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Agricultural residues are generated during the production and processing of agricultural crops. Under modern date palm plantation practices, field operations generate huge quantities of residues, which are discarded with little valorization. The date palm agro-industry produces significant amounts of waste. The accumulation of these residues can cause ecological damage to the oasis ecosystems. There is a lack of comprehensive data on long-term research studies that aim to assess the impact of date palm waste management practices. Composting and/or pyrolysis of date palm residues showed benefits for improving soil physical and chemical properties, particularly in sandy soils. This claim holds particular significance for arid and semi-arid regions, which are characterized by low fertility and are susceptible to soil degradation, accentuated by ongoing climate change. This review summarizes the existing literature concerning the valorization of date palm residues with regards to compost and pyrolysis processes, as well as the impact of their application on soil quality. Further research is required to assess the effects of using date palm residues for better soil amendment management. Research should focus on composting and biochar technologies for date palm residues and their application in arid and semi-arid regions to combat soil erosion and degradation. Increasing the beneficial uses of date palm residues could lead to sustainable and economic growth in dry areas. [ABSTRACT FROM AUTHOR]

For the first time, a complete physicochemical characterization of pruning residues from red grape varieties Cabernet Sauvignon (CSPR) and Malbec (MPR) from Mendoza, Argentina is reported. In addition, the extraction of lignocellulosic material by using an environmentally friendly methodology is reported, yielding 13.33 wt% for CSPR and 8.08 wt% for MPR. According to laser diffraction analysis (LD), the particle‐size distribution is similar for both varieties. Fourier transform‐infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning‐electron microscopy (SEM), optical microscopy (OM), and X‐rays diffraction (XRD) show the presence of lignin and cellulose in both samples. It may be concluded that vine shoots are an inexpensive and widely available source to obtain lignin and cellulose for multiple purposes, such as composites and blends. [ABSTRACT FROM AUTHOR]

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Agricultural residues are generated during the production and processing of agricultural crops. Under modern date palm plantation practices, field operations generate huge quantities of residues, which are discarded with little valorization. The date palm agro-industry produces significant amounts of waste. The accumulation of these residues can cause ecological damage to the oasis ecosystems. There is a lack of comprehensive data on long-term research studies that aim to assess the impact of date palm waste management practices. Composting and/or pyrolysis of date palm residues showed benefits for improving soil physical and chemical properties, particularly in sandy soils. This claim holds particular significance for arid and semi-arid regions, which are characterized by low fertility and are susceptible to soil degradation, accentuated by ongoing climate change. This review summarizes the existing literature concerning the valorization of date palm residues with regards to compost and pyrolysis processes, as well as the impact of their application on soil quality. Further research is required to assess the effects of using date palm residues for better soil amendment management. Research should focus on composting and biochar technologies for date palm residues and their application in arid and semi-arid regions to combat soil erosion and degradation. Increasing the beneficial uses of date palm residues could lead to sustainable and economic growth in dry areas.

Evaluating Global Warming Potential (GWP) in waste management scenarios is crucial, especially in light of the escalating global concern for climate change and the pivotal role that waste management plays in mitigating this crisis. This research examines the GWP of three distinct waste management scenarios, each with a unique approach: (1) open burning, a method involving direct combustion with a GWP of 1600.1 kg·CO2eq, chiefly attributed to direct emissions without any mitigation tactics; (2) energy recovery, which capitalizes on converting waste into energy, yielding a GWP of 1255.4 kg·CO2eq, the reduction resulting primarily from avoided heat production; and (3) pyrolysis, an advanced thermal decomposition process that remarkably registers a negative GWP of −1595.1 kg·CO2eq, mainly credited to the carbon sequestration capacity of biochar production and optimal energy conversion efficiency. These outcomes emphasize the ecological merits of waste management approaches that produce lower, or even better, negative GWP values. In particular, pyrolysis emerges as a powerful way of transforming waste management into a potential carbon sink, proving crucial for climate change counteraction. Nevertheless, for effective real-world deployment, the study highlights the importance of addressing technical, economic, and societal challenges, underscoring the need for holistic, interdisciplinary research. [ABSTRACT FROM AUTHOR]

Secondary lignocellulosic biomass has proved to be useful as an energy source through its oxidation by means of combustion processes. In accordance with the above, in this paper, we wanted to study the ash from urban pruning residues that are generated in cities in the Neotropics. Species such as Licania tomentosa, Azadirachta indica, Ficus benjamina, Terminalia catappa, Leucaena leucocephala, Prosopis juliflora and Pithecellobium dulce were selected because they have been previously studied and showed potential for thermal energy generation. These materials were calcined in an oxidizing atmosphere and characterized by X-ray diffraction and fluorescence, scanning electron microscopy with microchemistry, BET surface area, thermal gravimetric analysis, and differential scanning calorimetry. The pH and apparent density were also established. The results show high basicity materials (average pH 10), a behavior associated with the presence of chemical elements such as calcium, potassium, magnesium, chlorine, phosphorus, and sulfur. Structurally, these materials have a very significant amorphous fraction (between 49% and 74.5%), the dominant crystalline phases are calcite, arcanite, sylvite, and hydroxyapatite. These ashes have low surface area and do not exceed 13 m2/g. Two characteristic morphological aspects were observed in these ashes: a morphology of rounded grains where silicon content is highlighted, and lamellar morphologies where the presence of chlorine is highlighted. Thermally, these ashes show four significant mass loss events (400°C, 430°C, 680°C, and 920°C), causing mass losses that vary between 25% and 40%. Through this study, it was possible to establish that, from a chemical point of view, these ashes are less dangerous in comparison with those of a mineral coal that was used as a reference. However, they require additional treatments for their disposal due to their high basicity. Because of their composition, these ashes have the potential to be used in the ceramic and cement industries, and in the manufacture of fertilizers. [ABSTRACT FROM AUTHOR]

