Sustainable management for increasing soil microbial diversity in a Mediterranean agro-ecosystem

Olive can be considered a paradigm species for Mediterranean agro-ecosystems. In conventional olive growing, adopted by the majority of the farmers, frequent soil tillage has reduced soil microbial diversity and microbiota complexity that strongly contribute to the overall soil fertility. Therefore, the conventional agronomic practices should evolve in a more sustainable olive management addressed to improve soil microbial diversity. A better understanding of the ecology of soil microorganisms could lead to identify agricultural management practices that stimulate and select the soil microorganisms having beneficial purposes in agriculture, such those interested in nitrogen cycle. The aim of this study was to evaluate the effects of sustainable practices (grass cover and pruning residues recycling) on soil microbioligical quality in a Mediterranean olive orchard. The trials were carried out in a mature olive grove (Olea europaea L. – cv Maiatica) located in Basilicata Region (Southern Italy.) and managed for 13 years (medium-term) according to two different soil management systems: the sustainable treatment (ST) and the conventional treatment (CT). Soil microorganisms in the two systems were monitored by both microbiological cultural-dependent and molecular methods, and by microscopy. In the ST olive orchard, soil microbiota showed a higher complexity and metabolic diversity. The adoption of ‘innovative’, sustainable, agricultural practices had positive effects on soil microbiota and its biodiversity, which in turn can influence soil fertility and plant growth by increasing nutrients availability and turnover. The results of this study encourage the use of sustainable agricultural practices able to enhance physico-chemical and microbial soil fertility and promote good-quality fruit production without detrimental effects on water and soil resources. The role of the identified microorganisms in the soil microbial netwo rk is discussed, in order to provide a detailed view of the impact that man-made selection had on soil microorganisms of agricultural relevance in a typical Mediterranean agronomic biosystem

Postharvest regulated deficit irrigation in peach tree in a Mediterranean environment: effect on vegetative growth and yield

The aim of this paper was to verify the possibility to reduce irrigation water requirements by applying regulated deficit irrigation (RDI) during phenological stages less sensitive to water deficit. The effects of two different levels of RDI were studied in a peach orchard (cv Springcrest). From bud break to harvest, irrigation was managed by applying 100% ETc, while from harvest to early autumn, irrigation was equivalent to 100%, 50% and 25% ETc. During the trial, no significant reductions in yield or quality were found for the 50% ETc treatment, whereas about 1,000, 1,800 and 2,400 m3 ha-1 of water were saved in the first, the second and the third year. The 25% treatment did reduce quality and yield significantly. Under scarce water supply conditions, a clear benefit can be obtained through the use of 50% RDI during the post-harvest period, especially for early harvest peache

Variability of total soil respiration in a Mediterranean vineyard

Total soil respiration (TSR) is the major component of the CO2 global flux. The knowledge of the temporal-spatial variability of TSR allows for a better interpretation of a critical component of global greenhouse gas flux measurements. The objective of the research was to evaluate the TSR dynamic over a long measurement period in a vineyard in the South of Italy. A static home-made automatic system was used to measure TSR for a three year period. A portable gas analyser (Li-Cor 6400-09) was used to study TSR spatial variability. A non-invasive geophysical technique (Electromagnetic Induction – EMI) was applied to search for a significant relationship between apparent soil electrical conductivity (ECa), the EMI signal and TSR. Long-term measurements of TSR enabled to study its temporal dynamics. CO2 rates ranged from 0.78 to 43.7 g CO2 m–2 day–1. TSR increased during spring and decreased by 45–50% during the mid-summer. The daily trend of TSR showed differences between the seasons studied reporting a clearly variation among TSR measured on row and inter-row positions. The supplemental irrigation significantly affected (P < 0.001) CO2 soil effluxes which showed a weekly mean increase of 300%. Significant inverse relationships were found by interpolating TSR values and ECa (coefficient of correlation ranging from –0.43 to –0.83 at P < 0.001). The spatialisation of TSR at field scale was performed using the linear regression between TSR values and EMI signals. TSR spatialisation gave a more detailed view of CO2 emissions distribution within the vineyard. EMI technique could be a useful tool to compute accurately the global CO2 emissions which are a complex and hard to measure component of the agrosystem carbon balance

Contro Xylella su olivo le buone pratiche agronomiche

Per combattere il batterio è necessario guardare all’oliveto nel suo insieme e migliorarne il «sistema immunitario» adottando pratiche agronomiche sostenibili che aumentino le capacità delle piante a contrastare gli stress biotici e abiotici. Così facendo è possibile convivere con il batterio limitandone la diffusione e recuperando le piante infette

Mediterranean Cropping Systems: The Importance of Their Economic and Environmental Sustainability

The COVID-19 pandemic has drastically changed the lives of people, as well as the production and economic systems throughout the world. The flow of raw materials and products, the supply of labor and manpower, and the purchasing power have all been changed to the detriment of individual health and well-being. Such a situation requires placing even more emphasis on the search for virtuous agricultural systems compatible with the goals of economic and environmental development so clearly defined at the world level in the last decades. The present study aimed to assess the environmental and economic performance of some typical Mediterranean crops grown under different agronomical management regimes, such as strawberry, hazelnut, apricot tree, kiwifruit, peach, olive tree, and grapevine, to emphasize the importance of the mentioned issues even in the current pandemic situation. Life cycle assessment (LCA) was used to investigate the environmental profile of the studied crops, while lifecycle costing (LCC) was performed to assess and compare the economic aspects. From the environmental perspective, the hobby-organic olive systems were the most eco-friendly cropping systems, emitting 0.031 to 0.105 kg CO2eq per kg olives, while the organic hazelnut system had the greatest impact (1.001 kg of CO2eq per kg). Apricot, kiwifruit, and peach systems used N and P inputs most effectively, while strawberry systems efficiently used fossil fuels. Olive HO-2, kiwifruit, and peach cropping systems had the lowest budgets, with the costs amounted to 0.12 € kg-1 per fruit for Olive HO-2 and 0.28 € kg-1 per fruit for both kiwifruit and peach. On the contrary, organic strawberry cultivation was the most expensive (4.77 € kg-1). The variability in results due to the large differences between contexts, such as landscape, technical knowledge, and crop management, characterized the studied agricultural systems. To easily identify sustainability classes and to diminish the impact of farming practices, a considerable effort should be expended to combine LCA with LCC, C sequestration estimates, and some other useful indicators for the environmental quality evaluation

