1,721,012 research outputs found
Fertilizing potential and CO2 emissions following the utilization of fresh and composted food-waste anaerobic digestates
Full text linkWet and dry-batch anaerobic digestion, and composting are common technologies in food waste (FW) management, resulting in different outputs. However, the effects of composting on carbon dioxide (CO2) emissions, nitrogen (N) and phosphorus (P) fertilizing capacity in view of closing nutrient cycle are still poorly investigated. In this work, two FW anaerobic digestates from the wet (D1) and dry-batch process (D2), and their respective composts (C1 and C2) were tested in a soil incubation (84 days at 25 °C) to assess CO2 emissions in comparison with a mixed (animal slurry/energy crop) digestate (BD) and a reference municipal solid waste compost (MSWC). The same products were also tested for the relative P efficiency (RPE) in soil, in comparison with a chemical-P source (30 mg P kg−1). Lastly, the apparent recovery fraction of N (N-ARF) from the five organic products was determined in a pot test with ryegrass (84 days; 300 kg available N ha−1), compared to a chemical fertilizer (NPK). Composting strongly reduced net-CO2 emissions compared to the two digestates (625 vs. 2850 mg CO2 kg−1 soil). Oppositely, composting very modestly influenced RPE that ranged around 100–90% in D1 and C1, and ≈30% in D2 and C2. Moreover, composting did not significantly reduce N-ARF that ranked in descending order as follows: NPK (77.5%) > D1 = BD (17.7%) ≥ C1 (14.7%) > MSWC (3.6%) > D2 (1.2%) > C2 (−3.1%). Composting was shown a reliable strategy for FW digestate management, as it reduces potential CO2 emission without affecting these products' N- and P-fertilizing capacity
A Nitrification Inhibitor, Nitrapyrin, Reduces Potential Nitrate Leaching through Soil Columns Treated with Animal Slurries and Anaerobic Digestate
Full text linkA leaching experiment was designed to study the effects of a commercial nitrification inhibitor containing nitrapyrin on nitrification, microbial nitrogen (N) immobilization, and nitrate leaching. Soil columns were treated with 100 mg N kg−1 from pig slurry, cattle slurry, and anaerobic digestate in a mixture with or without the nitrification inhibitor. Destructive sampling was carried out after 0, 7, and 28 days of incubation in the dark at 18 °C. At each sampling date, artificial rain (200 mm of 0.01 M calcium chloride over 4 h) was added to the soil columns. The leachate was collected, and the soil was removed from the columns and sectioned into 5 cm segments. Results indicated that after 28 days of incubation, nitrapyrin enhanced ammoniacal N accumulation in the top layers of the soil columns and reduced the nitrate concentration in the leachates with pig slurry and anaerobic digestate. Furthermore, in the soil columns treated with anaerobic digestate, nitrapyrin promoted microbial N immobilization. These findings suggest that the use of nitrapyrin in a mixture with animal slurry and anaerobic digestate has the potential to reduce nitrate leaching and increase N retention in the topsoil, affording both environmental and economic advantages
Rapid assessment of fertilizers manufacturing methods by means of a novel waveguide vector spectrometer
Full text linkThis study aims to test the suitability of a waveguide spectrometer, as a rapid and cheap tool to discriminate between different fertilizers according to two different manufacturing methods, such as granulation and blending.
The tested instrument is a waveguide vector spectrometer, patented in 2016, that operates in the range 1.6-2.7 GHz, giving both spectral phase and gain measurements. Granulated and blended fertilizers were dehydrated and pulverized to avoid possible interferences due to the water content and the geometry of the sample. The spectral data were analysed by multivariate statistical analysis [principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA)] in order to obtain a discrimination tool considering the whole hidden spectral information.
PC1 (95% of the explained variance) and PC2 (4% of the explained variance) are shown to explain most of the spectral variability. A tendency to group samples according to the different production methods can be seen, even if the discrimination is influenced by the different chemical compositions of fertilizers. However, PLS-DA models correctly classified 100% of the samples into granulated and blended classes using spectra obtained by waveguide spectroscopy.