In Italy, the agricultural residues resulting from the pruning of vineyards represent a potential energy Source, in particular for the Veneto region, which is the second Italian region by vineyard area. This study is aimed at analysing the main physical and chemical characteristics of vine shoots from the annual pruning of vineyards. This for use them as wood chips in small-medium size power plants. International and European standards for the analysis of biofuels were used to determine the moisture content, heating value, ash content, micro and macro elemental and fibrous fraction (lignin, cellulose, hemicellulose and extractives). The samples were collected from three different vineyards in the Vicenza area. The varieties analysed were Chardonnay, Glera, and Merlot. For each variety, the three different components of vine shoots were compared: internode, node, and pith, to investigate in which part of the vine shoot the most significant accumulation of metallic elements deriving from plant protection products occurs. The results show significant differences among the energy parameters of the three varieties and three vine shoot components. In particular, the pith shows low heating value and high ash content, while higher energy values characterise the woody components. Analysis of the chemical elements showed a high content of Cu and Zn in the wood components, node, and internode, causing the high ash content found. In particular, Cu content exceeds the limits set by the reference standard. As regards the analysis of the fibrous fraction, a high content of extractives was found in the pith. These extractives could explain why the pith of the three varieties analysed, especially in Chardonnay, have lower heating value on dry basis (LHV0) values and high ash contents. On the contrary, the node and internode components have a higher cellulose, hemicellulose, and lignin content. Overall, the vine shoots analysed have characteristics suitable for possible energy use. However, according to EN ISO 17225-9:2021 standard, these can only be used as wood chips for industrial purposes in large power plants due to the high ash and Cu content. [ABSTRACT FROM AUTHOR]

In Italy the agricultural residues resulting from pruning of vineyards represent a potential energy resource, in particular for the Veneto region which is the second Italian region by vineyard area. This study is aimed at analyzing the main physical and chemical characteristics of vine shoots from the annual pruning of vineyards. This is for their possible use as wood chips in small-medium size power plants. International and European standards for the analysis of biofuels were used to determine the moisture content, heat value, ash content, micro and macro elemental and fibrous fraction (lignin, cellulose, hemicellulose and extractives). The samples were collected from three different vineyards in the Vicenza area. The varieties analyzed were Chardonnay, Glera and Merlot. For each variety, the three different components of vine shoots were compared: internode, node and pith, to investigate in which part of the vine shoot the greatest accumulation of metallic elements deriving from plant protection products occurs. The results show significant differences among the energy parameters of the three varieties and three vine shoot components. In particular, the pith shows low heat value and high ash content while the woody components are characterized by higher energy values. Analysis of the chemical elements showed a high content of Cu and Zn in the wood components, node and internode, causing the high ash content found. In particular, Cu content exceeds the limits set by the reference standard. As regards the analysis of the fibrous fraction, a high content of extractives was found in the pith. These extractives could be one of the explanations why the pith of the three varieties analyzed, especially in Chardonnay, have less lower heat value on dry basis (LHV0) values and high ash contents. On the contrary, the node and internode components have a higher content of cellulose, hemicellulose and lignin. Overall, the vine shoots analyzed have characteristics suitable for a possible energy use. However, due to the high ash and Cu content, according to EN ISO 17225-9:2021 standard these can only be used as wood chips for industrial purposes in large power plants.

No-tillage and soil mulching with pruning residues, applied in olive groves of the semi-arid Mediterranean environment, as erosion control practices still practice not fully studied. This study has evaluated the saturated hydraulic conductivity (Ksat), surface runoff (SR) and soil erosion (SL) under rainfall at plot scale throughout two years in four different management practices, total soil cover with a net (SP), mechanical tillage (MT) and mulching by vegetal residues at 3,5·103 and 17,5·103 kg ha−1 of dry matter (NTR350 and NTR1750), in an olive grove of Southern Italy. Ksat varied between 1.6 (MT) and 25.1 (NTR1750) mm/h. A clear reduction in runoff and soil losses was detected for the mulch-based practices when compared to MT, from 20 to 32% in the runoff coefficient and 75–80% in SL, with higher reductions in the NTR1750. This reduction in SL can be mainly explained by the reduction in SR and rain-splash, interrill and rill erosion, due to protection by mulch residues, which increased the vegetal cover and organic matter content of mulched plots. The vegetal cover was on average higher in SP (33%), NTR1750 (25%) and NTR350 (22%), and lower in MT (12%). The mean organic matter content of soil was 2.01%, 1.69%,1.34% and 0.82% for NTR1750, NTR350, SP and MT respectively.Overall, the results quantify the impact of soil mulching with pruning residues at different doses, which will provide guidelines to control and mitigate the hydrological response of clayey and steep soils in Mediterranean olive groves, analysing the associated environmental and economic benefits.

