Water use dynamics of almond and pistachio crops in the Mediterranean region amid climate change
Almond and pistachio are socio-economically significant tree crops grown in California’s San Joaquin Valley (SJV). Continuing commercial production with efficient irrigation planning under changing climate requires an extensive understanding of their biophysical interactions such as altered phenology, biomass accumulation, transpiration, and other processes. This study examines the phenology and water use (ETc) responses of almonds and pistachios under two scenarios: climate change (warming-only) and climate change with elevated atmospheric CO2 (eCO2), using an agrohydrological model, VIC-CropSyst. The model was calibrated and validated using observations on crop evapotranspiration. The simulated crop responses to warming-only and eCO2 revealed compounding effects on chill accumulation, phenology, biomass accumulation, and eventually on crop water use. The active growth period from bud break to dormancy was prolonged by 10–25 days for both crops under simulated Representative Concentration Pathways (RCP4.5 and RCP8.5) scenarios compared to the baseline. The annual ETc under warming-only scenarios showed a slight increase for almonds (1 % under RCP4.5 and 3 % under RCP8.5) and a higher increase for pistachios (8 % under both RCP4.5 and RCP8.5) by the mid-21st century. These increases in ETc translate to 260 (almonds) and 180 (pistachios) million m3/year of additional water for irrigation in the absence of eCO2 effects. The eCO2 is expected to moderately reduce irrigation demand by 35 million m3/year for almonds and increase by 140 million m3/year for pistachios over the baseline. The outcomes can guide decision-makers to anticipate potential threats and concoct adaptive strategies by managing irrigation and choosing suitable cultivars or alternate crops.
https://doi.org/10.1016/j.agwat.2024.109219
Native cover crops enhance biodiversity and ecosystem services in hazelnut orchards
Agroecological restoration aims to restore biodiversity and ecosystem function in agricultural landscapes while sustaining crop production. Adopting native plants as cover crops may restore ecological value to cropping systems such as nut orchards. We focused on Oregon hazelnut orchards and compared how four seed mixes (native annuals, native perennials, conventional cover crops and unseeded controls) performed under three levels of orchard floor disturbance (flailing, flailing and scraping, and unmanaged/none) across three different orchard ages with corresponding differences in canopy shade over a 2-year period. We evaluated cover crop performance by three criteria: the survival criteria (response to disturbance and shading), the production criteria (effects on weeds, erosion potential and soil moisture) and the ecological functioning criteria (abundance and diversity of native plants and pollinator visitations). We found that native species generally outperformed conventional cover crops and bare ground across these criteria. Plant survival was not affected by disturbance but shading reduced survival of most species. Native annuals had high cover in the first year, and native perennials had high cover across both years. Native perennial species provided the best weed reduction and erosion control while not reducing soil moisture, and hosted the highest pollinator abundances and diversity. Synthesis and applications. Our results suggest that agroecological restoration of orchards through native cover cropping is a viable strategy for improving ecological outcomes without compromising production needs.
https://doi.org/10.1111/1365-2664.14850
Intercropping alfalfa during almond orchard establishment reduces winter soil nitrogen and water losses, provides on‐farm revenue
The ecosystem benefits linked to intercropping and diversified agroecosystems is an area with increasing research interest, particularly in sustainable food production and farm resilience to extreme climate variability. Interrow cropping of alfalfa (Medicago sativa L.) in almond [Prunus dulcis (Mill.) D. A. Webb] orchards during the 3–4 non-bearing, establishment years has potential to advance sustainable intensification in agricultural regions such as the Central Valley of California. In this study we evaluated ecosystem benefits linked to this intercropped agroecosystem in contrast to conventional almond systems with interrow spaces maintained bare. From Winter 2023 to Spring 2024 (157 days), we modeled soil hydrological properties (HYDRUS-1D) and quantified soil nitrogen using various approaches. Simulation from HYDRUS revealed that winter soil evaporative loss was most substantial for a flood-irrigated bare-soil control (208.1 mm) and lowest for the alfalfa intercropped interrow (59.2 mm). Estimated soil water storage was lowest in the alfalfa intercropped interrow and highest for bare-soil controls, indicating continuous plant water uptake throughout the winter period when almond trees are dormant. Winter soil N loss measured using suction lysimeters, ion exchange soil resins traps, and soil sampling (0–120 cm) indicated that N leaching was greatest in the bare-soil interrow spaces and lowest for alfalfa intercropped treatment. The utilization of free winter inputs, such as rainwater and slow-release mineralized N from dairy manure compost, translated to a 2.22 tonne ha−1 alfalfa yield and equated to a $500 ha−1 gross revenue for the first alfalfa cutting. Overall, the preliminary ecosystem benefits observed in this unique alfalfa–almond intercropped agroecosystem were attributed to augmentation in farm resource use efficiency and revenues generated during the winter season.
