This study delves into the innovative application of a novel bacterial and enzyme mixture alone or combined with aeration in mitigating emissions from pig slurry storage and explores their impacts on ...the methane (CH4), carbon dioxide (CO2), and ammonia (NH3) emissions from stored pig slurry. A dynamic chamber was used in this research to assess the efficacy of the treatments. Biological additives (HIPO-PURÍN) of specific microbial strains were tested (a mixture ofof Bacillus subtilis, Bacillus megaterium, Bacillus licheniformis, Bacillus amyloliquefacien, and Bacillus thuringiensis) alone and combined with an aeration system (OXI-FUCH). Controlled experiments simulated storage conditions, where emissions of ammonia, methane, and carbon dioxide were measured. By analyzing the results statistically, the treatment with HIPO-PURÍN demonstrated a significant reduction in CH4 emissions by 67% and CO2 emissions by 60% with the use of biological additives, which was increased to 99% and 87%, respectively, when combined with OXI-FUCH aeration, compared to untreated slurry. Ammonia emissions were substantially reduced by 90% with biological additives alone and by 76% when combined with aeration. The study was driven by the need to develop sustainable solutions for livestock waste management, particularly in reducing emissions from pig slurry. It introduces techniques that significantly lower greenhouse gases, aligning with circular economy goals and setting a new standard for sustainable agriculture. Furthermore, there is a need to validate that farmers can independently manage pig slurry using simple and effective treatments techniques with profound environmental benefits, encouraging broader adoption of climate-conscious practices.
•Meta-analysis to assess effects of crop diversification and management on soil and yield.•Intercropping associated with increases in soil organic C and N.•No overall negative effect of intercropping ...on tree crop yield.•Temperature tends to decrease the response of crop yield, while precipitation tends to increase it.•The best combination for high crop yields, SOC, N and P is the adoption of annual alley crops, minimum tillage and organic fertilization.
A meta-analysis specially based on tree crops was conducted to evaluate the changes in soil organic carbon (SOC), soil N and P, and crop yield in a Mediterranean climate, which are affected by: (i) management practices (crop diversification, tillage, fertilization); (ii) environmental characteristics, such as soil clay and climatic variables; and (iii) study length. The aim of this study was to assess the benefits of crop diversification, conservation tillage (minimum tillage/no-tillage) and organic fertilization as alternatives to intensive conventional mono-cropping in field studies. All the diversified systems and conservation tillage systems and the use of organic fertilizers induced positive effects on SOC. The highest response in SOC was achieved by the growth of permanent crops in the alleys. Soil N showed a similar trend to that of SOC, but the effect of no-tillage was not significant compared to conventional tillage. No significant effect was observed in soil P except for the cultivation of permanent crops in the alleys, which had a negative effect. No effect was observed in tree crop yield due to the growth of alley crops, conservation tillage or organic fertilization. However, the response of crop yield was related to the specific climatic conditions of each region, with possible negative effects in warm and dry areas. Overall, the use of intercropping, conservation tillage and organic fertilization led to improvements in soil quality and fertility and maintenance of a ground cover that can protect soil. However, to avoid possible negative effects on soil P and N availability, the growth of annual alley crops with minimum tillage is suggested instead of permanent crops with no-tillage, especially in dry and warm areas. Our results also suggested that the soil properties evaluated were not the main drivers of long-term yield variability.
There are many enclaves in the Mediterranean basin with soils contaminated with heavy metal(loid)s, most of these in natural areas of great beauty that have suffered the consequences of industrial ...and mining activity for years. These soils pose a risk to human and animal health due to the transfer of metal(loid)s condemning these areas to isolation. The rehabilitation by means of phytoremediation is one of the most used techniques, but phytoremediation must be part of a comprehensive strategy of steps that guide owners and administrations in the recovery of ecosystem services. An easily replicable decision-making methodology is defined, considering the initial conditions, the preferences of the decision makers or typologies from among six possibilities and the different models of use, typified in 13 categories. As a result, a landscape is obtained that integrates phytostabilization and areas with recreational and/or educational uses. Two case studies from the southeast of Spain are presented as validation, a deposit of mining sludge residues and the channel of a river contaminated by industrial discharges. Both enclaves are included in the tourist and cultural offer of their area, thus achieving an environmental and socioeconomic benefit and have been visited by more than 1000 people in a two-year period.