Backgrounds and aims: Litter protects the underlying soil, depending on litterfall and decomposition, but dynamics of the standing litter stock in agroforestry systems remain poorly understood. We aimed to unravel effects of litter quality, temporal patterns, microclimate, and a possible home-field advantage (HFA) on standing litter dynamics across a land-use gradient. Methods: We quantified litterfall, the standing litter stock, and microclimate during a year in (remnant) forest, cacao-based simple and complex agroforestry, cacao monocultures, and annual crops in a cacao producing area in Indonesia. We conducted a reciprocal litter transfer experiment, and tested decomposition rates of pruning residues. Standing litter stocks during the year were estimated from monthly litterfall and decomposition rates. Results: Variation in litter quality influenced decomposition rates more strongly than variation in microclimate or HFA. Lower litter quality in complex agroforestry and in the cacao monoculture decreased the decay rate compared to simple agroforestry systems; mean litter residence time was over a year. Mixing high- and low-quality material in pruning residues modified the decomposition rate, soil C and N changes, offering options for targeted management of soil protection and nutrient release. Conclusions: The seasonal patterns of litterfall and relatively slow decomposition rates supported permanence of the litter layer in all cacao production systems, protecting the underlying soil. [ABSTRACT FROM AUTHOR]

Turkey is among the leading countries in fruit production. Every year important amounts of pruning residues emerge from orchards. These residues have significant energy potential. There is a lack of study on the physical properties of pellet production from different orchard residues. Assessment of these residues is of enormous significance for the environment and economy. Pelleting is one of the methods of evaluating these low-density residues. Particle size and moisture content are the most important factors affecting pellet quality. The aim of this study is to evaluate the pruning residues such as olive, vineyard and pomegranate as biofuels. For this, pruning residues were pelleted in a pellet machine. Different moisture contents (10-12% and 14-16%) and three different particle sizes (2, 4 and 6 mm) were used in the experiments. The physical properties of pellets such as particle density, bulk density, durability, tensile strength and absorption resistance were defined. Besides, energy consumption values and pellet production capacity were measured. At the end of the experiments, depending on the material properties and moisture content, average pelleting machine pellet production capacity was measured as 23–83 kgh−1 and cylindrical pellets with an average diameter of 6 mm were produced. The particle density and bulk density of pellets were between 981–1338 kgm−3 and 521–793 kgm−3, respectively, and pellet densities were decreased with increasing moisture content. In addition, the relation between physical properties was analyzed by using the analysis of variance (ANOVA) method using by IBM SPSS 17 software. [ABSTRACT FROM AUTHOR]

Utilize agricultural residues from pruning brings many advantages including employment, social and economic benefit, rural development, natural forest protection, increased energy efficiency, and lower costs of raw material for the production of particleboard industry. In this study, the use of wood utilization of pruning residues from apple trees has been investigated by using chipping at the landing chipping methods (LCMs) and farm chipping methods (FCM). These methods were conducted on seven farms, totaling 9.2 ha. A time study was used to estimate operation time and cost. Transportation of chips from the study area to factories was done with semi-trailers, trucks, and pickup trucks. The residue yield was between 1.8 and 2.0 green ton per hectare. The maximum time was related to chipping and the collection of residues and the most delay was mechanical. The residues were collected, chipped, and transported to the particleboard factory at a cost between US$10.18 and US$19.46 per ton, and the profit rate between US$15.5 and US$24.8 per ton depending on chipping methods and secondary transport system. Cost and the total time of LCM were lower than the FCM, and also production rate of LCM was higher than the FCM; therefore, this method was more effective in processing residues from apple trees. Regression techniques showed that in LCM, the effect of diameter and age was significant on residue processing time and in FCM, the effect of diameter, age, residue density, and functional the area was significant in residue processing time.

Concentrated flow erosion in Mediterranean cultivated areas is considered a major process of land degradation. Rills and ephemeral gullies in a 6.4 ha olive orchard catchment located in an intensive commercial farm, which could represent a common degradation scenario in hilly areas, were measured and compared with the sediment loads at the outlet. Four GPS survey campaigns were carried out between March 2009 and March 2014, for periods with cumulative precipitation ranging between 728 and 121 mm. Chopped pruning residues were kept on the lanes during campaigns 2–4, whereas a grass cover crop was seeded in campaign 4. Rainfall, runoff and sediment loads were measured in a flume gauge station at the catchment outlet. The ratio of concentrated flow erosion to catchment sediment load varied between 1.0 and 35.0. Total concentrated flow erosion ranged between 25.0 and 0.1 t ha−1. Rill erosion was the dominant process on ephemeral gullies for three campaigns, with a mean contribution to the total concentrated flow erosion of 55%. Rills clearly followed tractor tracks along the most parallel lanes to the maximum slope. Therefore, a change in traffic direction would be helpful to reduce the connectivity, controlled by the spatial distribution of rows and lanes in the farm. Olive plantation distributions should prioritize hydrological criteria to adapt traffic patterns in olive farms, as long as the tractor manoeuvrability and risk of overturning are not adversely affected. Although the farmer only kept the cover crop for one campaign, it proved to be an efficient measure for interrupting rills along the lanes, whereas pruning residues were effective for the control of interrill erosion. On‐site application of pruning residues reduced their handling and transport costs, while increasing the soil fertility and soil cover. However, guidelines for the efficient application of pruning residues are still necessary in terms of residue rates and orientation. [ABSTRACT FROM AUTHOR]

