Marks E.A.N., Mattana S., Alcañiz J.M., Pérez-Herrero E., Domene X. (2016) Gasifier biochar effects on nutrient availability, organic matter mineralization, and soil fauna activity in a multi-year Mediterranean trial. Agriculture, Ecosystems and Environment. 215: 30-39.LinkDoi: 10.1016/j.agee.2015.09.004
Gasifier pine biochar is a carbon-rich material which may be useful as a soil amendment. In Europe and elsewhere there may be potential added value of char produced in industrial gasifiers, up to now considered as wastes. Pine gasification biochar was tested as a soil amendment in a multi-year Mediterranean barley crop field trial, applied at 12 and 50tha-1 while applying half the usual N rate at 50kgha-1, contrasted with a full 100kg ha-1 N fertilizer treatment without biochar. Over the 6-30 month period following the application, biochar treatments did not have any significant effect on soil microbial biomass, respiration, or metabolic coefficient. N mineralization as NO3 - was decreased by biochar at 6 and 12 months from experiment start and coincided with ammonium accumulation. Biochar increased overall soil concentrations of K+ and SO4 2-, attributed to a direct additive effect, agreeing with data from other sources. Biochar treatments (with half usual N fertilization) did not have any significant effects on barley crop parameters, and when biochar treatments were contrasted against full N fertilization with no biochar, the usual N dosage was clearly more beneficial to crop development. Finally, soil fauna activity was negatively impacted by gasifier biochar treatments in years two and three, indicating a risk to soil processes mediated by soil invertebrates. Though this gasifier biochar is expected to be highly stable and therefore of interest for carbon sequestration, its utilization therefore risks negative effects on some biologically-mediated soil processes at high application rates. © 2015 Elsevier B.V.
Ojeda G., Mattana S., Avila A., Alcaniz J.M., Volkmann M., Bachmann J. (2015) Are soil-water functions affected by biochar application?. Geoderma. 249-250: 1-11.LinkDoi: 10.1016/j.geoderma.2015.02.014
Today biochar is considered a stable-carbon source that is able to improve soil quality. However, although biochar effects on some soil properties are already becoming well known, its impact on complex soil hydrological functions has yet to be better assessed. The main objectives are: (a) to determine the impact of different biochar amendments on important physical and chemical soil properties and (b) to determine whether the origin (biomass or sewage sludge) and pyrolysis technique can change biochar properties and regulate biochar influence on important soil functions, i.e. nutrient release, water sorption, and carbon storage. Six types of biochar produced from different biomass sources (pine, poplar or sludge) and pyrolysis processes (slow, fast or gasification) were applied to a sandy-loam, low-organic-matter, calcareous soil (mean dose: 18. g/kg) and incubated in a greenhouse without seeding. Two sampling campaigns, one month and one year after biochar amendments, were performed. The overall impact of biochar, analysed by principal response curves (PRCs), indicated that it could improve or deteriorate soil hydrological properties at different intensities. Soil wettability was modified due to sludge biochar addition to soil by increased water penetration dynamics during the capillary rise process of about 18%. In contrast, water storage as a soil function during soil drying was not affected. Because no differences on aggregate stability were observed between treatments, increments on soil organic carbon could not be related to biochar physical protection caused by aggregate formation or by enhanced aggregate stability. As a result, carbon storage, considered as a soil function provided by biochar, was mainly related to its chemical stability. On the other hand, nutrient flux during soil slaking was improved, increasing nutrient release from soil to water. In terms of biochar properties, an increment of surface wettability of biochar during water drop penetration was observed after one year of its addition to soil, where the mean values of contact angle (CA) decreased 69.5%. This important result suggest that initial biochar hydrophobicity (CA. >. 90°) disappeared after 1. year. It was observed that PRC analysis was able to identify important key soil properties that should be monitored when biochar is used as soil amendment. We conclude that the impact of biochar on soil functions depends mainly on biochar feedstock rather than on the pyrolysis technique used during its production. In general, the performance of biochar obtained from sludge and vegetal biomass was markedly different. © 2015 Elsevier B.V.
