Crop rotation in no‐till soils modifies the soil fatty acids signature

Abstract

Analysis of whole‐soil fatty acids (WSFA) was used to characterize no‐till productive agricultural soils associated with different crop rotation managements on the Argentinean pampas, over two sampling seasons. Crop rotation (CR) treatment was compared with soybean monocropping (MC). Soils from nearby natural environments (NE) were used as reference treatments. The objective of this study was to characterize the soil lipid signature and seek putative markers of agricultural management. NE sites had greater concentration of total WSFA than agricultural sites, but no differences between CR and MC were identified. NE sites were characterized by straight chain and mono‐unsaturated fatty acids, such as 16:1ω5c, an established biomarker for arbuscular mycorrhiza. Comparing lipid profiles using multivariate methods allowed a comprehensive comparison among treatments. The CR and NE soil samples were more alike than those of MC, with several fatty acids in common. CR soils were associated with mixed, branched and hydroxylated fatty acids. MC profiles appeared to be enriched by 16:010Me and 18:1ω7c fatty acids, which could be potential treatment markers. Thus, use of the WSFA approach to study soil lipid signature appeared to be a sensitive method to characterize soil health and soil use and management. However, some of the fatty acids do not come from living cells but from soil organic matter, which sets a limitation on interpretation in terms of the microbial community but expands the biological origin of the soil lipid signature to any biological matter, alive or death, which is a constitutive part of the soil under study.

Soil physiology discriminates between no‐till agricultural soils with different crop systems on winter season

“…It has been previously shown for the same soils of the present study that the differences in agricultural practices modify the bacterial diversity at the regional level (Rosa et al., ); it was also possible to detect taxonomic groups of bacteria that are responders to the different agricultural practices despite the type of soil (Figuerola et al., ), and in these soils to detect differences in the fatty acid profiles of phospholipids, neutral lipids and whole soil fatty acids that discriminate between treatments (Ferrari et al., , ). Other quantitative arguments regarding levels of organic matter have shown that crop rotation compared with monocropping enhances the concentration of soil organic carbon (SOC) and carbohydrates in the soil (Duval et al., ).…”

“…Another influence would probably be the weather, which plays a major role in seasonal effect, as soil temperature partly influences soil activity (Davidson & Janssens, 2006). The fatty acid profiles obtained from the same soil samples as the ones used in the present work showed that both bacteria and fungi are reduced from summer to winter and that the differences between agricultural practices also become clearer in winter than in summer samples (Ferrari et al, 2015(Ferrari et al, , 2018.…”

“…The Argentinean Association of No‐till Farmers (AAPRESID) is demanding new soil health indicators of short‐term responses (Wall, ). The number of studies of biological indicators in no‐till agriculture in Argentina is increasing (Agaras, Wall, & Valverde, ; Bedano, Domínguez, Arolfo, & Wall, ; Ferrari, Ravnskov, & Wall, ; Ferrari et al., ; Figuerola, Guerrero, Türkowsky, Wall, & Erijman, ; Figuerola et al., ; Montecchia et al., ; Romaniuk, Giuffré, Costantini, Bartoloni, & Nannipieri, ). Various biological and biochemical soil properties, such as lipid signature (Ferrari et al., ), bacterial responders to soil management (Figuerola et al., ) and community level physiological profiles (CLPPs) (Garland et al., ; Zabaloy, Garland, & Gomez, ; Zabaloy, Gómez, Garland, & Gómez, ; Zabaloy, Lehman, Frey, & Garland, ), appear as potential indicators for monitoring soil quality (Filip, ; Ritz, Black, Campbell, Harris, & Wood, ).…”

Agriculture by Irrigation Modifies Microbial Communities and Soil Functions Associated With Enhancing C Uptake of a Steppe Semi-Arid Soil in Northern Patagonia

“…Whole soil fatty acids analysis (WSFA) was run according to Ferrari et al (22). In brief, 1 g of freeze-dried and liquid N 2 milled soil sample was saponified with a NaOH-methanol mixture and methylated with HCl-methanol.…”

“…Fatty acids were analyzed through the MIDI microbial identification protocol (Sherlock R Microbial Identification System, version 6.2 and the RTSBA6 aerobe library). Nomenclature of fatty acids and grouping by chemical functions were done according to Ferrari et al (22). The concentration of each fatty acid identified by the MIDI software was assessed concerning the 19:0 standard and expressed as nmol g −1 .…”