The global need to transition to renewable and decentralized systems entails agricultural systems as producers of residual biomass. Avocado trees (Persea americana Mill.) are one of the main woody crops cultivated in Mexico, with over 150,000 hectares grown in the country. The aim of the present study is to evaluate the use of avocado pruning residues as an energy input, focusing on the revalorization of biomass and the generation of economic benefits for small producers in the region. For that purpose, we developed allometric equations to calculate biomass availability from pruning residues, evaluated their thermochemical properties, and proposed technological alternatives for their energy use. Two allometric equations for pruning residues as a function of tree height and crown diameter were obtained: one for light and minor maintenance pruning (R2 = 0.63) and one for rejuvenation pruning (R2 = 0.86). From these equations, we estimate the mean amount of biomass generated from light and rejuvenation pruning to be 42.7 and 25.1 kg per tree and year, respectively, which amounts to 1324 and 780 kg ha−1 DM (dry matter), with an energy potential of 26.2 and 15.4 GJ ha−1. The thermochemical analysis shows that a higher proportion of leaves generates a higher ash content, which reduces the quality of the residues as a fuel. Avocado pruning residues have high potential for energy use and could be implemented in the industrial and residential sectors, generating a complementary source of income for producers.

• Image analysis detected modifications of pruning residue particles after charring. • SEM showed nonporous surface on poultry litter particles after 550 °C pyrolysis. • Hyperspectral EDFM image highlighted cattle digestate biochar formed by semi-crystalline aggregates. • Emerging imaging techniques are effective for characterizing biochar properties. Biochar from agricultural biomasses and solid wastes represents a win-win solution for a rational waste management. Its sustainable usage requires the identification and standardization of biochar characteristics. The aim of this work was to identify the physical-chemical and spatial characteristics of biochars from pruning residues (PR), poultry litter (PL), and anaerobic cattle digestate (CD) at two pyrolysis temperatures (350 °C and 550 °C). The biochar characterization was carried out by applying emerging imaging techniques, 2D automated optical image analysis and hyperspectral enhanced dark-field microscopy (EDFM), and by SEM analysis. As predictable, the feedstock composition and the pyrolysis temperature strongly influence the physical structures of the biochar samples. Irrespective of charring temperature, PR biochar was mainly characterized by a broken and fragmented structure with an irregular and rough particle surface, completely different from the original PR wood cell. The EDFM imaging analysis evidenced the thermal degradation of PR vegetal products, composed primarily of hemicellulose, cellulose and lignin. On the contrary, small and regular particles with a smooth surface were produced by the PL pyrolysis, especially at 550 °C, due to the lower PL morphological homogeneity in comparison with the other biomasses. Finally, CD charring at both temperatures was characterized by changes in chemical composition, suggested by a lower pixel intensity. In conclusion, the emerging imaging techniques used in this study proved to be very effective in analyzing some properties of biochars, and can, therefore be considered as promising experimental strategies for detecting the feedstock and pyrolysis temperature of biochar. [ABSTRACT FROM AUTHOR]

Biomass occupies a very important place among renewable energy sources, and the residual biomass recovery chain represents a sector of fundamental importance. Our work focused on the production of pellets by pruning residues from two of the most important woody crops in Italy: hazelnut and olive groves. We found a higher value of bulk density for the hazelnut pellet (581.30 kg m−3 vs. 562.38 kg m−3) and a higher value of length for the olive pellet (16.66 mm vs. 10.47 mm). The percentages of durability were very similar (98%). The low heating value and ash content of hazelnut and olive were 17.21 MJ kg−1 and 3.1%, and 16.83 MJ kg−1 and 2.5%. A higher concentration of Cu, Pb, and Ni was observed in the hazelnut. The contrary was observed for the concentration of Zn. N content was 0.77% and 1.24% for the hazelnut and the olive, respectively. The concentration of S was 0.00% for both. The quality parameters that do not meet current standards could be improved by mixing these materials with different types of wood.

In the EU, bioenergy is by far the most significant renewable energy source and more than two thirds of biomass utilized for energy conversion consists of forestry and agricultural residues, such as fruit tree pruning. Although still underutilized, biomass from pruning is a relevant energy feedstock that does not generate additional demand for land, nor negative impact on the environment and biodiversity. On the other hand, previously shredded pruning left in the field may sustain agricultural processes and help provide beneficial ecological services. In the latter case, the most relevant result is the increase in soil organic carbon, an essential factor for improving soil quality and promoting climate regulation. As a result, a “dilemma” arises for farmers over two conflicting pruning management options: “pruning to energy” vs. “pruning to soil”, respectively. The present study, performed in the frame of the Horizon 2020 project “uP_running”, is offering a straightforward evaluation tool to assess weather biomass resulting from fruit tree pruning could be removed from the field and used as energy feedstock without compromising both soil quality and the provision of important ecosystem services.

Chile is the second largest global producer of blueberries, which are harvested in the south-central region. As a result of the exponential production growth, a large amount of lignocellulosic biomass is generated from pruning and left on the ground as waste. As an alternative to the current incineration practices and their negative air pollution effects, this study proposed value-added utilization of these agroindustry residues. The chemical compositions (cellulose, hemicellulose, lignin, extractives, and ash) of the pruning residues from blueberry branches and trunks were analyzed. The cellulose contents from the branches and trunks were similar at 52% and 51%, respectively. However, the X-ray diffraction analysis indicated important differences in their crystallinity index, with 52% and 84%, respectively. Compared with the cellulose obtained from the trunks, cellulose from the branches was less thermally stable, possibly due to the presence of residual lignin and hemicellulose. According to the results, it is expected that the agroindustrial residues from pruning of the Chilean blueberry bushes (branches and trunks) might be of use as a potential platform for bioproducts, such as cellulose materials in order to replace synthetic or unsustainable materials. [ABSTRACT FROM AUTHOR]

