Estimating carbon sequestration potential of existing agroforestry systems in India

India launched National Agroforestry Policy on 10th February, 2014 which has the potential to substantially reduce poverty in rural India and revive wood based industry, besides integrating food production with environmental services. The policy is not only crucial to India’s ambitious goal of achieving 33 per cent forest and tree cover but also to mitigate GHG emissions from agriculture sector. Dynamic CO2FIX-v3.1 model has been used to estimate the carbon sequestration potential (CSP) of existing agroforestry systems (AFS) for simulation period of 30 years in twenty six districts from ten selected states of India. The observed number of trees on farmers’ field in these districts varied from 1.81 to 204 per hectare with an average value of 19.44 trees per hectare. The biomass in the tree component varied from 0.58 to 48.50 Mg DM ha^?1, whereas, the total biomass (tree and crop) ranged from 4.96 to 58.96 Mg DM ha^?1. The soil organic carbon ranged from 4.28 to 24.13 Mg C ha^?1. The average estimated carbon sequestration potential of the AFS, representing varying edapho-climatic conditions, on farmers field at country level was 0.21 Mg C ha^?1yr^?1. At national level, existing AFS are estimated to mitigate 109.34 million tons CO₂ annually, which may offsets one-third (33 %) of the total GHG emissions from agriculture sector.     

Contribution of trees to soil carbon sequestration under agroforestry systems in the West African Sahel

Consequent to recent recognition of agricultural soils as carbon (C) sinks, agroforestry practices in the West African Sahel (WAS) region have received attention for their C sequestration potential. This study was undertaken in the Ségou region of Mali that represents the WAS, to examine the extent of C sequestration, especially in soils, in agroforestry systems. Five land-use systems were selected in farmers’ fields [two traditional parkland systems, two improved agroforestry systems (live fence and fodder bank), and a so-called abandoned land]. Soil samples taken from three depths (0–10 cm, 10–40 cm, and 40–100 cm) were fractionated into three size classes (2,000–250 μm, 250–53 μm, and <53 μm) and their C contents determined. Whole-soil C contents, g kg⁻¹ soil, across three depths ranged from 1.33–4.69 in the parklands, 1.11–4.42 in live fence, 1.87–2.30 in fodder bank, and 3.69–5.30 in abandoned land; and they correlated positively with silt + clay content. Using the ¹³C isotopic ratio as an indicator of relative contribution of trees (C3 plants) and crops (C4 plants) to soil C, more tree-origin C was found in larger particle size and surface soil and indicated that long-term tree presence promoted storage of protected C in deeper soil. Existing long-standing agroforestry practices of the region such as the parklands seemed to have little advantage for sequestering additional C, whereas improved agroforestry practices such as live fence and fodder bank introduced in treeless croplands seemed to be advantageous.     

Carbon sequestration: An underexploited environmental benefit of agroforestry systems

Agroforestry Systems - Agroforestry has importance as a carbon sequestration strategy because of carbon storage potential in its multiple plant species and soil as well as its applicability in...     

Modeling analysis of potential carbon sequestration under existing agroforestry systems in three districts of Indo-gangetic plains in India

The Indo-gangetic plains (IGP) in India occupies 13 % of the total geographical area and produces 50 % of total food grain to feed 40 % population of the country. Dynamic CO2FIX model v3.1 has been used to assess the baseline (2011) carbon and to estimate the carbon sequestration potential (CSP) of agroforestry systems (AFS) for a simulation period of 30 years in three districts viz. Ludhiana (upper IGP in Punjab), Sultanpur (middle IGP in Uttar Pradesh) and Uttar Dinajpur (lower IGP in West Bengal) respectively. The estimated numbers of trees existing in farmer’s field on per hectare basis in these districts were 37.95, 6.14 and 6.20, respectively. The baseline standing biomass in the tree components varied from 2.45 to 2.88 Mg DM ha^?1 and the total biomass (tree + crop) from 11.14 to 25.97 Mg DM ha^?1 in the three districts. The soil organic carbon in the baseline ranged from 8.13 to 9.12 Mg C ha^?1 and is expected to increase from 8.63 to 24.51 Mg C ha^?1. The CSP of existing AFS (for 30 years simulation) has been estimated to the tune of 0.111, 0.126 and 0.551 Mg C ha^?1 year^?1 for Sultanpur, Dinajpur and Ludhiana districts, respectively. CSP of AFS increases with increasing tree density per hectare. Site specific climatic parameters like monthly temperature, annual precipitation and evapotranspiration also moderates the CSP of AFS. The preliminary estimates of the area under AFS’s were 2.06 % (3,256 ha), 2.08 % (6,440 ha) and 12.69 % (38,860 ha) in Sultanpur, Dinajpur and Ludhiana respectively.     

