Papers by Diego Pizzeghello
In alpine environments, colonies of snow vole (Chionomys nivalis Martins) cause strong pedoturbat... more In alpine environments, colonies of snow vole (Chionomys nivalis Martins) cause strong pedoturbation, which may affect humification process and soil organic matter (SOM) cycling, with repercussions on the hormone-like activity of organics. We investigated the effect of snow vole pedoturbation on the chemical and spectroscopic features of soil organic fractions, and the potential hormone-like activity of humic and fulvic acids (HA, FA). The study site was located on the high-mountain environment of the Majella massif (central Italy). Pedoturbated and regular soils were morphologically described and characterized for pH and content of total organic carbon, total extractable carbon, HA, and FA. Both HA and FA were extracted and investigated using attenuated total reflectance/Fourier transform infrared (ATR/FTIR), nuclear magnetic resonance with high-resolution magic angle spinning (HRMAS-NMR), and 1 H-13 C heteronuclear single quantum coherence (HSQC). HA and FA were also tested for their auxin-like and gibberellin-like activities. Results provide evidences that bioturbated and regular soils contain a poorly decomposed SOM, but HA and FA with a well-defined molecular structure. The HA and FA from both biotur-bated and regular soils show a hormone-like activity with a different allocation along the soil profile. In the regular soil, the highest auxin-like activity was shown by HA and FA from Oe1 horizon, while gibberellin-like activity was expressed by FA from Oe2 horizon. Burrowing activity determines a redistribution of organics throughout the profile with a relatively high auxin-like activity in the FA from straw tunnel wall (STW) and gibberellin-like activity in the HA from vole feces (VF). The relative high presence of carboxylic acids, amides, proteins, and amino acids in the FA from STW and the aromatic moieties in the HA from VF put evidences for their different behavior. The fact that snow vole activity has modified the chemical and biological properties of SOM in these soils otherwise considered governed only by low temperature has important ecological implications such as the preservation of soil fertility and vegetal biodiversity.
Increasing attention has been devoted in the last few years to the mechanisms by which humic subs... more Increasing attention has been devoted in the last few years to the mechanisms by which humic substances (HS) influence plant growth. Nevertheless, among the biologically active compounds that might be present in HS, only indoleacetic acid has been identified. An enzyme-linked immunosorbent assay (ELISA) was applied to detect the presence of isopentenyladenosine (IPA), a cytokinin, in two lignosulphonate-humates, leonardite humic acid and in a high molecular weight humic fraction extracted from earthworm faeces. The IPA concentration ranged from 34 to 145 pmol mg -1 humic C and was estimated by using a linear dose-response curves between the carbon (C) concentration and percentage of binding of an anti-IPA monoclonal antibody. The cytokinin-like activity of HS was evaluated by weighing small radish (Raphanus sativus L.) cotyledon leaves and measuring chlorophyll and protein contents, the activities of ATP sulfurylase and O-acetylserine sulfhydrylase on maize plants. It is noteworthy that, among the four HS, those from earthworm faeces showed the highest amount of IPA and the strongest cytokinin-like activity in both plants. The presence of IPA confirmed that HS influence plant metabolism at different levels. Our results open new perspectives in the plant-HS relationship and shed new light on the active components of HS.
The long-term evolution (44 years) of phosphorus (P) in 1-m profile of three reconstructed soils ... more The long-term evolution (44 years) of phosphorus (P) in 1-m profile of three reconstructed soils (0–80 cm = sandy, SDY; clay, CLY; and peaty, PTY; 80–100 cm = native layers) typical of the Po Valley (northern Italy) has been studied in a factorial experiment with farmyard manure and mineral fertilizer. Calcium, magnesium, aluminium, and iron concentrations were determined as total (Ca T , Mg T) and pseuto-total (Al PT and Fe PT) amounts and as extractable forms by Mehlich-3 (M3) and ammonium oxalate (Ox) extracting solutions. The P distributions in total P (TP), organic P (P org), H 2 SO 4 P (P H 2 SO 4), and the more mobile NH 4 F P (P NH 4 F) and NaOH P (P NaOH) were also measured. As expected soil type always influenced P sorption related soil properties. Ca M3 /Ca T ratios indicated the presence of easily dissolved/released Ca in PTY while Al and Fe dominated in CLY and PTY soils as crystalline and poorly crystalline oxides forms. Treatments affected the pseudo-total Al and Fe with higher contents in manure than mineral, whereas mineral induced higher oxalate/total ratios of both Fe and Al than manure and untreated. Treatment affected the P content with a pattern strongly influenced by soil type and depth. Despite the comparable P balance between mineral and manure, P forms were generally higher in amended plots than mineral fertilized. Manure increased P H 2 SO 4 down to 50 cm in CLY and down to 80 cm in SDY and PTY. High values of P NaOH were also induced by manure throughout the 0-80 cm of SDY. The occurrence of leaching process has been indicated by the general change in some P sorption related properties and P forms found in the native layers. In particular, both stable (i.e. TP) and labile forms (i.e. P NaOH) increased following 44 yr of fertilization. The phenomenon occurred not only in the overfertilized SDY but also in CLY and PTY where the P balance was negative. Long-term factors influencing the mobility of P within the soil profile are due not only to excessive P inputs, but also the forms of P fertilizer applied.
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Papers by Diego Pizzeghello