1,721,149 research outputs found
Reazione del Suolo
No full textLa reazione è il singolo parametro capace di fornire il maggior numero di informazioni relative alle proprietà del suolo. In questo capitolo si esaminano i principali fattori capaci di determinarla, le sue relazioni con la fertilità del suolo ed i metodi analitici che ne permettono la determinazione
Phosphorus in Digestate-Based Compost: Chemical Speciation and Plant-Availability
No full textA compost (CHW) from the residue of the dry-batch digestion of household waste and one (CSD) from the solid fraction of anaerobically digested maize were tested for their phosphorus (P) release by means of sequential extraction. The products were then compared in a soil incubation (30 mg P kg-1) for their capacity to supply potentially available P (Olsen-P), and in a pot trial to test plant-available P on Italian ryegrass over 112 days. A municipal solid waste compost (MSWC) and an inorganic P source (P-chem) were added as reference in addition to a not-fertilized control (Control). Sequential extraction showed that CSD had the greatest labile P (NaHCO3 30%> H2O 29%> HCl 23%> NaOH 10%). On the contrary, CHW showed the greatest recalcitrant P (HCl 44%> NaHCO3 10%> H2O 11%> NaOH 8%), being similar to MSWC (HCl 65%> NaOH 13% NaHCO3 12%> H2O 5%). This was in agreement with the different amorphous or crystalline degree of the sample as determined by XRD. Also in soil, CSD showed the highest level of Olsen-P at the beginning of incubation (28.5 mg kg-1), while CHW and MSWC had the lowest level of Olsen-P throughout incubation (4.6 and 6.0 mg kg-1 on average), very close to the Control (3.0 mg kg-1). Plant test showed that CSD also had the greatest available P (ARF: 12.5%), followed by P-chem (5.6%)> MSWC (4.2%)> CHW (2.5%). From sequential extraction and physical analysis, it therefore appears that the presence of significant amounts of Ca, such as in CHW and MSWC, shifted P toward low soluble Ca-P compounds, thus reducing the P available for plant nutrition
RELATIONSHIPS BETWEEN STABILITY, MATURITY, WATER EXTRACTABLE ORGANIC MATTER OF MUNICIPAL SEWAGE SLUDGE COMPOSTS AND SOIL FUNCTIONALITY
No full textCompost capability of restoring or enhancing soil quality depends on several parameters, such as soil characteristics, compost carbon, nitrogen and other nutrient content, heavy metal occurrence, stability and maturity. This study investigated the possibility of relating compost stability and maturity to water-extractable organic matter (WEOM) properties and amendment effect on soil quality. Three composts from municipal sewage sludge and rice husk (AN, from anaerobic wastewater treatment plants; AE, from aerobic ones; MIX, from both anaerobic and aerobic ones) have been analysed and compared to a traditional green waste compost (GM, from green manure, solid waste and urban sewage sludge). To this aim, WEOMs were characterized through chemical analysis; furthermore, compost stability was evaluated through oxygen uptake rate calculation and maturity was estimated through germination index determination, whereas compost impact on soil fertility was studied, in a lab-scale experiment, through indicators as inorganic nitrogen release, soil microbial biomass carbon, basal respiration rate and fluorescein di-acetate hydrolysis. The obtained results indicated that WEOM characterization could be useful to investigate compost stability (which is related to protein and phenol concentrations) and maturity (related to nitrate/ammonium ratio and degree of aromaticity) and then compost impact on soil functionality. Indeed, compost stability resulted inversely related to soil microbial biomass, basal respiration rate and fluorescein di-acetate hydrolysis when the products were applied to the soil
Organic wastes as alternative sources of phosphorus for plant nutrition in a calcareous soil
No full textRecycled organic wastes (OW) can be a valuable P source; however, their P-fertilising capacity is still poorly known. In this study, we selected three anaerobic digestates [wastewater sludge (D-1), winery sludge (D-2), and bovine-slurry/energy crops (BD)] and two animal effluents [bovine slurry (BS) and swine slurry (SS)] to test their P-release and P-fertilising capacities via sequential chemical extraction (SCE), X-ray diffraction (XRD), and P-31-nuclear magnetic resonance (P-31 NMR). Subsequently, the three digestates (30 mg P kg(-1) of soil) were compared for the release of Olsen-P during a soil incubation and for plant-P apparent recovery (ARF) in a pot experiment using ryegrass (112 days) in a soil with poorly available-P (Olsen-P < 5 mg kg(-1)), under a non-limiting N environment. The amount of labile-P (H2O + NaHCO3), as determined from SCE, related well to the Olsen-P following OW addition to the soil. It was shown via P-31 NMR spectroscopy that orthophosphate was the leading P-form in highly P-releasing OW. The amount of labile-P, however, was affected by soil adsorption, thereby reducing plant-P uptake. The plant-P ARF (%) showed that the recycled P-sources were clustered in highly (BD and SS: approximate to 20%), intermediately (D-1 and BS: approximate to 15%) and poorly performing OWs (D-2: approximate to 10%) vs. chemical P-source (P-chem: 20%). Therefore, only BD and SS were effective alternatives to P-chem; however, the other OW can be efficient P-sources in soils with higher Olsen-P. Thus, crop fertilisation can be tailored on a P-basis by SCE as a function of soil adsorption capacity and on an N-basis according to the demand. (C) 2019 Elsevier Ltd. All rights reserved