Soil carbon stock in olive groves agroforestry systems under different management and soil characteristics

The atmospheric concentrations of greenhouse gases have increased to unprecedented levels during last decades, raising concerns about their effect on climate change. Agriculture and land use change play an important role in atmospheric CO₂ emission and fixation, especially by affecting the soil carbon (C) storage. In this context, agroforestry systems (AFSs) could play an important role contributing to climate change mitigation. Given the importance of olive cultivation in the Mediterranean region, it is important to investigate soil C stock in olive groves, and to assess which agronomic practices could improve the soil C stock in these systems. For this reason, a study was conducted in different olive groves, including conventional and organic management, and a typical silvopastoral AFS. Furthermore, an abandoned olive grove and nearby forest were examined as a comparison. Soil samples were collected in each farm and analysed for C content and physico-chemical characteristics. This study indicates that, irrespective of the management, olive groves in the Umbria region of Italy are characterised by a high level of soil C stock if compared to those growing in other areas and to forest ecosystems, indicating that the practices adopted in the area are not negatively affecting soil C storage. A slightly lower soil C stock was measured in the silvopastoral AFS in comparison to the other farms, while high soil C stock was associated with the use of pomace, suggesting that this practice can be used to further increase soil C stock in olive orchards.

     

Soil organic carbon under a linear simultaneous agroforestry system in Uganda

The objective of this study was to quantify and compare the amount and distribution of soil organic carbon (SOC) under a linear simultaneous agroforestry system with different tree species treatments. Field work was conducted at Kifu National Forestry Resources Research Institute in Mukono District, Central Uganda, in a linear agroforestry system established in 1995 with four different tree species and a crop only control treatment. Soil samples were collected in 2006 at three depths; 0–25, 25–50, and 50–100 cm, before planting and after harvesting a maize crop. The results indicate that an agroforestry system has significant potential to increase SOC as compared to the crop only control. There was no significant difference in the amount of SOC under exotic and indigenous tree species. Among the exotic species, Grevillea robusta had higher SOC than Casuarina equisetifolia across the entire depth sampled. There is significant difference in SOC among the indigenous species, where Maesopsis eminii has more SOC than Markhamia lutea. Distance from the tree row did not significantly influence SOC concentration under any of the tree species. In selecting a tree species to integrate with crops that will sequester reasonable quantities of carbon as well as boost the performance of the crops, a farmer can either plant an exotic species or an indigenous. In this study, the soil under Grevillea robusta and Maesopsis eminii have the highest potential to store organic carbon compared to soil under other tree species.     

Carbon sequestration of modern Quercus suber L. silvoarable agroforestry systems in Portugal: a YieldSAFE-based estimation

