge after one month (by 42.3% with Blanes' sludge, 42.3% with Manresa's sludge, 65.7% with Vilaseca's sludge and 23.9% with Mataró's sludge) and one year after sludge amendments and at a small suction. Increments in WHT corresponded with the amount of water retained so the time‐scale of soil water availability should also be considered. The value was modified mainly by increments in carbon stock and microbial biomass, while the WHT was modified mainly by increments in pH and electrical conductivity. Under similar air‐drying conditions, mine‐soil treated with composted sludges retained more water for longer compared with thermally‐dried sludges. 相似文献
The environmental benefits of biochar application, ranging from improvements in crop yield to global change mitigation, have been extensively studied in the last decade. However, such benefits have not been profusely demonstrated under a Mediterranean climate and still less in combination with high pH soils. In our study, the short to medium effects of biochar application on a soil-plant system under Mediterranean conditions in an alkaline soil were assessed.
Material and methods
Barley plants were grown in field mesocosms during three agronomical years at three biochar addition rates (0, 5, and 30 t ha?1). Related to soil, different physicochemical parameters were analyzed as well as microbial respiration, biomass, and functional diversity. In the plant domain, in vivo ecophysiology variables such as leaf transpiration rate, stomatal conductance, and photosynthesis rate were determined while photosynthetic pigment content and soluble protein concentrations were measured in the laboratory. Additionally, crop yield and nutrient composition were also analyzed. The soil-plant connection was investigated by the N content ratio in both fractions establishing the nitrogen efficiency in the system.
Results and discussion
The highest rate of biochar amendment enhanced soil moisture and electrical conductivity combined with an increase of SO42?, Cl?, Mg2+, and K+, and decrease of NO3? and HPO4?. Notable variations regarding nutrition and moisture were induced in this Mediterranean alkaline soil after biochar addition although pH remained stable. Contrastingly, there were no major effects on microbial activity, but a lower abundance of the nosZ functional gene was found. Similarly, plant parameters were unaffected regarding chemical composition and ecophysiology although biochar induced a higher efficiency in the plant nitrogen uptake without increasing crop yield.
Conclusions
Biochar addition at the highest rate (30 t ha?1) reduced soil-soluble nitrate although N uptake by the plant remained invariable, in turn coupled to no effects on crop productivity. Our study showed that, in a Mediterranean agroecosystem, a wood biochar produced by gasification was unable to increase crop yield, but enhanced soil water retention, decreased the need for N fertilization, and decreased soil-soluble nitrate concentrations, something that could help to mitigate the excessive nitrate levels associated with over-fertilization.
Biochar is a carbon-rich product, able to enhance soil fertility and mitigate CO2 emissions. While biochar effects on agriculture are becoming known, its impact elsewhere, e.g., on estuarine ecosystems, has yet to be assessed. The main aim of the present study was to determine the effect of biochar on sediment–water retention, CO2 emissions from sedimentary organic carbon decomposition, sediment pH and electrical conductivity, in aerobic conditions similar to those observed at low tide.
Materials and methods
Sediments from the Mondego Estuary (Portugal) were mixed with pine gasification biochar at different doses (5, 10, 14 %) and immersed in water with different salinity values (15, 25, 30) for 96 h. The influence of biochar on water retention, the residence time of water and CO2 emissions between ?0.75 and ?1.5 MPa, total organic carbon, pH and electrical conductivity (EC) were determined. Carbon chemical composition and polycyclic aromatic hydrocarbon (PAH) concentrations were determined in sediments and biochar. Differences between biochar treatments after immersion in different water salinities were analysed using the Kruskal–Wallis test.
Results and discussion
Results showed that biochar was able to (a) increase sediment–water content in terms of quantity and residence time, (b) decrease CO2 emissions, but only with a specific soil–water content and at the highest biochar dose, (c) increase sediment pH at all biochar doses and (d) increase sediment EC at the highest biochar dose. In contrast, the percentage of carbon mineralised was not modified. Biochar carbon was rich in PAHs and less decomposable than sedimentary carbon. The increments observed in sediment pH and EC were unable to change sediment alkaline or saline status according to standard classifications.
Conclusions
Our results suggest that the remarkable water adsorption capacity of biochar–sediment mixtures may be considered the main factor in regulating CO2 emission rates from sediments, together with high PAH concentrations, which probably restrain the organic matter decomposition process.
Mining activities disturb land and reduce its capacity to support a complete functional ecosystem. Reclamation activities
in this case are not easy due to the large amount of soil required. This is why mining debris are usually used as surrogate
of soil, despite their unsuitable physicochemical properties. However, these properties can be improved with the amendment
using an organic source, usually sewage sludge. Nevertheless, the use of sludge might lead to impacts on soil and water ecosystems
because of its physicochemical properties and pollutant content. The aim of this study is to assess the suitability of the
use of mining debris amended with sewage sludge as practice for the reclamation of land degraded by limestone-quarrying activities. 相似文献
The efficient storage and germination of seeds underpin the effective use of plants for livelihoods and sustainable development. A total of 204 wild species useful for local communities of the Tehuacán–Cuicatlán Valley were collected and stored in seed banks in country for long term conservation, and 66 % (i.e., 134) duplicated in the U.K., as an effective means of ex situ conservation. Of the 204 species, 147 (122 of which also duplicated in the U.K.) were previously listed as useful plants in the ethnofloristic inventory of the Valley. Based on literature surveys, we found that one of the major impediments to the use of stored seeds of wild species is the lack of knowledge of how to germinate the seed. In detailed studies, we found that seeds of 18 useful plant species from 10 different families germinated readily and could be propagated. In contrast, four species (Actinocheita filicina, Bursera submoniliformis, Karwinskia mollis and Lippia graveolens) produced dormant seeds and therefore further studies are needed before their use can be maximised in large scale propagation programmes in support of conservation and livelihoods. Overall, this large-scale study on useful wild plant species in Mexico confirms that conventional seed banking can effectively support sustainable development and livelihood programmes. 相似文献