Fate of N in soil amended with 15N-labelled residues of winter cereals combined with an organic N fertilizer
No full textIn organic farming winter cereals, as cover crops, provide nutrients, when they return to soil as crop residues. The fate of N deriving from two decomposing 15N-labelled winter cereals, with or without the supply of an organic N fertiliser, was studied in a field experiment. The stabilisation of residues N in soil aggregates and the portion lost from the system were also evaluated. Barley or triticale residues were incubated alone or with hydrolysed leather (L) in mesocosms over one year. The residues derived N was measured in soil and in soil aggregate size fractions >250m (macroaggregates, macro); 53-250m (microaggregates, micro); <53m (silt and clay, s+c) obtained by wet sieving. Barley degradation (77% of the initial amount) was faster than triticale degradation (55%). The L slowed down the barley degradation (72%) and speeded that of triticale (64%). Greater amount of residues N was in macro and micro than in s+c. The presence of L reduced the residues N stabilised in the finest fractions. The losses of barley N were reduced by the L addition, those from triticale were increased. The fate of residues N was affected by the L application that influenced the residues mineralisation, the stabilisation and the losses of their derived N
Carbon sequestration and distribution in soil aggregate fractions under Miscanthus and giant reed in the Mediterranean area
No full textIn this study, we assessed the carbon (C) distribution within soil aggregates, macroaggregates (Macro),
microaggregates (micro), and silt and clay (s + c) through three soil depths (0– 0.15, 0.15–0.30, and 0.30–
0.60 m) and af ter 9 years of land conversion from two annual crops continuous wheat and maize/wheat
rotation to Miscanthus and giant reed, respectively. The 13 C natural abundance analysis wa s combined
with physical fractionation to trace the fate of the new C that wa s derived from Miscanthus and giant reed
in aggregate fractions. Macro always represented the highest proportion of the soil and the highest
amount of C. In Miscanthus, the amount of C decreased from the 0–0.15 to the 0.30–0.60 m soil layer,
whereas the C storage capacity of micro and s + c increased with depth. In giant reed, the distribution of
the soil fractions and the associated C were more uniform in all of the layers. The new C derived from the
perennial species wa s mainly concentrated in the upper layer in the Macro under Miscanthus , whereas it
wa s more evenly distributed in the three layers and the fractions under giant reed. Irrespective of the
fractions, in the Miscanthus plantation, the great C accumulation wa s derived from both the new C
directly entering the soil and the old C that wa s preserved from mineralization. Conversely, in the giant
reed plantation, C accumulation wa s only derived from the new C component. These patterns reflect the
different structure of the root apparatus of the two perennial species, which were mainly concentrated in
the upper layer of Miscanthus and were more evenly distributed in soil profile of the giant reed. It is likely
that this is responsible for the different mechanisms of C storage and turnover
Compost improves plant and soil macronutrient content in a 14-years orchard
Full text linkAdequate plant nutritional status and soil fertility preservation can be achieved through sustainable agricultural management techniques. The challenge of intensive orchard cultivation, besides the risk of nutrient decline, is to prevent the loss of soil fertility that could lead to soil degradation with a consequent negative impact on yield and fruit quality. The use of organic amendments could be a sustainable strategy to combine high plant performance with soil fertility improvement. This work aims at shedding light on the effects of compost addition with respect to an unfertilized control and a mineral fertilization treatment on macronutrient (K, Ca, Mg, and S) dynamics in plants and soil of a commercial nectarine orchard planted in 2001. In the first 0.15 m of soil, compost addition resulted in higher values (26–42%) of all the parameters. Both fertilization treatments induced a 28% increase in roots’ S content compared to the control but did not induce macronutrient content variation in plant skeleton, pruned wood, and thinned fruits. In autumn leaves, all the macronutrients resulted in higher values (24–45%) with both mineral and compost fertilization, and the same was observed in fruit at harvest (increases of 15–31%). In our study, the treatment with compost satisfied plants' nutrient demands as much as the mineral fertilizer. In addition, compost treatment also improved soil nutrient content while preserving yield. Our results show that it is possible to reconcile plant nutrient needs with the preservation of soil fertility with the aim of improving sustainability of agriculture
