• Energy Research

Climate change, land degradation, and desertification lead to the loss of carbon present in the soil and plants. The carbon dioxide (CO2) concentration in the atmosphere has reached 412 ppm. This is a rise of 47% since the start of the industrial period, when the concentration was close to 280 ppm. Therefore, the sequestration of carbon from the atmosphere to earth is the need of the hour. Many scientists have suggested agroforestry as a potent instrument for climate change mitigation as well as to fetch lucrative benefits. The Indian government is also promulgating tree-based systems for increasing tree cover up to 33% of the total geographical area to mitigate climate change. Therefore, the expansion of the commercial agroforestry system of fast-growing tree species producing higher biomass could be a sustainable and ecologically benign technique to sequester carbon, increase green cover, and improve the financial status of farmers. This review highlights the commercial agroforestry systems, biomass and carbon sequestration potential, and case studies of poplar and eucalyptus. The species such as poplar (Populus deltoides), nilgiri (Eucalyptus spp.), subabul (Leucaena leucocephala), tree of heaven (Ailanthus excelsa), willow (Salix spp.), malabar neem (Melia dubia), cadamba (Neolamarckia cadamba), and white teak (Gmelina arborea) are the suitable tree species for carbon sequestration under agroforestry. Among these species, poplar and eucalyptus are major agroforestry tree species that have been adopted by millions of farmers in India since the 1990s. Indo-Gangetic plains are considered the birthplace of commercial or industrial agroforestry, as poplar and eucalyptus are widely planted. This review reports that poplar and eucalyptus have the potential to sequester carbon stock of 212.7 Mg C ha−1 and 237.2 Mg C ha−1, respectively. Further, the net carbon sequestration rate in poplar and eucalyptus was 10.3 and 12.7 Mg C ha−1 yr−1, respectively. In conclusion, the commercial agroforestry system was very successful in the Indo-Gangetic regions of the country but needs further expansion with suitable compatible crops in different parts of the country.

Climate change and extreme weather events are threatening agricultural production worldwide. The anticipated increase in atmospheric temperature may reduce the potential yield of cultivated crops. Agroforestry is regarded as a climate-resilient system that is profitable, sustainable, and adaptable, and has strong potential to sequester atmospheric carbon. Agroforestry practices enhance agroecosystems’ resilience against adverse weather conditions via moderating extreme temperature fluctuations, provisioning buffers during heavy rainfall events, mitigating drought periods, and safeguarding land resources from cyclones and tsunamis-type events. Therefore, it was essential to comprehensively analyze and discuss the role of agroforestry in providing resilience during extreme weather situations. We hypothesized that integrating trees in to the agro-ecosystems could increase the resilience of crops against extreme weather events. The available literature showed that the over-story tree shade moderates the severe temperature (2–4°C) effects on understory crops, particularly in the wheat and coffee-based agroforestry as well as in the forage and livestock-based silvipasture systems. Studies have shown that intense rainstorms can harm agricultural production (40–70%) and cause waterlogging. The farmlands with agroforestry have been reported to be more resilient to heavy rainfall because of the decrease in runoff (20–50%) and increase in soil water infiltration. Studies have also suggested that drought-induced low rainfall damages many crops, but integrating trees can improve microclimate and maintain crop yield by providing shade, windshield, and prolonged soil moisture retention. The meta-analysis revealed that tree shelterbelts could mitigate the effects of high water and wind speeds associated with cyclones and tsunamis by creating a vegetation bio-shield along the coastlines. In general, existing literature indicates that implementing and designing agroforestry practices increases resilience of agronomic crops to extreme weather conditions increasing crop yield by 5–15%. Moreover, despite its widely recognized advantages in terms of resilience to extreme weather, the systematic documentation of agroforestry advantages is currently insufficient on a global scale. Consequently, we provide a synthesis of the existing data and its analysis to draw reasonable conclusions that can aid in the development of suitable strategies to achieve the worldwide goal of adapting to and mitigating the adverse impacts of climate change.

The land suitability in the Ratnagiri district (India) for mango crop has been assessed using a combination of multi-criteria decision making (MCDM) with GIS-based analytic hierarchy process (AHP), and sensitivity analysis. Five criteria are applied in this study to analyze land suitability affecting the mango production, viz., topography, climate, soil properties, soil erosion risk, and soil and water conservation practices, all affecting mango production. To prepare the land suitability maps for the mango plants, weights of criteria were identified through expert opinions and a pairwise comparison matrix. A weighted overlay tool available in ArcGIS software was applied in this study for the weighted overlay analysis. The most sensitive parameters were identified by developing and testing a total of 26 weighting schemes. After analyzing the sensitivity of parameters, the parameters related to soil and erosion such as terracing, contour trenching, stone bund, etc. were found as the most significant factors, before and after implementing the conservation measures. As a result, it was observed in this study that after conservation practices were implemented, the area in the highly suitable (19.4%) and moderately suitable (68.8%) classes was expected to rise, while the area in the marginally suitable (7%) class was expected to decrease. This research revealed that combining MCDM with GIS-based AHP as well as sensitivity analysis techniques increased the reliability of MCDM output for each criterion.