https://doi.org/10.1002/agg2.70024
Pecan-medicinal crops intercropping improved soil fertility and promoted interactions between soil microorganisms and metabolites
Background: Pecan [Carya illinoinensis (Wangenh.) Koch] is a widely cultivated dried fruit and woody oil tree with high economic value. Continuous sole planting of pecan caused some land to lie idle and deterioration of soil conditions. Tree and medicinal crops intercropping represents an environmental-friendly and economically feasible solution to these issues. Thus, we aimed to explore the underlying mechanism by which intercropping improved soil condition by regulating the interactions of the soil microbiome and metabolome. In this study, pecans were intercropped with medicinal crops caper spurge and honeysuckle on a tree farm in China. A combined analysis of soil microbiomes and metabolomes was performed to discover the effects of intercropping on bulk and rhizosphere soils. Results: The results showed that intercropping improved the edaphic properties of bulk soil and promoted the growth of pecan and caper spurge. Intercropping also significantly altered the structures of both bacterial and fungal communities in bulk soil, stabilised the enrichment of nitrogen-cyclic bacteria, for instance, Bacillus, and decreased the relative abundances of plant–pathogenic fungi, for instance, Fusarium. In addition, the result of metabolomic analysis showed that intercropping promoted the synthesis of functional compounds, such as trehalose and ethanolamine, which enhanced plant disease resistance in bulk soils. Moreover, the co-occurrence networks of microbiomes and metabolomes of bulk soils revealed that Bacillus was significantly correlated with Fusarium, Alternaria, and trehalose under intercropping patterns. Furthermore, analysis of microbiomes and metabolomes in the rhizosphere soil of caper spurge and honeysuckle revealed that Penicillium and Rhizomicrobium were significantly increased by intercropping and showed more dynamic connections with other genera and metabolites compared with single planting. Conclusions: Overall, intercropping pecans with caper spurge and honeysuckle can improve soil conditions and promote plant growth through microbiological and metabolomics integrated analyses. This study provides valuable information and theoretical basis for optimizing land resource utilisation and improving soil conditions in tree fields like pecan fields via intercropping, thereby reducing production losses and ensuring economic benefits.
https://doi.org/10.1186/s40538-024-00693-8
Drought and heat stress interactions: Unveiling the molecular and physiological responses of Persian walnut
While numerous studies explored the response of walnut plants to drought stress (DS), there remains a significant gap in the knowledge regarding the impact of heat stress (HS) and the combined effects of DS and HS on the recovery capacity of walnut trees. This study aimed to investigate the mechanism of Persian walnut (cv. Chandler) response to the combined DS and HS, focusing on various aspects including photosynthesis, water relations, and osmotic regulation. The treatments involved subjecting plants to DS (through a withholding method for 24 d), HS (gradually up to 40 °C for 8 d), and a combined DS and HS, which were compared to a control group (no stress) during the stress and recovery phases. The results showed that DS had significantly more negative effects on chlorophyll content, relative water content (RWC), leaf water potential (WP), osmotic potential (OP) compared to HS. Involvement of osmoregulation mechanism was detected more in DS and HS plants through the accumulation of proline, glycine Betaine and total soluble carbohydrates. The functionality of photosynthesis was significantly impacted by both HS and DS, respectively. While the HS accelerated the change of the abovementioned physiological processes in drought-stressed seedlings. Consistently, more pronounced damage was found in leaves under the combined stress, alongside the decrease RWC, chlorophyll content and fluorescence ratios. Based on the analysis of the linear mixed-effect model, the effects of combined stress and HS on photosynthesis parameters were detected in the early stages of stress compared to DS. Within a range of stresses, the abovementioned physiological processes of individual and combined-stressed plants recovered to levels comparable to those of the control. Our results also showed a substantial reduction in the expression of the photosynthetic genes (Fd, Cyt b6f, and PsbB) in Persian walnut saplings under abiotic stress conditions indicating significant damage to their photosynthetic apparatus. This study highlights that, under scenarios of aggravating drought occurring with heat, walnut seedlings could face a high risk of damage to physiological structures in relation to the synergistically increased hydraulic and thermal impairments.
