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Intensive agricultural practices have resulted in progressive soil degradation, with consequences on soil ecosystem services. The inclusion of service crops is a promising alternative to support the sustainability of the agricultural system. The aim of this study was to analyze in a six-year field experiment the effect of Brachiaria brizantha (perennial tropical grass) and Zea mays as service crops in a degraded common bean monoculture system in northwest Argentina. After six years, service crop treatments revealed a significant increase in most physical, chemical and biological properties of the soil (enzyme activities, microbial biomass, respiration and glomalin-related soil protein), compared with common bean monoculture. Also, a lower disease incidence was observed under B. brizantha treatments, associated with increased populations of Trichoderma spp. and Gliocladium spp. The phospholipid fatty acid profiles detected higher values of total microbial biomass under service crops. Our results suggest that the inclusion of several cycles of B. brizantha constitutes a promising soil management for recovering degraded agroecosystems.

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Lead-polluted agricultural soils are a serious problem for food safety, with organic amendment being a promising mitigation method from the environmental perspective. Therefore, the purpose of this study was to evaluate lead availability and the effectiveness of the application of compost of biosolid with wood shavings and yard trimmings in contaminated soils. The physicochemical (Pb distribution, organic matter, pH, electric conductivity, cation exchange capacity, nitrogen, phosphorus, carbon, carbonates, exchangeable cations, sodium) and biological parameters (the microbial activity obtained by fluorescein diacetate hydrolysis) in Pb-polluted and non-polluted agricultural soils were evaluated after the addition of biosolid with wood shavings and yard trimming compost. Topsoils (lead-polluted and control) were collected in the vicinity of a former battery-recycling plant, amended with compost (0%, 5%, and 10%), and incubated in controlled conditions for 118 days. The results showed that lead availability decreased significantly, and the nutritional quality of the soils increased in the soils amended with 10% of compost. Taken together, the results of the present study indicated that compost amendment could be an effective method for mitigating the negative effects of lead in agricultural soils.

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The purpose of this work was to investigate the effects of spreading olive oil mill wastewater (OMWW) on soil biochemical parameters and olive production in an organically managed olive orchard. The experiment was carried out with three different doses of OMWW (80, 160 and 500 m(3) ha(-1)) and a control (untreated soil). Three samplings were done at 10, 30 and 90 days after the administration of the byproduct. OMWW application differentially modified the biochemical properties of the soil analyzed. Organic matter, organic carbon, total nitrogen and extractable phosphorus soil contents increased proportionally with each increasing dose. The values of these parameters decreased gradually with time. Total microbial activity was altered and the OMWW 500 m(3) ha(-1) treatment proved to be the most active when compared with the other applied doses. OMWW agricultural application also modified the structure of soil microbial communities, particularly affecting Gram positive and negative bacteria, while fungal biomass did not show consistent changes. Although there was a salinity increase in the treated soil, especially at the highest dose, the productive parameters analyzed (fruit and oil tree(-1)) were not affected. In light of the obtained results, we consider that low dose of OMWW could be considered an alternative farming practice for semiarid regions.

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BACKGROUND: In the last few years, agricultural uses of waste waters from olive processing-related industries have been gaining interest mainly with a view to composting or bio-fertilizers. The present work examines physico-chemical, toxicological and geno-toxicological properties of three liquid wastes, namely olive mill wastewater (OMWW), olive wet husk and olive brine. The effect of OMWW spreading on soil microbial activity and biomass was also evaluated. RESULTS: Data from Artemia salina and Lactuca sativa toxicity tests indicated high levels of lethality, and inhibitory effects on seed germination and seedling growth of all olive wastes. The genotoxicity assays using Allium cepa tests showed contrasting results. At high concentrations, olive wastes caused inhibition or suppression of mitosis. However, they did not produce induced anaphase aberrations. Data on reversion of Salmonella thyphimurium strains using the Ames test indicated that the olive wastes did not present mutagenic activity. Results from the field experiment showed that OMWW at a 500 m(3) ha(-1) had the highest values of both soil microbial activity and biomass after 3 months of the amendment application. CONCLUSION: This work adds new data for environmental risk assessment of olive industrial wastes. Direct use of olive wastes for agricultural purposes should be limited owing to their possible chemotoxic, phytotoxic and antimicrobial effects.