A model procedure for the sustainable management of plant biomass related to wine production, namely vine branches from agricultural practices in the vineyard and marcs remaining after grapes crushing, was devised. An artificial humification process was set up that could respond to the needs of environmental sustainability and could be a safe way to be reintroduce in the vineyard part of the organic matter previously exported, thus contributing to recover or maintain vineyard soil fertility. Two different strategies for composting were tested, namely a static pile, made by branches and marcs, and a pile that was fed twice a year alternatively with vine branches and grape marcs. The experimentation lasted 710 days, during which environmental parameters, i.e. temperature and rainfalls were monitored. Growth dynamics of the principal functional groups of microorganism were followed. A characterization of the composted material was obtained by measuring several parameters among which, pH, carbon, nitrogen, sulfur and heavy metals content. The characteristics of the produced compost fulfill the requirements prescribed by the Italian legislation regarding the use of compost as soil amendment. Germination tests demonstrated the absence of phytotoxicity and conversely evidenced a stimulating activity towards root development. [ABSTRACT FROM AUTHOR]

EN norms set the methods for determining the ash and volatile content in biomass. These establish the use of a muffle to heat the samples at temperatures of 550 °C and 900 °C respectively, with a minimum analysis time of 4 h as standard method. The objective of this work was to reduce significantly the analysis times, making very short heating periods using a thermogravimetric scale (TGA), and to apply an equation to the residual weight to obtain the weight of ash, volatiles and fixed carbon in biomass samples. We analyzed the factors: the temperature ramp, atmosphere and airflow in the determination. In this work new validated methods were developed with an analysis time of 10–20 min. [ABSTRACT FROM AUTHOR]

Abstract: Erosion is one of the main environmental problems affecting soil in olive orchards. The present research aims to study the protection effect against soil erosion of three different managements of pruning residues in olive orchard. The investigation was carried out in an olive orchard with a total production of 0.39 kg m−2 of dry weight of pruning residues every 2 years. These pruning were chopped and scattered in 2 m‐wide strips through three different managements. Management A, with densities of 1.56 kg m−2 distributed in all the inter‐rows of olive orchard. Management B, with densities of 3.12 kg m−2 distributed on half of the inter‐rows of olive orchard. And management C, with densities of 3.12 kg m−2 distributed on half of the inter‐rows of olive orchard, alternating this application every 2 years with another half of the inter‐rows. The influence of the residues on soil protection has been measured through the evolution of three parameters of the residues over 4 years: residues mass degradation, soil cover percentage, and spatial distribution. The results of the study have shown that the management C is the one that best protects the soil from erosion in olive orchard. This management maintains a protecting cover over inter‐rows of olive orchard above 40%, maintaining homogeneity of the cover twice as much as the management in which pruning residues are left in all inter‐rows. [ABSTRACT FROM AUTHOR]

Woody crops such as orchards and olive groves require annual pruning operations, which leave abundant residues on the ground. These must be removed both for disease control and for facilitating the following tending activities. The resulting biomass can be managed as a waste or a by-product, in both cases incurring in a cost for farmers. A harvester prototype for collecting and comminuting apple pruning residues was tested and compared to a traditional mulcher. In particular, the study aimed at: 1) quantifying productivity and costs of the two systems, 2) evaluating the possible influence of apple variety, tree age and machine type on the productivity per hectare, and 3) estimating and comparing the energy balance of the two working options. The mulcher achieved a productivity of 0.41 ha SMH −1 against an average 0.27 ha SMH −1 of the harvester. Age of trees significantly influenced the productivity of both machines, with operative speed 42% higher in younger plantations. The cost of the operation added up to 137.5 € ha −1 and 275.2 € ha −1 , respectively for the mulcher and the harvester. But the latter also produced 0.77 t dry matter ha −1 of biomass fuel suitable for in-farm use, whose value can cover most or the total of harvest costs. Accordingly, the energetic inputs amounted to 0.59 GJ ha −1 and 1.06 GJ ha −1 respectively for the mulcher and the harvester, while the recovered biomass provided an output of 6.30 GJ ha −1 for the latter system, resulting in a positive energy ratio (5:1). [ABSTRACT FROM AUTHOR]

Focusing on the reuse of the energy and aiming at the thermal and kinetic characterization of sewage sludge and its mixture, with pruning residues (50 mass%), the thermogravimetry was used. The kinetic study was elaborated from the local isoconversional integral method in heating rates 10.0, 20.0 and 30.0 °C min at a temperature ranging from 219 to 386 °C at nitrogen atmosphere, in a flow of 100 mL min. The average activation energy of sewage sludge sample revealed the value of 219 kJ mol and that of the mixture 161 kJ mol, supporting the incorporation of pruning residues in the sewage sludge. During the degradation process, a remarkable increase in activation energy was noticed that ranged from 20 to 70% conversion in the sewage sludge sample, and regarding the mixture, an almost linear behavior was observed during the decomposition reaction. There was no evidence of kinetic compensation effect in the performed studies. The evaluation of the thermal characteristics, as well as the kinetic study of the degradation of sewage sludge and its mixture with pruning residues, can lead to important insights and contribute to a better use of energy regarding the environmental issues. [ABSTRACT FROM AUTHOR]