https://doi.org/10.1016/j.plaphy.2024.109237
Sustainable livelihoods through cashew cultivation: insights from smallholder farmers in the southern region of India
Cashew cultivation has emerged as an important agricultural activity in promoting sustainable livelihoods for smallholder farmers. The present study investigates the impacts of cashew cultivation on sustainable livelihoods of smallholder farmers in the Southern region of India, addressing a significant research gap in the understanding of how this crop affects various aspects of farmers' lives. Using a mixed-methods approach, the study reveals that, cashew farming significantly increases farmers’ income, leading to improvements in food security, education, social status, and standard of living. These findings contribute to new insights into the socio-economic and environmental dimensions of cashew cultivation, offering a holistic understanding of its role in rural development. Additionally, the study also emphasizes the need for government policies supporting smallholders in cashew farming, including training, access to quality seeds, and best agricultural practices. Social welfare initiatives and cooperatives can improve the overall well-being of cashew farming communities. Research and development should prioritize climate-resistant cashew varieties to address environmental challenges linked to cashew cultivation. The study’s results also provide a foundation for future research and policy formulation aimed at enhancing the practice of cashew farming for sustainable livelihoods.
https://doi.org/10.1007/s43621-024-00558-y
Incorporating date palm fibers for sustainable friction composites in vehicle brakes
The demand for eco-friendly materials in automotive components has spurred research into natural fibers as sustainable alternatives for brake pads. This study examines the potential of date palm fibers, particularly the palm frond midrib (PFM), in brake pad composites. The effects of epoxy, PFM, and calcium carbonate on the composites’ mechanical and tribological properties were analyzed. The optimal formulation (25% epoxy, 30% PFM, 35% calcium carbonate) exhibited superior properties, including a hardness of 87 HRB, wear rate of 1.5E-03 mg/mm, and COF of 0.73, surpassing commercial pads. Additionally, an inverse relationship between PFM/calcium carbonate content and compressibility was observed, with increased calcium carbonate enhancing wear resistance. This research underscores the potential of utilizing date palm resources in eco-friendly brake manufacturing, reducing the environmental and health impacts of traditional materials. https://doi.org/10.1038/s41598-024-73275-1
Phenolic compounds from macadamia husk: An updated focused review of extraction methodologies and antioxidant activities
This review explores the potential of agri-food waste materials, with a particular focus on macadamia nut by-products. Industrial processing of macadamia nuts yields a significant volume of by-products, including green husk and woody shell. Recent research has highlighted these by-products as readily available, cost-effective rich sources of phenolic compounds, renowned for their potent antioxidant and antibacterial properties. This paper emphasizes the importance of selecting an optimal extraction method to fully harness the bioactive potential of these phenolic compounds. In this work, we provide a comprehensive overview of conventional and advanced extraction techniques that are used to extract phenolic compounds from macadamia by-products, with a particular focus on the methods applied to macadamia green husk. Among the various techniques, it appears that ultrasound-assisted extraction, especially when combined with aqueous organic solvents, is more efficient than other methods for this purpose. This review also addresses the challenges in phenolic compound recovery, primarily due to the lack of a standardized extraction process. This often results in the extensive use of extraction solvents to achieve an extract that is rich in phenolic compounds. Overall, this research offers a valuable understanding of the most effective methods for the extraction and recovery of phenolic compounds from macadamia by-products and discusses the potential for scaling up these extraction processes. Hence, it can serve as a useful resource for researchers and industry professionals interested in sustainable and efficient utilization of by-products of the nut industry. https://doi.org/10.1016/j.fbp.2024.09.014
Cashew Nut Shell Waste Derived Graphene Oxide