Several sequential extraction procedures are widely applied for metals chemical fractionation in the literature. However, their limitations to be used in different soils and metals have not been ...discussed in detail. This study compares two of the most commonly used extraction methods for metals chemical fractionation: Tessier and BCR. The objectives were to i) assess the differences between concentrations of metals extracted in each fraction by both Tessier and BCR procedures; ii) elucidate if soil properties affected the extraction ability of each fraction from both procedures; and iii) evaluate how land use contributes to different chemical metal distribution. Results indicated that both methods provide similar results when were applied to the same soil, since non-significant differences were found in metal concentrations between both methods at each fraction. Conversely, when we compared among land uses, significant differences were found in the metal concentration between both methods, especially between agricultural/urban/industrial against forest soil. Redundancy analysis showed that in carbonate-rich soils, BCR extraction method could cover up the real concentration of exchangeable metals with those bound to the carbonate phase, being the Tessier method the most suitable one for this kind of soils. Therefore, although sequential extraction is a useful tool to understand the distribution of metals in soil, the method used must be selected according to the land use and specific soil characteristics, taking into account at least, soil carbonate content.
•Sequential extraction is an useful tool to stablish differences in metal distribution among land uses.•Metal fractionation among land uses depends on the metal concentration.•BCR method can cover up the real behaviour of the exchangeable fraction in calcareous soils.
Mining operations in northern Chile are responsible for numerous mine tailings deposits, which may represent a risk to human health and the environment. This study evaluated the phytoremediation ...potential of three plant species (Prosopis tamarugo, Schinus molle and Atriplex nummularia) to remediate copper mine tailings in northern Chile. To improve the characteristics of the tailing, three treatments based on arbuscular mycorrhizal fungi and organic and inorganic amendments were applied. Plant roots and shoots and the associated tailings samples were collected and analyzed for total metal concentrations of Cu, Mn, Fe, Pb, Zn and Cd. Bioconcentration Factor (BCF) and Translocation Factor (TF) were estimated to evaluate the plant species potential for phytoremediation. The results show that A. nummularia presents high TF values on untreated tailings for Pb and Zn; on tailings treated with CaCO3/compost for Mn, Fe, Pb and Zn, and on tailings treated with CaCO3/compost/mycorrhizae only for Zn. P. tamarugo presents high TF values on the untreated tailings for Pb and Zn; and on tailings treated with CaCO3/compost for Mn. S. molle presents high TF values on untreated tailings for Cu, Mn, Pb and Zn; on the tailing treated with CaCO3/compost for Mn and Zn, and on the tailing treated with CaCO3/compost/mycorrhizae for Mn and Pb. High TF values show that the plants studied under the specific characteristics of the treated or untreated tailings, present the potential of being used for phytoextraction. Regarding the BCF, the experiments showed values lower than 1 for all the metals, except for Cd, which for A. nummularia developed in the amended tailing, presented potential characteristics of a hyperaccumulator. This metal even had in general BCF values higher than 1 and TF lower than 1, which shows the potential of the three evaluated species as phytostabilizers for Cd. Regarding the effect of the amendments, the untreated tailing presented lower removal efficiency than the tailings treated with CaCO3/compost (T1) and CaCO3/compost/mycorrhizae (T2). On the other hand, no significant difference was found between treatments T1 and T2.
•Three native plant species were evaluated to remediate copper mine tailings.•AMF, compost and CaCO3 were added to improve the characteristics of the tailing.•Nummularia was found to be an accumulator of Mn, Pb and Zn.•S. molle showed characteristics of an accumulator of Cu, Mn, Pb, and Zn.