Marks E.A.N., Mattana S., Alcaniz J.M., Domene X. (2014) Biochars provoke diverse soil mesofauna reproductive responses inlaboratory bioassays. European Journal of Soil Biology. 60: 104-111.LinkDoi: 10.1016/j.ejsobi.2013.12.002
Biochar application to soil has the potential to improve soil fertility under certain conditions. However, potential ecological effects remain largely unexplored and poorly understood, particularly those on soil biota. Six biochars were tested on two soil-dwelling invertebrates in short-term bioassays to determine effects on survival and reproduction. A pine wood gasification char increased collembolan adult mortality at high concentrations. Wood slow and fast pyrolysis biochars had a strong stimulatory effect on collembolan reproduction, but no strong effect on enchytraeids. A sewage sludge char was slightly stimulatory for both organisms, and a pine gasification char was inhibitory in both cases. Inhibitory effects were associated with biochars with high carbonate and Ca content and pH. In light of the high stimulation of collembolan reproduction, potential explanations such as soil microbial community shifts or gut symbiont use of biochar are suggested. © 2013 Elsevier Masson SAS.
Ojeda G., Mattana S., Alcañiz J.M., Marando G., Bonmatí M., Woche S.K., Bachmann J. (2010) Wetting process and soil water retention of a minesoil amended with composted and thermally dried sludges. Geoderma. 156: 399-409.LinkDoi: 10.1016/j.geoderma.2010.03.011
Composting or thermally-drying sludges are becoming commonly used in soil rehabilitation of degraded land. Sludge amendments increase soil organic matter, but can reduce soil wettability due to hydrophobic compounds. The main objective of this study is to analyse how composted and thermally dried sludges influence soil wettability and water retention properties of a minesoil obtained from limestone extraction during quarrying rehabilitation activities. Three composted (Blanes, Manresa and Vilaseca) and three thermally dried (Besós, Mataró and Sabadell) municipal sludges from different wastewater plants of medium-sized towns located in Catalonia (NE Spain) were mixed with a minesoil and filled into lysimeters The minesoil water retention curves and, the time required for their measurement were analyzed together with various soil key parameters. Throughout the wetting process, three characteristic points of the water retention curve were identified: (i) the air soil dryness point corresponding to a soil suction of - 25 MPa, (ii) the critical point where high suction regime changes to low suction regime, located around - 6 MPa and (iii) the wilting point, corresponding to a soil suction of - 1.5 MPa. One month after sludge amendments (S1), two composted sludges increased the vapour wetting time corresponding to wilting point (twp) of minesoil, while 1 year after sludge amendments (S2) two thermally dried sludges decreased twp. On the other hand, all composted sludges and one thermally dried sludge increased minesoil water retention corresponding to wilting point (wwp) at sampling one (S1), while at sampling two (S2) similar effects were observed except in one composted sludge treatment. Regarding to soil biophysical properties, the addition of composted and thermally dried sludges to minesoil increased total organic carbon, soil-water contact angle, microbial biomass, pH and electrical conductivity at both experimental time scales (S1 and S2), while extractable carbohydrates was only modified at S1. The sludge effects on soil wetting properties and biophysical parameters were dependent on sewage sludge origin and the type of post-treatment. Increases in total organic carbon, extractable carbohydrates, contact angle, microbial biomass or electrical conductivity and decreases in pH corresponded with increases in twp and wwp. It was observed that under similar conditions of water vapour adsorption, minesoil amended with composted sludge could have more difficulties to overcome the permanent wilting point under wetting process. © 2010 Elsevier B.V. All rights reserved.
Mattana S, Ortiz O, Alcañiz JM (2010) Substrate-Induced Respiration of a Sandy Soil Treated with Different Types of Organic Waste. Communications in Soil Science and Plant Analysis 41: 408-423. doi 10.1080/00103620903494368).