Chemical, biochemical and microbiological properties of soils from abandoned and extensively cultivated olive orchards

The abandonment of olive orchards is a phenomenon of great importance triggered mainly by economic and social causes. The aim of this study was to investigate some chemical, biochemical and microbiological properties in a soil of a Southern olive grove abandoned since 25 years. In order to define the effect of the long-term land abandonment on soil properties, an adjacent olive grove managed according to extensive practices was taken as reference (essentially minimum tillage and no fertilization). Soil organic matter, total nitrogen and pH were significantly higher in the abandoned olive grove due to the absence of tillage and the natural inputs of organic matter at high C/N ratio which, inter alia, increased the number of cellulolytic bacteria and stimulated the activity of β-glucosidase, an indicator of a more advanced stage of soil evolution. The soil of the abandoned olive orchard showed a lower number of total bacteria and fungi and a lower microbial diversity, measured by means of the Biolog® method, as a result of a sort of specialization trend towards low quality organic substrates. From this point of view, the extensive cultivation management seemed to not induce a disturbance to microbiological communities

Phyllosphere and carposphere bacterial communities in olive plants subjected to different cultural practices

The aim of this study was to characterize phyllosphere and carposphere bacterial communities of olive trees subjected for 13 years to two different soil management systems (sustainable and conventional) in a mature olive grove located in Southern Italy. Amplified DNA fragments of the 16S ribosomal RNA eubacterial gene (16S rRNA) of bacteria living on leaf and fruit surface, and in fruit pulp were analyzed by denaturing gradient gel electrophoresis (DGGE). A clone library of 16S rRNA amplicons extracted from the bacteria living in pulp homogenates and a phylogenetic analysis were performed. Generally, the DGGE patterns of the bacteria from both the treatments clustered separately. The medium-term sustainable orchard management resulted in a higher number of bacterial species from olive fruit pulp. Phyllosphere and carposphere communities evaluated by DGGE were affected by the type of the agricultural practices adopted. A better understanding of phyllosphere and carposphere microbiota of cultivated olive plants could be useful for the promotion of plant growth, a better plant protection and a higher crop quality

The Fall in Antibody Response to SARS-CoV-2: a Longitudinal Study of Asymptomatic to Critically Ill Patients Up to 10 Months after Recovery

The aim of this study was to assess the long-term dynamics and factors associated with the serological response against the severe acute respiratory syndrome coronavirus 2 after primary infection. A prospective longitudinal study was conducted with monthly serological follow-up during the first 4 months, and then at 6, 8, and 10 months after the disease onset of all recovered adult in- and outpatients with coronavirus disease 2019 (COVID-19) attending Udine Hospital (Italy) during the first wave (from March to May 2020). A total of 546 individuals were included (289 female, mean age 53.1 years), mostly with mild COVID-19 (370, 68.3%). Patients were followed for a median of 302 days (interquartile range, 186 to 311). The overall seroconversion rate within 2 months was 32% for IgM and 90% for IgG. Seroreversion was observed in 90% of patients for IgM at 4 months and in 47% for IgG at 10 months. Older age, number of symptoms at acute onset, and severity of acute COVID-19 were all independent predictors of long-term immunity both for IgM (beta, linear regression coefficient, 1.10, P = 0.001; beta 5.15 P = 0.014; beta 43.84 P = 0.021, respectively) and for IgG (beta 1.43 P < 0.001; beta 10.46 P < 0.001; beta 46.79 P, 0.001, respectively), whereas the initial IgG peak was associated only with IgG duration (beta 1.12, P < 0.001). IgM antibodies disappeared at 4 months, and IgG antibodies declined in about half of patients 10 months after acute COVID-19. These effects varied depending on the intensity of the initial antibody response, age, and burden of acute COVID-19

Effects of Organic Additives on Chemical, Microbiological and Plant Pathogen Suppressive Properties of Aerated Municipal Waste Compost Teas

The aim of the present study was to characterize the physical-chemical and microbiological features of aerated compost teas (CTs) extracted with dechlorinated tap water and with two different additives, molasses and whey, in increasing doses. Plant pathogen suppression properties of CTs were also taken into account. Total nitrogen in CTs increased with rising doses of the additives used. In spite of this, nitrogen and mineral element contributions were limited but complementary for plant mineral nutrition. Although total heavy metal contents in CTs were low, an increase of their bioavailable forms (ionic and chelated forms, presence in microorganisms) should be taken into account. In addition, the distribution on soil of acid and/or chelating products by CTs could increase the bioavailability of heavy metals, especially in the case of several annual distribution cycles and of medium–long term treatments. Additives modulated the structure and composition of microbial communities and CTs, exhibiting a broad spectrum of suppressive properties against plant pathogens, especially when they were used in a raw form