•Two legume-vegetable multiple cropping systems were compared to monocrops under two management practices.•Cowpea crop improved soil organic carbon and fertility in the subsequent broccoli ...crop.•Available phosphorus was directly linked to increases in organic carbon, nitrogen and soil aggregation.•Organic practice was related to improvements in soil structure and crop yield in the broccoli crop.•Conventional practice was related to carbon and nitrogen pools in the broccoli crop.
Including legumes in rotation systems may be regarded as a sustainable way to improve soil quality and fertility for subsequent crops. Improvements in soil quality depend on inherent soil properties, climatic conditions, adopted management practices, type of fertilization (organic, chemical, legumes or biological). Hence, the aim of this study was to compare the effect of two legume species (cowpea and fava bean) on soil organic carbon (SOC), total nitrogen (Nt), NO3−, NH4+, available P, soil aggregate stability and the subsequent yields of two vegetable crops (broccoli and melon) grown under conventional or organic systems after two multiple cropping cycles. A comparison of a broccoli monoculture, broccoli grown after cowpea (multiple cropping), a melon monoculture and melon grown after fava bean (multiple cropping) showed that the broccoli/ cowpea double cropping was significantly more effective for increasing SOC and Nt than melon/fava bean double cropping. For the cowpea/broccoli multiple cropping, conventional management contributed to increasing SOC and Nt, while organic management increased available P, aggregate stability and crop yield, although this effect was cultivar dependent. The effect of management practice was not significant for the fava bean/melon except as regard crop yield, the melon yield being greater than monocrop under conventional management. Thus, the use of cowpea in multiple cropping was better for increasing SOC, soil fertility and crop yield of the subsequent crop than the use of fava bean, probably due to rhizodeposition processes. Hence, this crop could regarded as a viable alternative for sustainable crop production under semi-arid conditions.
Water scarcity in arid and semiarid regions poses problems for agricultural systems, awakening special interest in the development of deficit irrigation strategies to improve water conservation. ...Toward this purpose, farmers and technicians must monitor soil water and soluble nutrient contents in real time using simple, rapid and economical techniques through time and space. Thus, this study aimed to achieve the following: (i) create a model that predicts water and soluble nutrient contents in soil profiles using electrical resistivity tomography (ERT); and (ii) apply the model to different woody crops under different irrigation regimes (full irrigation and regulated deficit irrigation (RDI)) to assess the efficiency of the model. Simple nonlinear regression analysis was carried out on water content and on different ion contents using electrical resistivity data as the dependent variable. A predictive model for soil water content was calibrated and validated with the datasets based on exponential decay of a three-parameter equation. Nonetheless, no accurate model was achieved to predict any soluble nutrient. Electrical resistivity images were replaced by soil water images after application of the predictive model for all studied crops. They showed that under RDI situations, soil profiles became drier at depth while plant roots seemed to uptake more water, contributing to reductions in soil water content by the creation of desiccation bulbs. Therefore, the use of ERT combined with application of the validated predictive model could be a sustainable strategy to monitor soil water evolution in soil profiles under irrigated fields, facilitating land irrigation management.