Domene X, Mattana S, Ramírez W, Colón J, Jiménez P, Balanyà T, Alcañiz JM, Bonmatí M (2010) Bioassays prove the suitability of mining debris mixed with sewage sludge for land reclamation purposes. Journal of Soils Sediments 10: 30-44. doi 10.1007/s11368-009-0073-1.
Domene X., Mattana S., Ramírez W., Colón J., Jiménez P., Balanyà T., Alcañiz J.M., Bonmatí M. (2009) Bioassays prove the suitability of mining debris mixed with sewage sludge for land reclamation purposes. Journal of Soils and Sediments. 10: 30-44.LinkDoi: 10.1007/s11368-009-0073-1
Background, aim, and scope: 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. Materials and methods: Two different types of mining debris from the same limestone quarry and six different types of composted or thermally dried sewage sludge were studied. A laboratory assessment was carried out by means of standardized bioassays of sludges, together with a field assessment carried out in lysimeters filled with debris-sludge mixtures. The field assessment was carried out using both the soil-waste mixtures, amended with dosages similar to those used for restoration purposes and their corresponding leachates. The variation of physicochemical properties and the outcomes of different bioassays (soil microorganisms biomass and respiration, enzymatic activities, plant emergence and growth, collembolan survival and reproduction, and the Microtox assay) were used as indicators of fertilizing or ecotoxicological effects. Results: The mining debris used in our study showed a poor capacity for biological recovery, as shown by the lower biological outcomes measured in control lysimeters compared to lysimeters amended with sludge. The addition of sludge improved debris just before the sludge application in terms of its physicochemical and biological properties (microorganism's biomass, respiration and enzymatic activities) which, in some cases, persisted after a year. Conversely, in some sludges, an inhibition in soil collembolans was observed just before the amendment, but any inhibitory effect disappeared after a year. Concerning the leachates obtained from field lysimeters after a week and a year, no inhibitory effects were detectable for aquatic bacteria. Discussion: The effects observed on some of the measured biological endpoints, both in laboratory and field assays, were mainly mediated by physicochemical parameters related to a low stability of organic matter, but in the opposite sense depending on the organism considered. Microbial parameters were enhanced when the organic matter added had a low stability (high content in labile organic matter) but, on the other hand, collembolan performance was negatively affected. The lack of toxicity of leachates indicates a low risk for groundwaters of this reclamation practice. Conclusions: The results of this study support the use of mining debris mixed with sludge for land reclamation of degraded land by quarrying. The addition of sludge allowed a quick plant cover re-establishment and provided a suitable habitat for soil biota because no long-term ecotoxicological risks were observed neither for soils nor groundwaters. The results also indicate that the environmental risk of sludges might be reduced using sludges with a high content in stable organic matter. Recommendations and perspectives: The use of mining debris mixed with sewage sludges for mining reclamation purposes is suitable since long-term ecotoxicological risks were not observed. In addition, the results support the suitability of bioassays for the prediction of the success or risk of specific land reclamation practices in order to avoid unsuccessful attempts. © Springer-Verlag 2009.
Domene X., Ramírez W., Mattana S., Alcañiz J.M., Andrés P. (2008) Ecological risk assessment of organic waste amendments using the species sensitivity distribution from a soil organisms test battery. Environmental Pollution. 155: 227-236.LinkDoi: 10.1016/j.envpol.2007.12.001
Safe amendment rates (the predicted no-effect concentration or PNEC) of seven organic wastes were estimated from the species sensitivity distribution of a battery of soil biota tests and compared with different realistic amendment scenarios (different predicted environmental concentrations or PEC). None of the wastes was expected to exert noxious effects on soil biota if applied according either to the usual maximum amendment rates in Europe or phosphorus demands of crops (below 2 tonnes DM ha-1). However, some of the wastes might be problematic if applied according to nitrogen demands of crops (above 2 tonnes DM ha-1). Ammonium content and organic matter stability of the studied wastes are the most influential determinants of the maximum amendment rates derived in this study, but not pollutant burden. This finding indicates the need to stabilize wastes prior to their reuse in soils in order to avoid short-term impacts on soil communities. © 2007 Elsevier Ltd. All rights reserved.
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