When olive groves are cultivated on clayey soils with steep gradients, as in many Mediterranean areas, reducing the runoff and soil erosion rates by adopting proper soil management practices is imperative. A soil cover by pruning residues may represent an alternative to the commonly adopted mechanical tillage. This study evaluates the water infiltration rates and surface runoff volumes in a steep and clayey olive grove of Southern Italy. These hydrological variables are measured at the plot scale under four soil management practices (mechanical tillage, total artificial protection of soil and soil cover with two different rates of vegetal residues). The measurements have been carried out using a rainfall simulator under dry (undisturbed) and wet (that is, on soils disturbed by intense rainfall) conditions. The mechanical tillage leads to lower water infiltration rates and higher runoff production. The retention of a soil cover by vegetal residues (in the range 3.5⁻17.5 tons/ha of dry matter) reduces the runoff rate on average by 30%, mainly because of the increased soil infiltration rates (over 100%, compared to mechanical tillage). After soil disturbance due to antecedent rainfall, the runoff generation capacity of a soil disturbed by a heavy precipitation significantly increased compared to undisturbed soils because of the decrease in soil infiltration rates. Overall, the retention of vegetal residues over the soil may be advisable to reduce surface runoff generation rates, particularly for saturated soils.

The spatial characterization of soil protection is important for preventing land degradation. Mulch covers of pruning residues are increasingly used by farmers, but little is known regarding their spatial variability. Thus, field research was conducted in a 14·7-ha traditional olive grove located in Córdoba (Spain), to evaluate the variability of the initial density of pruning (Dpo), tree crown volume ( V) and N content in residues (Np). Dry pruning weight and Np were characterized in 49 and 47 samples, respectively, covering approximately half of the area. V was measured in 178 locations covering all of the study area. The spatial continuity of these variables was described by spherical variograms. Geostatistical simulation algorithms were employed. One hundred realizations were made for Np through direct sequential simulation. Because the association with V was large ( rxy = 0·72, p-value < 0·001), we ran a geostatistical cosimulation algorithm to obtain 100 maps of Dpo. The final density of pruning (FDp) was determined by applying a residue decomposition model for a 2-year period to pairs of previously simulated maps of Np and Dpo. After setting soil protection cut-off values for FDp, the soil protection probability was calculated for pruning strips of 2 and 4 m width. Finally, we converted the probability maps into binary maps and classified the farm into protected, unprotected and uncertain zones. V provided valuable input to evaluate soil protection. The application of stochastic simulations coupled with a decomposition model was useful to identify critical areas. This methodology can be easily applied to other crops. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Agricultural residue could become a potential biomass source for energy production because it is available every year in areas accessible to tractors and vehicles. The aim of this work was to quantify the biomass available and its fuel characteristics, considering pruning residue from management of five main vine varieties planted in northwest Italy (barbera, dolcetto, cortese, cabernet sauvignon, and moscato) for a period of 15 years (from 2000 to 2014). Throughout the test period, pruning residue production ranged between 0.45 and 1.34 kg (1850–5360 kg ha −1 ) per plant. The average higher heating value of the five vine varieties tested ranged from 17.92 to 18.02 MJ kg −1 , whereas the lower calorific value ranged between 7.34 and 7.96 MJ kg −1 . The average ash content was approximately 3.85%. No statistical difference in biofuel characteristics was found between the vine varieties considered. This study highlights the high potential of vineyard pruning residue as a biofuel for energy production. In contrast, it is of considerable importance to know that biomass production can vary considerably between vine varieties and between years. This latter aspect is very important because, according to reference years, it is possible to under- or overestimate biomass production. [ABSTRACT FROM AUTHOR]

Adding some pruning residues to the soil could result on phytotoxicity due to the presence of polyphenols. Pyrolysis of those residues could lead to a product with less polyphenols and a potential to be used as soil amendment. Soil biological properties, and, in particular soil enzyme activities have often been as indicators of soil quality. We tested phytotoxicity, using a germination test, and soil biological properties, namely soil microbial biomass C and soil microbial biomass N, soil basal respiration and several soil enzymes (β-glucosidase, β-glucosaminidase and phosphomonoesterase) in a soil amended with pruning residues and with biochars prepared at 300 °C and 500 °C from those residues. Moreover, both biochar and pruning residues were divided into finer (<2 mm, but mostly dust) and coarser (>2 mm) particles and we studied the effect of adding two different doses of amendments (1 and 3%). Biochar resulted in an increase in the germination index of tomato and lettuce seeds in comparison to pruning residues, while no difference was found for the other plant species tested (watercress and lettuce). Pruning residues showed phytototicity in the tomato germination test. In general, both, pruning residues and the use of amendments with finer size particle resulted in an increase in soil enzyme activity. Our results indicate that soil enzymes are not responsive to the presence of polyphenols and could not be used as suitable indicators of soil quality in soils amended with residues containing polyphenols, while germination tests are more suitable to detect the presence of these toxic compounds. [ABSTRACT FROM AUTHOR]

The composting process produces and emits hundreds of different gases. Volatile organic compounds (VOCs) can provide information about progress of composting process. This paper is focused on the qualitative and quantitative relationships between compost age, as sign of compost maturity, electronic-nose (e-nose) patterns and composition of compost and composting gas at an industrial scale plant. Gas and compost samples were taken at different depths from composting windrows of different ages. Temperature, classical chemical parameters, O 2 , CO, combustible gases, VOCs and e-nose profiles were determined and related using principal component analysis (PCA). Factor analysis carried out to a data set including compost physical–chemical properties, pile pore gas composition and composting time led to few factors, each one grouping together standard composting parameters in an easy to understand way. PCA obtained from e-nose profiles allowed the classifying of piles, their aerobic–anaerobic condition, and a rough estimation of the composting time. That would allow for immediate and in-situ assessment of compost quality and maturity by using an on-line e-nose. The e-nose patterns required only 3–4 sensor signals to account for a great percentage (97–98%) of data variance. The achieved patterns both from compost (chemical analysis) and gas (e-nose analysis) samples are robust despite the high variability in feedstock characteristics (3 different materials), composting conditions and long composting time. GC–MS chromatograms supported the patterns. [ABSTRACT FROM AUTHOR]

