Land use affects the soil C sequestration in alpine environment, NE Italy

Soil carbon sequestration is strongly affected by soil properties, climate, and anthropogenic activities. Assessing these drivers is key to understanding the effect of land use on soil organic matter stabilization. We evaluated land use and soil depth influencing patterns of soil organic matter stabilization in three types of soil profiles located under the same pedogenetic matrix and alpine conditions but with different vegetation cover. The stock in soil organic carbon in the mean 0–20 cm layer increased from prairie (31.9 t ha−1) to prairie in natural reforestation (42 t ha−1) to forest (120 t ha−1), corresponding to increments of 1.3-fold prairie, for prairie in natural reforestation, and of 3.8-fold prairie for forest. The forest showed the highest humic carbon (21.7 g kg−1), which was 2.8 times greater than the prairie in natural reforestation and 4 times higher than the prairie. 13C-NMR spectroscopic measurements suggested a different C pattern. The prairie in natural reforestation and the prairie were characterized by a higher content in O,N-alkyl C with respect to the forest. Alkyl C and aromatic C in the prairie in natural reforestation and prairie did not show relevant differences while they decreased with respect to the forest. Carboxyl and phenolic C groups were markedly higher in forest and prairie than prairie in natural reforestation. Alkyl C, carboxyl C, and phenolic C prevailed in the Ah horizons whereas aromatic C and O,N-alkyl C were dominant in the B horizons. Overall, the marked distribution of O,N-alkyl C and alkyl C in humic substances (HS) indicates a low degree of humification. Nevertheless, in forest, the relatively high presence of aromatic C designated HS endowed with a relatively high humification degree. Thus, our results might suggest that in the alpine environment of NE Italy differences in soil organic matter (SOM) stocks and characteristics are affected by land use and anthropic activities

Jatropha Curcas Sludge Valorization

Abstract Jatropha which grows in tropical and subtropical climates across the developing world, is a perennial species that received much attention for its ability to grow on 'marginal land and to produce seeds with high oil percentage. Among the different species of Jatropha, Jatropha curcas is suitable as ornamental plant, raw material for dye, potential feed stock, soil enrichment manure and more importantly for biodiesel production. The mechanical pressing of the Jatropha seeds for oil production results in large amounts of solid residue (seed cake) and sludge that contain oil, water, minerals, proteins, toxic compounds and anti-nutritional factors. The aim of our work was to screen the fertilizing power of Jatropha sludge and its oily and solid fractions for promoting biodiesel circular economy. Our results indicated that seeds of watercress had a better germination performance than lettuce with Jatropha sludge and its fractions. This could depend on the different sensitivity of the two species and/or also to the composition of the sludge and its fractions. The solid fraction had the greatest inhibitory effects on germination of both species. The oily fraction had the less phytotoxic effect on the germination process while only in presence of the total sludge at 25%, seeds of watercress and lettuce showed a germination percentage lower than 50%. Higher concentrations were completely inhibitory. The phytotoxic effects of the sludge and its fractions may be attributed to the combination of high EC and phenol contents. This study revealed that highly diluted Jatropha total sludge may be very useful as good source of nutrients for crop production, cutting short the use of chemical fertilizers

Changes in germination and glyoxylate and respiratory enzymes of Pinus pinea seeds under various abiotic stresses

Abstract This study examined Pinus pinea seeds for their tolerance to osmotic potentials of −0.30MPa (10% polyethylene glycol [PEG]), −0.58MPa (18% PEG), −0.80MPa (21% PEG), −1.05MPa (24% PEG), pH values of 4, 5, 6, 7, 8, 9, 10, and different calcareous solutions (5, 10, 20 and 40% CaCO3). The main enzymes of glyoxylate cycle and respiratory pathway were tested. Pinus pinea seeds under no stressful condition (Control) and 5% CaCO3 reached 100% of germination. Higher concentrations of CaCO3 (20, 40%) and lower pH (4–5) adversely affected seed germination percentage, glyoxylic and respiratory enzyme activities. PEG caused the most detrimental effects on Pinus seeds; increasing the osmotic potential the germination was completely inhibited. These results suggest that Pinus pinea is able to germinate in calcareous and alkaline soils rather than in soils with lower water availability and acidic conditions

Erratum to: Biological effects of water-soluble soil phenol and soil humic extracts on plant systems

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Root plasticity improves salt tolerance in different genotypes of lentil (Lens culinaris)

Various morphological root parameters were tested in lentil seedlings in a genotype considered salt tolerant (Ustica) and in a salt sensitive one (Eston), grown on salinized soil. Apart from the root biomass production, two ecotypes showed contrasting root morphological responses and these might be partially responsible for dissimilar abilities to tolerate salinity