Modern alley cropping designs, with trees aligned in rows and adapted to operating farming machinery, have been suggested for Europe. This paper explores the potential for adoption of cork oak (Quercus suber L.) agroforestry in Portugal and estimates the potential carbon sequestration. Spatial modeling and Portuguese datasets were used to estimate target areas where cork oak could grow on farmland. Different implementation scenarios were then modeled for this area assuming a modern silvoarable agroforestry system (113 trees ha^?1 thinned at year 20 for establishing 50 trees ha^?1). The YieldSAFE process-based model was used to predict the biomass and carbon yield of cork oak under low and high soil water holding capacity levels. Approximately 353,000 ha are available in Portugal for new cork oak alley cropping. Assuming implementation rates between 10 % of the area with low soil water capacity (60 mm: 15 cm depth, coarse texture) and 70 % of the area with high soil water holding capacity (1,228 mm: 200 cm depth, very fine texture), then carbon sequestration could be 5 × 10⁶ and 123 × 10⁶ Mg CO₂ respectively. Due to higher yields on more productive land, scenarios of limited implementation in high productivity locations can sequester similar amounts of carbon as wide implementation on low productivity land, suggesting that a priori land classification assessments can improve the targeting of land and financial incentives for carbon sequestration.     

Farming carbon: an economic analysis of agroforestry for carbon sequestration and dryland salinity reduction in Western Australia

The widespread removal of native trees from the agricultural zone and replacement with annual crops and pastures is a major cause of dryland salinity in Australia. It has been recognised that a large proportion of the landscape needs to be replanted to trees to prevent further salinisation. However, for much of the agricultural zone, agroforestry is not an option due to lack of species that can viably generate the products currently demanded by the market. The emerging carbon market may provide a new agroforestry option for landholders, through carbon sequestration. This analysis assesses the viability of growing trees for the purpose of selling carbon credits, from a landholder’s perspective. Benefits of trees in preventing the onset of dryland salinity are accounted for. Two regions in Western Australia; a low rainfall (330 mm/year) region and a medium rainfall (550 mm/year) region, are analysed. At the expected carbon price of A$15/tCO₂-e, growing trees for carbon is not a viable alternative for landholders in the low rainfall region, due to low sequestration rates. In the medium rainfall region, growing trees for carbon and timber is a viable alternative; however the opportunity costs of land mean the carbon price would still need to be higher than expected for growers to choose this alternative. Accounting for the salinity prevention benefits makes growing trees a more attractive investment for landholders in both regions. However in both regions, even after accounting for salinity benefits, the price of carbon would need to be A$25–A$46/tCO₂-e higher than expected to make growing trees a worthwhile investment.     

Soil enzyme activities under agroforestry systems in northern Jiangsu Province

The authors presented the enzyme characteristics of catalase, sucrase, urease and alkaline phosphatase under agroforestry systems in northern Jiangsu Province. The results show that soil enzyme activities reduce gradually from top to bottom layer of the soil profile, and the fluctuations of catalase and urease are smaller than those of sucrase and alkaline phosphatase. Soil enzyme activities differe significantly in different samples, and the order is arranged as poplar-crop intercropping segment (A, D) > paulownia-crop intercropping segment (B, C) > CK. Furthermore, soil enzyme activities increase with intercropping age. On the other hand, in the same plot, there are closer relationships between enzymes in the soil samples. Catalase, alkaline phosphatase and urease are negatively related, while alkaline phosphatase and urease are positively related (except in samples B and C). In addition, the enzyme activities have a close relationship with the fertilizers. Catalase is positively correlated with the soil pH value (r = 0.854, 0.804, 0.078 and 0.082, respectively), and is negatively correlated with total N (r = –0.201, –0.529, –0.221 and –0.821, respectively), total P (r = –0.143, –0.213, –0.362 and –0.751, respectively) and available P (r = –0.339, –0.351, –0.576, and –0.676, respectively). Sucrase, urease and alkaline phosphatase are negatively correlated with the pH value, while positively correlated with the other fertilizers (r 1). The authors suggest that enzyme activity will be a great potential as an indicator of soil quality.     