Despite being preliminary, the tests carried out on a small number of samples show how the technique coupled with PLS-DA models could be able to discriminate between the analysed fertilizers by means of their spectral signature and according to the manufacturing method, if the chemical composition is kept constant. Further tests are necessary to validate the model, also considering the possibility of grouping fertilizers on the basis of their similar composition
Efficienza d'uso del P nel medio-lungo periodo in seguito all'impiego di compost
No full textGli ammendanti compostati (compost) possono rappresentare una fonte di fosforo (P) alternativa a quello minerale, risorsa non
rinnovabile, tuttavia poco si conosce sulla loro capacità di fornire P disponibile per la nutrizione vegetale. In questo lavoro
quattro compost (ACV; ACM 1; ACM2; ACF), sono stati testati per la loro capacità di fornire P nel corso di due cicli di coltivazione di
loietto in vaso: senza / con ausilio di fertilizzazione azotata (N-;N+; 112+112 gg). In N- solo ACM1 e ACF presentavano asportazioni di P maggiori rispetto al fertilizzante chimico N-P-K (+5%). In N+ tutti i compost presentavano asportazioni di P superiori a N-P-K (+7%), a parte ACV (-5%). I compost possono rappresentare una fonte di P disponibile alla nutrizione vegetale nel medio-lungo periodo,
lasciando nel suolo dotazioni interessanti di P potenzialmente disponibile ad un successivo ciclo colturale, al contrario di quanto
evidenziato con la fertilizzazione fosfatica chimica.Summary Compost may represent a source of phosphorus (P) alternative to the mineral one, a non-renewable resource, but little is known about their capacity to provide plant-available P. In this article four compost (ACV, ACM 1 , ACM 2 , ACF), have been tested in two cultivation cycles for their capacity to furnish P on ryegrass grown in pot, without and with mineral nitrogen supply (N-; N +; 112+112 days). In N-ACM 1 and ACF showed higher P (+5%) uptake compared to the chemical fertilizer (N-P-K). In N+ all compost showed higher P uptake in comparison to N-P-K (+7%), apart from ACV (-5%). Some compost may therefore represent a valuable source of P for plant nutrition in the medium-long term, leaving also appreciable level of potentially available-P in soil, oppositely to what showed following a phosphate chemical fertilization
15N e 13C nella valutazione dell’uso dell’azoto e della conservazione del carbonio da compost
No full textThe natural abundance of stable isotopes of nitrogen (15N) and carbon(13C) of four composts (ACV; ACMdig; ACF; ACM) applied at 10 and 20 Mg OM ha-1, was used to estimate the utilization of N in ryegrass and the variation of the soil carbon isotopic signature (13C‰) at the end of a cultivation cycle (112 days). ACMdig and ACF showed the greatest N use efficiency (15NRF: 9-16%), in agreement with their higher mineral-N. At the end of the test the 13C ‰ ranged between -25.39 and -25.55 (control vs. NPK); between -26.76 and -26.55 in ACV and ACMdig, while ACF and ACM were intermediate (-25.94; -26.06). The 13C ‰ in the various treatments was described by a linear relationship with CO2 emissions, highlighting a reduction in the carbon's storage capacity in the less stable products, being this influenced by the application level. The greater the application of not completely stable compost, the smaller is the C conserved in the soil
Fondamenti di chimica del suolo. Capitolo 8, adsorbimento e scambio.
No full textIl volume è organizzato in 13 capitoli che affrontano rigorosamente gli aspetti della formazione, delle componenti e dei principali processi chimici che avvengono nel sistema suolo-pianta. Il capitolo 8 è dedicato ai processi e ai meccanismi di adsorbimento e scambio ionico
Gestione della frazione organica dei rifiuti solidi urbani tramite digestione anaerobica e compostaggio: l’effetto sulla disponibilità del fosforo
No full textI rifiuti organici sottoposti a trattamento biologico possono rappresentare una fonte di fosforo (P) per le colture. Il trattamento integrato anaerobico-aerobico della FORSU è un’importante realtà in Italia, tuttavia la sua influenza sulla disponibilità potenziale del P è poco conosciuta. Nel presente articolo, due digestati anaerobici (DA) ed i rispettivi compost (ACM) sono stati analizzati per la stabilità biologica (OUR) e sottoposti a frazionamento del P-inorganico (Pi) tramite estrazione sequenziale (SCE), inoltre la disponibilità potenziale di P (P-Olsen) è stata valutata mediante incubazione in suolo. I risultati evidenziano che il compostaggio incrementa la stabilità biologica dei DA, necessaria per il corretto impiego in campo, e che poco influenza il frazionamento del P, che è risultato determinato principalmente dalle caratteristiche dei DA. Il frazionamento del Pi fornisce utili indicazioni relative alla potenziale disponibilità dell’elemento nel suolo
Changes in soil phenol oxidase activities due to long-term application of compost and mineral N in a walnut orchard
Full text linkPhenol oxidases (POs) are a group of soil extracellular oxidoreductase enzymes, which are involved in oxidative processes related to nutrient cycling. This class of enzymes has multiple functions at both the organism and ecosystem level and can trigger either positive or negative feedback loops between soil organisms and soil organic matter.