Creation of Technosols by use of different materials can be a sustainable strategy to reclaim mine tailings spread on the environment. A proper selection of materials is critical to efficiently ...contribute to soil creation, with development of soil structure, organic matter stabilization and stimulation of microbial growth. For this purpose, a 90days incubation experiment was designed with biochars derived from different feedstocks, added to tailings alone or in combination with marble waste (MaW). We aimed to assess the effects of the different materials on the evolution of C and N contents and pools, greenhouse gas (GHG) emissions, aggregate stability, and microbial biomass and activity. Results showed that carbonates provided by MaW increased pH around the target value of 8, with significant decrease in salinity by precipitation of soluble salts. Organic C and total N remained stable during the incubation, with high recalcitrant indices. Labile and soluble C and N pools were low in Technosols, with no differences with unamended tailings at the end of incubation. All biochars increased aggregate stability with regard to control by ~40%, with no effect of addition of MaW. Biochars significantly increased microbial biomass C during the first 7days of incubation; however, from this date, there were no significant differences with unamended tailings. The β-glucosidase activity was below detection limit in all samples, while arylesterase activity increased in biochar-amended samples favored by increases in pH. CO2 emissions were not significantly affected by any amendment, while N2O emissions increased with the addition of biochars with lower recalcitrance. CH4 emissions decreased in all Technosols receiving biochar. Thus, the combined use of biochar and MaW contributed to soil C sequestration and improved soil structure. However, labile sources of organic compounds would be needed to stimulate microbial populations in the Technosols.
•Biochars increased aggregate stability and recalcitrant soil C and N content.•Labile organic matter was too low to stimulate microbial biomass and activity.•Marble waste increased pH and so decreased salinity and favored arylesterase.•No effect of amendments on CO2 emissions•Biochars decreased CH4 but increased N2O emissions related to lower recalcitrance.
Mine tailings are a characteristic of landscapes where mineral extraction has occurred. These tailings usually contain high heavy metal concentrations and have low fertility. In arid and semiarid ...zones, erosion may be an additional problem. The removal of these tailings is often impractical due to their large volumes. Therefore, a need exists to develop in situ low cost technologies to effect surface stabilization. The use of vegetation can be an attractive option, since there are some native plant species that can colonize parts of these polluted sites unaided. Some edaphic factors were investigated, including heavy metal concentrations, in three mine tailings from a semiarid mining zone in Southeast Spain. High total metal concentrations were found: 5000–8000 mg/kg for lead and 7600–12
300 mg/kg for zinc. Two of these mine tailings had pH values between 6 and 7, while the other was acidic, with a pH of 2.5. Metal solubility was pH dependent, with more than 10% of the total zinc soluble in the acid substrate and less than 1% in the neutral substrates. The metal concentrations (copper, lead and zinc) in shoots of native vegetation colonizing in these sites were studied. No species of hyperaccumulators were found. The highest concentrations were found in
Zygophyllum fabago, with 530 mg/kg zinc,
Helichrysum decumbens with 390 mg/kg lead, and
Tamarix sp. with 11 mg/kg copper. An analysis of the rhizospheric soil of these plants indicated that
Lygeum spartum grew in pH 3 soil and had low metal concentration in shoots (40 mg/kg zinc and 41 mg/kg lead).
•Correlate Electrical Resistivity Tomography with metallic concentration data.•Modelling spatial distribution of heavy metal concentrations statistically.•Assessment of a forsaken phosphogypsum pond ...efficiently.
One of the wastes generated in fertiliser production from phosphoric rock is phosphogypsum, whose mismanagement lead to environmental and health risks. Therefore, a detailed evaluation of the chemical composition of phosphogypsum is necessary to determine effective means of its management. Due to the high amount of generated waste, the cost and time consumed for this characterisation by chemical analysis is limiting. Hence, efficient tools should be developed to predict the chemical composition of this waste. Thus, this study aims to: 1) determine the physic-chemical characterisation of phosphogypsum pond using geochemical and geophysical techniques and 2) predict the heavy metals spatial distribution through statistical models. Results show that the most concentrate metal is chromium with a maximum of ≈900 mg.kg−1 and cadmium is the least concentrated (maximum ≈23 mg.kg-1). The Electrical Resistivity Tomography revealed the superposition of two layers. The top one (waste) presents low resistivity (≈17Ω.m) while the bottom layer shows higher resistivity (>124Ω.m). Metal concentrations and resistivities were combined by applying non-linear regression models. Cr showed the strongest correlation (R2 = 0.68), yielding an accurate model that was used for revealing the spatial distribution of the highest Cr concentrations in the pond, with the consequent reduction of expensive traditional methods.
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