Fertilizers in agroforestry systems

This review encompasses results of fertilization experiments on several agroforestry systems—alley cropping, perennial shade systems, home gardens—in which fertilizer use is a likely management alternative. Fertilizer response was found to be most common in alley cropping, variable in perennial shade systems, and rarely reported in home gardens. Level of nutrient removal in harvested products is probably the overriding factor in determining fertilizer response; greater accumulation of organic residues, slower growth under shade, and longer periods of nutrient uptake probably also contribute to the relatively smaller fertilizer response of the perennial shade systems and home gardens. Considerable knowledge gaps exist regarding the breakdown of organic residues, and interactions between mineral and organic amendments. Systems based on annual crops (e.g., alley cropping) are likely to be less nutrient-efficient and sustainable than systems based on perennial crops, due to reduced fixation and transfer of N to the crops, the tendency of the trees to compete for and sequester nutrients, relatively high P requirements of the crops, and the high labor cost of tree management. The possible benefits of fertilization of specific components in home gardens, and relative advantages of including low-value tree legumes, high-value shade trees, and fertilization in shaded perennial systems are only beginning to receive research attention.     

Soil and litter fauna of cacao agroforestry systems in Bahia,Brazil

Agroforestry systems deposit great amounts of plant residues on soil and this leads to high levels of soil organic matter content and has increased soil biodiversity and improved its conservation. This study compares the distribution of meso and macrofaunal communities in soil and litter under cacao agroforestry systems and in a natural forest in the southern Bahia state of Brazil. Soil and litter samples were obtained in September 2003, February 2004, and August 2004 in five cacao agroforestry systems. The systems evaluated included: cacao renewed under Erythrina sp. (Erythrina poeppigiana) (CRE); cacao renewed under natural forest (Cabruca, CRF); an old cacao system under Erythrina sp. (OCE); an old cacao system under a natural forest system (Cabruca, OCF) and a cacao germplasm collection area (CGC). As a reference soil and litter under a natural forest (NF) was included. Organisms were collected over a 15-day period with a Berlese–Tullgren apparatus. The density and richness of total fauna varied distinctly according to sites, sampling time and material sampled (soil and litter). 16,409 of fauna were recovered from soil and litter samples and the density of total fauna was 2,094 individuals m⁻² in the litter and 641 individuals m⁻² in the soil. The richness was 11.8 in the litter and 7.5 in the soil. The cacao agroforestry systems adopted for growing cacao in the southern Bahia region of Brazil have beneficial effects on the soil and litter faunal communities, and such systems of cacao cultivation could be considered as a conservation system for soil fauna. The development of a litter layer resulted in higher abundance and diversity of soil fauna.     

Perennial pigeonpea: a multi-purpose species for agroforestry systems

Perennial pigeonpea is receiving considerable attention in India as a multi-purpose species for agroforestry systems. Its multiple uses include food, fodder, manure and firewood. Data on perennial pigeonpea, together with relevant information on shorter-duration genotypes, are reviewed in this paper. Growth of perennial pigeonpea, like that of medium-duration grain types (150 to 190 days) in intercropping systems with cereals, is slow during the first 3 to 4 months. Therefore, it requires minimum sacrifice in terms of yield of annual crops in the system during the first year and offers many of the benefits of tree species in subsequent years. Total dry matter production potential of perennial pigeonpea in peninsular India is more than 15 t ha⁻¹ year⁻¹ consisting of about 2.0 t of grain, 3.0 t of leaf litter, 9.0 t of stems and 1.0 t of residue made up of podwalls and twigs. In addition, pigeonpea improves soil fertility by nutrient cycling and biological nitrogen fixation. Susceptibility of pigeonpea to diseases and negative effects on growth of annual crops are the potential constraints in the semi-arid tropics. Some pertinent areas for further research are proposed. Submitted as ICRISAT Journal Article No. 917 for ‘Agroforestry Systems’.     

