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In this study, a method was developed to extract and methylate total fatty acids (TFA) from soils and sediments using an acid-catalyzed esterification--transesterification approach; the TFA method was compared with other methods in common use for fatty acids in soils. The developed method was significantly more successful in the extraction and methylation of total soil and sediment fatty acids than other methods. It also extracted long-chain hydrocarbons from soils and sediments. The TFA method is relatively simple and rapid, has high reproducibility, substantially reduced solvent use, and can easily accommodate a large number of samples at the same time. The optimized TFA method is based on a combined 'one-step' acid-catalyzed approach often used for biological tissues, oils, feedstuff, and leafy materials. Acid-catalyzed methylation is effective under many conditions, and methylates all fatty acids, including free fatty acids, fatty acid esters and amides, and fatty acid salts via both esterification and transesterification pathways. Used in conjunction with other methods, the TFA method can help to provide information about the distribution of ester-linked fatty acids and free fatty acids or fatty acid salts in soils and sediments. Abbreviations: EL, ester linked; FAME, fatty acid methyl ester; GC-MS, gas chromatographmass spectrometer; HT-EL, high-temperature ester linked; MTBE, methyl tert-butyl ether; PLFA, phospholipid fatty acids; TFA, total fatty acids. doi:10.2136/sssaj2009.0127

BACKGROUND The influence of various biochars on crop yield and disease resistance of Capsicum annuum L. (sweet pepper) under modern, high input, intensive net house cultivation was tested over the course of 2011-2014 in the Arava desert region of Israel. A pot experiment with Lactuca sativa L. (lettuce) grown in the absence of fertilizer employed the 3-year-old field trial soils to determine if biochar treatments contributed to soil intrinsic fertility. RESULTS Biochar amendments resulted in a significant increase in the number and weight of pepper fruits over 3 years. Concomitant with the increased yield, biochar significantly decreased the severity of powdery mildew ( Leveillula taurica) disease and broad mite ( Polyphagotarsonemus latus) pest infestation. Biochar additions resulted in increased soil organic matter but did not influence the pH, electrical conductivity or soil or plant mineral nutrients. Intrinsic fertility experiments with lettuce showed that two of the four biochar-treated field soils had significant positive impacts on lettuce fresh weight and total chlorophyll, carotenoid and anthocyanin contents. CONCLUSION Biochar-based soil management can enhance the functioning of intensive, commercial, net house production of peppers under the tested conditions, resulting in increased crop yield and plant resistance to disease over several years. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]