Organic wastes as alternative sources of phosphorus for plant nutrition in a calcareous soil
No full textRecycled organic wastes (OW) can be a valuable P source; however, their P-fertilising capacity is still poorly known. In this study, we selected three anaerobic digestates [wastewater sludge (D1), winery sludge (D2), and bovine-slurry/energy crops (BD)] and two animal effluents [bovine slurry (BS) and swine slurry (SS)] to test their P-release and P-fertilising capacities via sequential chemical extraction (SCE), X-ray diffraction (XRD), and 31P-nuclear magnetic resonance (31P NMR). Subsequently, the three digestates (30 mg P kg−1 of soil) were compared for the release of Olsen-P during a soil incubation and for plant-P apparent recovery (ARF) in a pot experiment using ryegrass (112 days) in a soil with poorly available-P (Olsen-P < 5 mg kg−1), under a non-limiting N environment. The amount of labile-P (H2O + NaHCO3), as determined from SCE, related well to the Olsen-P following OW addition to the soil. It was shown via 31P NMR spectroscopy that orthophosphate was the leading P-form in highly P-releasing OW. The amount of labile-P, however, was affected by soil adsorption, thereby reducing plant-P uptake. The plant-P ARF (%) showed that the recycled P-sources were clustered in highly (BD and SS: ≈20%), intermediately (D1 and BS: ≈15%), and poorly performing OWs (D2: ≈10%) vs. chemical P-source (P-chem: 20%). Therefore, only BD and SS were effective alternatives to P-chem; however, the other OW can be efficient P-sources in soils with higher Olsen-P. Thus, crop fertilisation can be tailored on a P-basis by SCE as a function of soil adsorption capacity and on an N-basis according to the demand
Biodegradable plastics: Effects on functionality and fertility of two different soils
Full text linkIn agriculture, the use of soil biodegradable mulch films could represent an eco-friendly alternative to conventional
plastic films. However, soil biodegradable mulch films incorporated into the soil through tillage, being not
only a physical but also a biogeochemical input, is expected to influence the soil quality by affecting its functions.
Therefore, the eco-compatibility of these biodegradable plastics needs to be evaluated for their impact on
different soil functions. To understand the effect of biodegradable plastics on soil quality (i.e. microbial biomass,
nitrogen cycle, and activity of soil enzymes involved in the biochemical processes of carbon and nitrogen), we
added increasing quantities of biodegradable plastics in two different soils: a loamy (Cambisol) and sandy
(Arenosol) soil. The results highlight that the carbon added through the biodegradable plastics influenced the
processes linked to carbon and nitrogen cycles. Significant effects were observed mainly with the highest dose of
biodegradable plastics added (1%), resulting in a higher growth of microbial biomass, increased carbon mineralisation,
and increased immobilisation of available nitrogen. The results also underline the importance of
evaluating the impact of biodegradable plastics in different soils because all the processes considered are also
influenced also by soil physicochemical characteristics
Conventional versus organic management: application of simple and complex indexes to assess soil quality
Full text linkOrganic management aims to maintain and/or enhance the soil quality by adopting crop rotation, reduced
tillage, and application of organic fertilizers. Several studies highlight the advantages of organic management in
terms of soil quality and soil fertility, the key themes in sustainable agronomy. The aim of this study was to
understand whether there were differences in soil quality between two different approaches of organic management.
Soil quality was assessed using a set of biochemical parameters individually or in combination, in
simple and complex indexes, respectively. Soil samples were procured from a long-term field experiment area
located in Monsanpolo del Tronto (Central Italy) in which conventional (Conv), and two different organic
managements (Org1, organic traditional; Org2, organic agroecological) were followed, and were assessed for soil
quality. Results from individual soil properties, simple and complex indexes highlighted that Conv and Org1
were similar in terms of acquisition activity indicating that both mineral and organic fertilizers supply C, N, and
P equally to agro-ecosystems. However, in Org2, despite theoretical imbalances in terms of C:N:P, microbial
activity efficiently filled this imbalance without affecting soil organic carbon content. The indexes showed a
positive metabolic response and a higher soil quality in both the organically managed plots, indicating that
organic management, independent of the agronomic approach, maintains the soil quality despite the differences
in biochemical processes. Moreover, simple and complex soil quality indexes were sensitive enough to
discriminate the two organic management strategies
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