Promising agroforestry systems in Venezuela

The main agroforestry systems in Venezuela are the multispecies plant associations in integrated coffee production system and the silvopastoral system. This paper describes the functional and structural aspects of these systems. The multilayered coffee production systems are practised mainly in the premontane moist forest of the Andes region, but are also found in other areas of the country. Various tree species are used for shade and as fence in big coffee plantations, whereas in small units with traditional production pattern, coffee is planted along with many other species, often constituting a 3–4 layer canopy. Available data are presented on the production as well as some socioeconomic aspects.The silvopastoral systems are found in the tropical dry forest (savannas) and in the very dry tropical forest of the semiarid zones of the country. A large number of trees and shrubs are found in these pastoral areas where they play both productive (fodder and feed) and service (shelter) roles.Although both these systems are practised over large areas of the country, practically no research has been done to improve them. In order to strengthen national capability to undertake such research, international support of cash and as well as technical advice is needed.

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Resumen Los principales sistemas agroforestales en Venezuela son el Sistema integrado de producción de café y el sistema silvopastoril. En el presente trabajo se describen aspectos funcionales y estructurales de esos sistemas. El sistema de producción multi-estratificado de café es practicado principalmente en el bosque húmedo premontano de la región andina, per también es frecuentemente observado en áreas del país. Diferentes especies de árboles son utilizados como sombra y como cercos vivos en las grandes plantaciones de café, mientras que en las pequenas unidades con un patrón de producción tradicional, el café es plantado junto con una gran diversidad de especies constituyendo un dosel vegetativo de 3–4 estratos.Información disponible sobre producción y algunos aspectos socio-económicos es presentada en el trabajo.Los sistemas silvopastoriles son encontrados en el bosque seco tropical (sabanas o llanos) y en el bosque muy seco tropical de las zonas semiaridas del país. Un gran número de árboles y arbustos se encuentran en esas áreas de pastoreo donde juegan un doble rol, producción (forraje ya alimento) y servicio (refugio y abrigo).Aunque ambos sistemas son practicados en grandes áreas del país, practicamente ninguna investigación se ha llevado a cabo para mejoralos. Con el objeto de fortalecer la capacidad en el país de llevar a cabo tal tipo de investigación, se hace necessario recursos economicós y asesaría técnica por parte de organizaciones internacionales.

     

Soil quality characteristics of traditional agroforestry systems in Mouzaki area,central Greece

Agroforestry Systems - Agroforestry systems (AFS) are characterized by growing trees and crops on the same area, aiming at sustainable production and better natural resources management, whilst...     

Temporal changes in soil carbon and nitrogen in west African multistrata agroforestry systems: a chronosequence of pools and fluxes

The conversion of forests to agroecosystems or agroforests comes with many changes in biological and chemical processes. Agroforestry, a tree based agroecosystem, has shown promise with respect to enhanced system nutrient accumulation after land conversion as compared to sole cropping systems. Previous research on tropical agroforestry systems has revealed increases in soil organic matter and total organic nitrogen in the short term. However, research is lacking on long-term system level sustainability of nutrient cycles and storage, specifically in traditional multi-strata agroforestry systems, as data on both the scope and duration of nutrient instability are inconclusive and often conflicting. This study, conducted in Ghana, West Africa, focused on carbon and nitrogen dynamics in a twenty-five year chronosequence of cacao (Theobroma cacao Linn.) plantations. Three treatments were selected as on-farm research sites: 2, 15 and 25-year-old plantations. Soil carbon (C, to a depth of 15 cm) varied between treatments (2 years: 22.6 Mg C ha⁻¹; 15 years: 17.6 Mg C ha⁻¹; 25 years: 18.2 Mg C ha⁻¹) with a significant difference between the 2- and 15- and the 2- and 25-year-old treatments (p < 0.05). Total soil nitrogen in the top 15 cm varied between 1.09 and 1.25 Mg N ha⁻¹ but no significant differences were noted between treatments. Soil nitrification rates and litter fall increased significantly with treatment age. However, photosynthetically active radiation (PAR) and soil temperature showed a significant decrease with age. No difference was found between decay rates of litter at each treatment age. By 25 years, system carbon sequestration rates were 3 Mg C ha⁻¹ y⁻¹, although results suggest that even by 15 years, system-level attributes were progressing towards those of a natural system.