Land use affects the soil C sequestration in alpine environment, NE Italy

Soil carbon sequestration is strongly affected by soil properties, climate, and anthropogenic activities. Assessing these drivers is key to understanding the effect of land use on soil organic matter stabilization. We evaluated land use and soil depth influencing patterns of soil organic matter stabilization in three types of soil profiles located under the same pedogenetic matrix and alpine conditions but with different vegetation cover. The stock in soil organic carbon in the mean 0\u201320 cm layer increased from prairie (31.9 t ha1) to prairie in natural reforestation (42 t ha1) to forest (120 t ha1), corresponding to increments of 1.3-fold prairie, for prairie in natural reforestation, and of 3.8-fold prairie for forest. The forest showed the highest humic carbon (21.7 g kg1), which was 2.8 times greater than the prairie in natural reforestation and 4 times higher than the prairie. 13C-NMR spectroscopic measurements suggested a different C pattern. The prairie in natural reforestation and the prairie were characterized by a higher content in O,N-alkyl C with respect to the forest. Alkyl C and aromatic C in the prairie in natural reforestation and prairie did not show relevant differences while they decreased with respect to the forest. Carboxyl and phenolic C groups were markedly higher in forest and prairie than prairie in natural reforestation. Alkyl C, carboxyl C, and phenolic C prevailed in the Ah horizons whereas aromatic C and O,N-alkyl C were dominant in the B horizons. Overall, the marked distribution of O,N-alkyl C and alkyl C in humic substances (HS) indicates a low degree of humification. Nevertheless, in forest, the relatively high presence of aromatic C designated HS endowed with a relatively high humification degree. Thus, our results might suggest that in the alpine environment of NE Italy differences in soil organic matter (SOM) stocks and characteristics are affected by land use and anthropic activities

Effect of long-term irrigation water salinity on soil properties and microbial biomass

We assessed the effects of saline water irrigation on soil properties and microbial activity. Increasing salinity microbial activity decreased. 1% salinity strongly affected soil biochemical properties and microorganisms. Our results indicate that 0.5% salinity may be tolerated by soil microorganisms suggesting a possible use of brackish water in agriculture soils

Is chloride toxic to seed germination in mixed-salt environments? A case study with the coastal halophyte Suaeda maritima in the presence of seawater

Abstract Most salt tolerant plants, halophytes, use seed germination for natural regeneration. However, germination in mixed-salt environments such as seawater is poorly understood and ion toxicity by Cl−, the most highly concentrated ion in seawater, is rarely considered over Na+. Here, we investigate Cl− toxicity in the germination of the halophyte Suaeda maritima in the presence of artificial seawater (ASW). Seeds were germinated at 15/5 °C in dilutions of ASW and at concentrations of NaCl, MgCl2, CaCl2 and KCl as found in ASW. Solutions of polyethylene glycol (PEG) were used for osmotic comparison. Germination percentage and normal seedlings were quantified. Non-germinated seeds were tested for recovery on water. Germination rate (1/t50) was used in a halotime model to quantify the maximum concentration of Cl− (Cl−max) and Na+ (Na+max) for germination. Germination was most negatively affected when all salts were combined in the concentrations found in ASW. Recovery of non-germinated seeds from all salt treatments on water was low, but all germinated seeds formed normal seedlings. Germination on ASW was higher than on iso-osmotic solutions of PEG. The 1/t50 decreased with increasing Cl− and Na+ concentration, indicating maximum thresholds to germination at 1381 mM (Cl−max) and 1262 mM (Na+max). The results indicate that ASW does not produce an osmotic limitation to the germination of S. maritima, and exposure to salt ions can even promote germination. However, ion toxicity is the major limitation, with Cl− similarly as toxic as Na+. In mixed-salt environments such as seawater, Cl− toxicity should not be overlooked

Humic substances stimulate maize nitrogen assimilation and amino acid metabolism at physiological and molecular level

The effects of a humic substance (HS) extracted from a volcanic soil on the nitrate assimilation pathway of Zea mays seedlings were thoroughly examined using physiological and molecular approaches. Plant growth, the amount of soluble proteins and amino acids, as well as the activities of the enzymes involved in nitrogen metabolism and Krebs cycle, were evaluated in response to different HS concentrations (0, 1 and 5 mg C L−1) supplied to maize seedlings for 48 h. To better understand the HS action, the transcript accumulation of selected genes encoding enzymes involved in nitrogen assimilation and Krebs cycle was additionally evaluated in seedlings grown for 2 weeks under nitrogen (N) sufficient condition and N deprivation. HS at low concentration (1 mg C L−1) positively influenced nitrate metabolism by increasing the content of soluble protein and amino acids synthesis. Furthermore, the activity and transcription of enzymes functioning in N assimilation and Krebs were significantly stimulated. HS treatment influenced the gene expression of Zea mays plants at transcriptional level and this regulation was closely dependent on the availability of nitrate in the growth medium