The utilization of organic wastes to improve soils or for growth media components in local farms and nurseries can reduce the environmental pollution linked to waste disposal while increasing the sustainability of crop production. This approach could be applied to waste products generated from the production of guacamole (an emerging activity in the avocado production areas in mainland Spain), where appropriate treatment of this oily and doughy waste product has not been previously reported. The aim of this work is to study the feasibility of co-composting guacamole production residues (GR) with garden pruning waste (PW) as bulking agent, and the possible use of the compost produced depending on its quality. A windrow composting trial using three GR:PW ratios, 2:1, 1:2, and 1:7 was carried out. Temperature, moisture, organic matter, and C/N ratio were used to follow the evolution of the composting process during 7 months. After an additional 3-month curing period, composts were sieved to less than 10 mm and a set of European quality criteria was used to assess compost quality and intended use. In general, the 3 composting mixtures followed the classical process evolution, with minor differences among them. The 1:2 GR:PW ratio appeared most adequate for combining better process evolution and maximum GR ratio. Except for their high pH that limits their use as growing media component in some particular cases, the obtained composts fulfilled the more stringent European standards for commercial composts. Self-heating tests confirmed the high stability of the composts produced. The germination of cress by the direct contact method was satisfactory for composts GR:PW 1:2 and 1:7, showing no signs of toxicity. Avocado seedlings planted in substrates containing 67% of the GR:PW composts exhibited greater plant growth than those in the control treatment, and with no signs of phytotoxicity. The results open an interesting opportunity for the sustainable treatment of avocado fruit by-products derived from guacamole and avocado oil processing. [ABSTRACT FROM AUTHOR]

The addition of organic matter in the form of compost improves overall physical, chemical and biological properties of soils but, to be really sustainable, the composting process should be carried out using the by-products available in situ. Two different soils of a Mediterranean olive orchard, one managed traditionally (NAS) and the other amended with compost (AS), were investigated in a two-year experiment. Increases in total organic matter, total nitrogen and pH, were detected in AS if compared to NAS. Significant increases in total and specific microbial counts were observed in AS, with a clear amelioration of microbiological soil quality. The results demonstrated that soil amendment using compost deriving from olive mill by-products can be an important agricultural practice for supporting and stimulating soil microorganisms and, at the same time, for re-using these byproducts, so avoiding their negative environmental impact.

The global need to transition to renewable and decentralized systems entails agricultural systems as producers of residual biomass. Avocado trees (Persea americana Mill.) are one of the main woody crops cultivated in Mexico, with over 150,000 hectares grown in the country. The aim of the present study is to evaluate the use of avocado pruning residues as an energy input, focusing on the revalorization of biomass and the generation of economic benefits for small producers in the region. For that purpose, we developed allometric equations to calculate biomass availability from pruning residues, evaluated their thermochemical properties, and proposed technological alternatives for their energy use. Two allometric equations for pruning residues as a function of tree height and crown diameter were obtained: one for light and minor maintenance pruning (R2 = 0.63) and one for rejuvenation pruning (R2 = 0.86). From these equations, we estimate the mean amount of biomass generated from light and rejuvenation pruning to be 42.7 and 25.1 kg per tree and year, respectively, which amounts to 1324 and 780 kg ha−1 DM (dry matter), with an energy potential of 26.2 and 15.4 GJ ha−1. The thermochemical analysis shows that a higher proportion of leaves generates a higher ash content, which reduces the quality of the residues as a fuel. Avocado pruning residues have high potential for energy use and could be implemented in the industrial and residential sectors, generating a complementary source of income for producers. [ABSTRACT FROM AUTHOR]

Contemporary technologies of fruit and vine production imply conducting intensive plantation pruning, and so significant amount of biomass appear with ecological and energetic importance. Thermal energy use of biomass residues as pruning is important from the point of view of environmental protection, the closed cycle of production and emission and consumption of emission CO2. Remains of pruning the orchards are burden that hinders the implementation of agricultural practices so that their removal is necessary. Limited reserves of fossil fuels and pollution of the environment imposes the necessity of finding alternative and renewable sources of energy while reducing environmental pollution. Very current problem is to define the optimal technical solutions and technologies for utilization of machine pruning fruit trees and vines, you know increases the energy efficiency of production. Outdated technology, extensive production and disposal of inefficient energy in our country collecting, preparing and using plants remains is not enough application. A prerequisite for the study of the economic feasibility of using pruning remains present data on the quantity, energy potential, workmanship, transport ability, price, convenience for storage, preservation and combustion. The most important starting point for this research is defining energy potential pruning residues annually. The Republic of Serbia has approximately 600,000 t wood biomass from fruit and grape plantations. Modern burning methods of wood biomass, like different types of wood pellets or classic firewood, enable highly efficient usage of energy; have minimum emissions CO2 of harmful substances and comfortable heating in domestic. High investment expenses, making subventions from public and government sources indispensable, hinder their introduction. [ABSTRACT FROM AUTHOR]