Agroforestry integrates woody perennials with arable crops, livestock, or fodder in the same piece of land, promoting the more efficient utilization of resources as compared to monocropping via the structural and functional diversification of components. This integration of trees provides various soil-related ecological services such as fertility enhancements and improvements in soil physical, biological, and chemical properties, along with food, wood, and fodder. By providing a particular habitat, refugia for epigenic organisms, microclimate heterogeneity, buffering action, soil moisture, and humidity, agroforestry can enhance biodiversity more than monocropping. Various studies confirmed the internal restoration potential of agroforestry. Agroforestry reduces runoff, intercepts rainfall, and binds soil particles together, helping in erosion control. This trade-off between various non-cash ecological services and crop production is not a serious constraint in the integration of trees on the farmland and also provides other important co-benefits for practitioners. Tree-based systems increase livelihoods, yields, and resilience in agriculture, thereby ensuring nutrition and food security. Agroforestry can be a cost-effective and climate-smart farming practice, which will help to cope with the climate-related extremities of dryland areas cultivated by smallholders through diversifying food, improving and protecting soil, and reducing wind erosion. This review highlighted the role of agroforestry in soil improvements, microclimate amelioration, and improvements in productivity through agroforestry, particularly in semi-arid and degraded areas under careful consideration of management practices.

Poplar is popular among farmers and planted widely in the form of block and boundary systems. The preferences of farmers are shifting much more towards bund plantations due to their smaller yield reductions and can take up kharif and rabi crops till rotation. As for boundary plantations, farmers tend to grow trees in any direction without concern for yield reduction or profitability. Against this background, an experiment was designed by planting poplar at 2 m intervals in East–West (E–W) and North–South (N–S) directions during 2008 to determine the production potential and economic viability of boundary plantations and their effect on sorghum (Sorghum bicolor) and wheat (Triticum aestivum) crop rotations till harvesting of the trees. The experiment comprised three variables: stand age (years); four aspects (northern and southern E–W rows, eastern and western N–S rows; these four aspects are considered by dividing the tree lines); and six distances from tree the lines (0–3, 3–6, 6–9, 9–12, 12–15, 15–18 m and a control). A split-split plot design with three replicates was used. A significant reduction of fodder biomass of sorghum and wheat yield was observed up to 9 m distant from the tree line: the reduction was 10 to 60% for the kharif season and 7.2 to 29.5% for rabi crops from the second year to eight years after planting, respectively. Interestingly, the poplar boundary plantation had a favorable microclimatic effect from 9 to 15 m distance from the tree line, which increased crop yields compared with the control. The total dry wood production of poplar in the E–W direction (166.99 mg ha−1) was almost two times more than production for the N–S direction (82.62 mg ha−1) at 8 years of rotation. The economic analysis of this study concluded that an E–W boundary plantation of poplars exhibited the maximum net returns of INR 549,367 ha−1, a net present value of INR 222,951 ha−1, a BC ratio of 1:1.65, an IRR of 85% and an LEV of INR 1,220,337 ha−1. Therefore, it is concluded that the intercropping of a sorghum-wheat crop rotation in E–W boundary plantations was more beneficial for enhancing farm income over traditional agriculture in north India.

Although trees in the agroforestry system play diverse roles in meeting the food, fodder, wood, and energy requirements of the agrarian community, their multifunctional contribution often remains understudied, especially while assessing the socio-economic status (SES) of farmers. Therefore, we conceptualized, developed, and standardized an instrument to appraise the SES of the farmers who practice agroforestry in semi-arid and sub-humid regions of India. We also determined the consistent performance of the scale by testing the reliability using the test–retest method. We found that the validity of the scale was accepted with a high correlation, confirming the validity and reliability of the new scale. We also prepared certain norms to identify different socioeconomic levels of agroforestry farmers. The scale used 9 major, 14 moderate, and 115 relevant minor indicators to address the dynamism of the SES and the diversification of farming systems. The proposed scale was specially designed and elastic in nature so that it has a wide scope regarding local applicability and utility, such as in multi-farming systems. Hence, this scale might be considered for measuring the SES of farmers who practice agroforestry at cross-regional and national levels.