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The use of compost amendments to bioremediate potential organic pollutants in agricultural soils has recently become an increasingly important field of research. Although several fungicides have been extensively used to control a wide range of soil-borne fungal diseases, little is known about the impact of applying these pesticides on the structure and function of microbial communities in soils amended with vermicompost. The aim of this study was to evaluate the effect of a combined treatment of iprodione and vermicompost on soil microbiological parameters under laboratory conditions. The study was carried out on agricultural and grassland soils to identify the effect of iprodione application at field rate (FR) and 10-times FR (10 FR) with and without vermicompost (VCH) on iprodione breakdown, fluorescein diacetate activity (FDA), total fatty acid methyl ester (FAME) profiles, total protein content, and protein profiles by using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Our results indicate that the addition of vermicompost decreased the iprodione breakdown at days 30 and 60 in non-sterilised agricultural soil and at 60 days in sterilised and non-sterilised grassland soil. Independent of vermicompost amended treatments, iprodione was found to mainly alter microbial communities after 30 days of incubation. On day 30, separation between communities treated with iprodione 10 FR and iprodione 10FR + VCH treatments were well defined in both agricultural and grassland soils. Within each soil type, our results showed no difference in the total protein content. However, the protein content in the grassland soil was clearly higher than in the agricultural soil. SDS-PAGE gels revealed that the treatments applied to the agricultural soil using iprodione at the highest dosages (iprodione 10FR and iprodione 10FR+VCH) resulted in an alteration of the band pattern. In conclusion, the experiments revealed that the addition of vermicompost may decrease the breakdown of iprodione in soils. Furthermore, elevated dosages of iprodione may potentially affect the microbial community structure and diversity of the soil, which may lead to the deterioration of soil quality and fertility.

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The chemical composition of the leaf oils of five Juniperus species (Juniperus sabina L., Juniperus communis Lam., Juniperus scopulorum Sarg., Juniperus virginiana L., Juniperus chinensis L., Cupressaceae) was determined by co-chromatography with authentic samples, GC-MS and Kováts retention indices. Sabinene was the most abundant component in the oils of Juniperus from western Patagonia Argentina. However, limonene and germacrene B constituted 25.1 percent and 11.5 percent of the oil of J. sabina. J. virginiana showed high concentration of alpha-humulene and limonene (31.4 and 15.9 percent respectively), while isobornyl acetate and germacrene B were also the main compounds of J. chinensis. Essential oils extracted of Juniperus were evaluated in vitro for their efficacy against Fusarium verticillioides, Aspergillus flavus, Aspergillus parasiticus, Candida albicans and Rhodotorula infection. Candida albicans was not inhibited for the essential oils of Juniperus. However, F. verticillioides, A. flavus, A. parasiticus and Rhodotorula were inhibited for these oils.

La composición de los aceites esenciales de la hoja de cinco especies de Juniperus (Juniperus sabina L., Juniperus communis Lam., Juniperus scopulorum Sarg., Juniperus virginiana L., Juniperus chinensis L., Cupressaceae), se determinó mediante una co-cromatografía con muestras auténticas de dos columnas de diferente polaridad, CG-EM y los índices de retención de Kovats. El sabineno fue el componente más abundante en los aceites de Juniperus del oeste de la Patagonia Argentina. Sin embargo, el limoneno y el germacreno B son otros componentes importantes del aceite esencial de J. sabina con el 25,1 por ciento y 11,5 por ciento respectivamente. En J. virginiana el alfa-humuleno y el limoneno (con el 31,4 por ciento y 15.9 por ciento respectivamente) mostraron ser también importantes, mientras que el acetato de isobornilo y el germacreno B fueron también los principales componentes de la J. chinensis. Los aceites esenciales extraídos de Juniperus se evaluaron in vitro para determinar su eficacia contra Fusarium verticillioides, Aspergillus flavus, Aspergillus parasiticus, Candida albicans y Rhodotorula. Candida albicans no se inhibió por la acción de los aceites esenciales de Juniperus. Sin embargo, F. verticillioides, A. flavus, A. parasiticus y Rhodotorula fueron inhibidos.

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