The purpose of this study was to evaluate: (i) whether PO activities have a trend different from those of microbial biomass and activity; and (ii) whether PO activities are enhanced or reduced by fertilizer application.
Soil samples were taken from plots in a 14-year-old experimental walnut orchard, subjected, since planting, to three fertilizer treatments: organic (compost) or mineral (urea) fertilization at the same rate of nitrogen application (100 kg N ha− 1), or left unfertilized. Soil samples were divided according to sampling depth (0–20 cm and 20–40 cm).
Results showed that the application of compost significantly increased C and N pools. qCO2 and DHD/Cext data indicated that the biota at 20–40 cm soil depth was more stressed or mainly composed of microorganisms with low substrate utilization efficiency. Phenol oxidase, tyrosinase, and catechol oxidase activities were significantly promoted in the surface layer by compost addition. In contrast, laccase activity showed a large increase in the deeper soil layer when supplied with mineral N, whereas compost addition led to increased activity in the surface layer. These findings suggest that soil phenol oxidases play a part in the determination of soil functionality, but they need to be investigated in greater depth in order to understand the mechanisms regulating their activities
Rotation and Fertilization Effects on Soil Quality and Yields in a Long Term Field Experiment
Full text linkUnderstanding the complex relationships among soil quality, crop productivity, and management practices would help to develop more sustainable agricultural production systems. In this study, we investigated the combined effects of crop rotations and fertilization treatments on soil quality and crop yield in a long term (about 50 years) field experiment. Crop rotations included continuous corn (Zea mays L.), a 2 year corn-wheat (Triticum aestivum L.) rotation, and a 9 year corn-wheat-corn-wheat-corn-wheat-alfalfa-alfalfa-alfalfa (Medicago sativa L.) rotation. Fertilization treatments included control, mineral fertilization with urea and triple superphosphate, and amendment with cattle manure. Crop rotations and fertilization treatments were combined in a factorial experimental design with two replications for each rotation and six replications for each fertilization treatment. The continuous corn and the corn-wheat rotations had negative effects on the main soil quality indicators considered (carbon (C) and nitrogen (N) pools, microbial biomass and activity).
On the contrary, the 9 year rotation had positive effects on soil organic carbon (+24%) and total nitrogen (+23%) but resulted in impoverished available P (5%). Positive effects on soil microbial biomass (+37% of microbial biomass C and +23% of microbial biomass N) and activity (+19%) were also observed. Soil amendment with manure built up soil organic carbon (+13%), increased nutrient content (+31% of extractable C and +19% of extractable N), including that of available P (+47%), and stimulated microbial growth (+34%) and activity (+8%). As compared to manure, mineral fertilization increased the soil nutrient content to a lesser extent. This study showed that the combined use of rotations, including legume forage crops, and soil amendment with manure may help preserve soil quality and crop productivity in the long term
SOIL: The vision to a global challenge
No full textMaintaining and improving the soil resource is crucial for the protection of the global environment, the sustainability issues, the human well-being, and the economic development. Soil is in fact a complex integrated system whose multitude of biotic and abiotic properties allows the provision of functions, which in turn deliver ecosystem services for human benefits.
The most widespread agrarian, forest and food production systems may have negative impacts on soil, thus exacerbating its degradation processes. There is an increasing awareness that improper use or poor soil management, together with the most recent events related to climate change, jeopardize the proper functioning of soils. The need to protect the soil resource is thus widely shared internationally. One of the major challenges in the new growth EU strategy is to accomplish food security and to promote sustainable agricultural development, achieving the climate neutrality by 2050. Given the crucial role of soil for human activities, the Soil Thematic Group of the Department of Agricultural and Food Sciences (DISTAL), Alma Mater Studiorum - University of Bologna (Italy), states its position identifying the main challenges for the future growth of EU in:
- The organic carbon loss;
- Bio-technologies for agro-waste conversion into eco-efficient bio-based products;
- Soil biodiversity: preservation and restoration;
- The agroecological systems for supporting the farm to fork and ecosystems and biodiversity policies;
- Towards a soil sustainable and suitable farm and food system;
- Forest soil restoration;
- Next generation policy instruments for soil conservation and carbon sequestration;
- Soil as energy resource for sustainable rural facilities;
- Novel methodologies and approaches to multi-criteria landscape analysis, monitoring and planning
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