Abstract: The application of organic materials to land is a common practice in sustainable agriculture. The current availability of several types of pruners and choppers on the market has boosted the use of these types of residues as plant cover. Applying these types of residues increases the content of organic matter in the soil, which is very positive for the fertility of the soil and agricultural biodiversity. The latter should be taken into account in ecological olive groves where fertilisation programmes are highly limited. However, no quantitative information is available to provide farmers with a precise assessment. Experiments were conducted over a period of two agricultural years (2009/10 and 2010/11). Treatments consisted of pruning applications to fine (<8cm in diameter) and thick (>8cm in diameter) in the amounts indicated, I=2.65kgm−2 fine; II=2.65kgm−2 fine+1.12kgm−2 thick; III=5.30kgm−2 fine; IV=5.30kgm−2 fine+2.24kgm−2 thick; and a control of spontaneous weeds. The greatest loss of residue mass was recorded at the beginning of the sampling period. The estimated biomass loss in the first six months represented 37–50% of the total. After 704 days of decomposition, the soil maintained cover percentages of 62, 76, 74 and 88% for treatments I, II, III and IV, respectively. The various treatments applied to pruning residues have been more effective at increasing the levels of soil organic matter (SOM) than spontaneous cover. SOM values on the surface (0–5cm) rose by 0.86, 1.04, 1.28 and 1.52% for treatments I, II, III and IV in regard to the control treatment, maintaining this improvement in fertility at a depth of 0–20cm, where SOM increased by 0.43, 0.46, 0.84 and 0.47% for treatments I, II, III and IV, respectively, in regard to the control. Considering all the soil sampled, the largest increase in SOM in regard to the initial content of the soil was achieved by treatment III, which contained the largest amount of fine residues, with 0.63%, compared to increases of 0.33, 0.29, 0.36 and 0.10% for treatments I, II, IV and spontaneous weeds, respectively. [Copyright &y& Elsevier]

This paper analyses both the processes of adoption and diffusion of the practice of using the chopped residues of pruning as mulch in the olive orchards of the Southern Spanish province of Granada, one of the major olive-producing areas in the world. Many olive groves in the area are located on steep areas where the risk of soil erosion is high. A majority of farmers have adopted no tillage, as an alternative to traditional tillage, combined with either vegetation soil covers or, more frequently, using the chopped pruning residues as mulch. The data used comes from a survey carried out in 2005 to 215 olive farmers. From farmers’ responses we estimate a binomial probit model to identify some socio-economic and institutional factors related to the decision to use the practice of mulching on a regular basis. We also estimate several diffusion models that describe the spatial and temporal spread of mulching among farmers. Our results show that mulching using the pruning residues is adopted by 43% of the surveyed farmers. The diffusion process of this practice has been very intense since the middle nineties, and seems to have been based on the interactions among farmers in the area of study rather than in other external source of information. Some of the relevant identified factors that affect the probability of adoption of this practice are farmer’s experience, the level of soil degradation in the farm or the continuity of farming by some relative. [Copyright &y& Elsevier]

Decentralized power plants fueled with biogas from organic waste are a keystone for large waste producers responsible for their waste management to reduce the impact of waste generation and poor management, especially in the urban centers, alongside bioenergy and other value-added products generation. This work presents an assessment framework for the characterization quantification and assessment of the biogas potential using theoretical and lab-scale methodologies to evaluate the technical and economic bioelectricity potential from biogas using the organic residues and effluents produced in the main USP campus. The yearly costs to transport and dispose of these residues are around US$ 3,253,716.25, and the electricity consumption is about 8.6 million US$/y. As a large generator, USP is responsible for its residue management, and reduce its generation by the local use to produce bioelectricity is a feasible option. The results show a biogas potential up to 2,363,405.15 m3, allowing for a bioelectricity generation of up to 4454 MWh/y. A potential to produce 3081.131 tones of dry biofertilizer was also estimated. The wasted resource could currently supply up to 5.6% of the Campus's electricity demand, with an investment of around US$ 1.5 million and a payback range between 3.64 and 7.5 years. • Waste management is a problem for large generators, as the University of São Paulo. • Biogas is a feasible solution to organic waste but still in development in Brazil. • Robust methods were applied to estimate the biogas potential for a relevant case. • The bioelectricity potential of the University was estimated at up to 4454 MWh/y. • The avoided electricity costs can reach 484,626 US$/y and a payback of 3.64 years. [ABSTRACT FROM AUTHOR]

During the seasons 2003/04, 2004/05 and 2005/06, a study was made of the evolution of runoff as well as soil and available P and K losses in the sediment carried away in a conventional till system—that most used at the present time—and in a no till system with added pruning remains in an olive grove of the picual variety located in Torredonjimeno (Jaén, Spain). A group of microplots for sediment collection in a randomized complete block design was established. The samples were collected in the field after each storm. In the study period, a total of 21 storms were recorded, with a precipitation of 450 mm in 2003/04, 179 mm in 2004/05 and 388 mm in 2005/06. The erosivity of the rainfall was characterized and the cover percentage in the plots throughout the time was determined. The establishment of pruning remains reduced soil loss with respect to conventional tillage (CT) in the 3 years (72%). Likewise, the available P loss greatly declined in the study (46.4%) under conservation agriculture. The reduction in available K loss (72.4%) was much greater than that of available P. The close relationship between both variables and sediment production also stands out. Runoff was the parameter on which the pruning remains had the least influence with only an 11% average reduction. [ABSTRACT FROM AUTHOR]