The particular properties of graphene oxide (GO) make it a material with great technological potential, so it is of great interest to find renewable and eco-friendly sources to satisfy its future demand sustainably. Recently, agricultural waste has been identified as a potential raw material source for producing carbonaceous materials. This study explores the potential of cashew nut shell (CNS), a typically discarded by-product, as a renewable source for graphene oxide synthesis. Initially, deoiled cashew nut shells (DCNS) were submitted to pyrolysis to produce a carbonaceous material (Py-DCNS), with process optimization conducted through response surface methodology. Optimal conditions were identified as a pyrolysis temperature of 950 °C and a time of 1.8 h, yielding 29.09% Py-DCNS with an estimated purity of 82.55%, which increased to 91.9% post-washing. Using a modified Hummers method, the Py-DCNS was subsequently transformed into graphene oxide (GO-DCNS). Structural and functional analyses were carried out using FTIR spectroscopy, revealing the successful generation of GO-DCNS with characteristic oxygen-containing functional groups. Raman spectroscopy confirmed the formation of defects and layer separations in GO-DCNS compared to Py-DCNS, indicative of effective oxidation. The thermogravimetric analysis demonstrated distinct thermal decomposition stages for GO-DCNS, aligning with the expected behavior for graphene oxide. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) further corroborated the morphological and compositional transformation from DCNS to GO-DCNS, showcasing reduced particle size, increased porosity, and significant oxygen functional groups. The results underscore the viability of cashew nut shells as a sustainable precursor for graphene oxide production, offering an environmentally friendly alternative to conventional methods. This innovative approach addresses the waste management issue associated with cashew nut shells and contributes to developing high-value carbon materials with broad technological applications. https://doi.org/10.3390/molecules29174168
Improved Straw Decomposition Products Promote Peanut Growth by Changing Soil Chemical Properties and Microbial Diversity
The ameliorative effects of straw decomposition products on soil acidification have been extensively studied. However, the impact of chemically treated straw decomposition products on crop productivity and the underlying microbial mechanisms remain unclear. This study aimed to investigate the effects of two dosages of Ca(OH)2-treated straw decomposition products of peanuts on red soil acidity, fertility, and bacterial and fungal diversity through a pot experiment. The pot experiment included four treatments: chemical nitrogen, phosphorus, and potassium (NPK) fertilization alone (CK), NPK chemical fertilization combined with peanut straw decomposition products (PS), NPK chemical fertilization combined with 4% Ca(OH)2-treated peanut straw decomposition products (PS4Ca), and NPK chemical fertilization combined with 8% Ca(OH)2-treated straw decomposition products (PS8Ca). High-throughput sequencing was performed to investigate the effects of these treatments on soil microbial diversity. The treatments with PS, PS4Ca, and PS8Ca significantly increased soil pH, exchangeable base cations, and nutrient content, whereas they decreased the exchangeable acid, especially exchangeable aluminum. The peanut growth improved substantially with the application of straw decomposition products. Specifically, PS4Ca significantly increased the Shannon and Richness indices of fungi. The principal coordinate analysis showed that the soil microbial communities in the straw decomposition product treatments were significantly different from CK. Linear discriminant analysis effect size identified unique bacteria and fungi between treatments. The Mantel test indicated that exchangeable base cations and pH were significantly positively correlated with bacterial communities, whereas available potassium was positively correlated with fungal communities. The partial least squares path modeling revealed that the bacterial communities positively and directly affected all peanut agronomic traits. In contrast, the fungal communities had a negative and direct effect only on peanut 100-pod weight. Therefore, adding Ca(OH)2-treated straw decomposition products could effectively improve crop productivity by alleviating soil acidification, increasing soil nutrients, and subsequently changing microorganisms.
https://doi.org/10.3390/su16167096