The purpose of this study was to characterize the soil organic carbon dynamics associated with four land-uses (cropland, grassland, shrubland, and forestland) in the upper Blue Nile Basin of the Ethiopian Highlands. We collected diverse biophysical data to allow spatial variability of soil organic carbon and factors contributing to this variation to be determined statistically, and used well established simulation models to interpret the data, predict long-term carbon dynamics and determine the potential for improvements in soil quality and mitigation of greenhouse gas emissions. The spatial variation in soil organic carbon in the 0-20 cm soil depth was significant across study areas (P<0.01, 21.6 g kg-1-37.8 g kg-1), and between land-uses (P<0.05, 27.9 g kg-1 in cropland and 43.0 g kg-1 soil in forestland). In a multiple linear regression model, among the 11 explanatory variables used, four (total nitrogen, shrubs, trees and land use) showed a significant positive effect (P<0.01), while three (impact of grazing, impact of erosion and clay) showed a significant negative effect (P<0.01). Simulations using the assumption of steady state to estimate carbon dynamics suggested that plant inputs from croplands are generally lower than grass or shrublands, resulting in build-up of recalcitrant organic matter in shrublands compared to grass or croplands. Erosion results in a decline in both the absolute and relative amounts of carbon in recalcitrant pools, but the more active pools remained unchanged, meaning that the overall activity of soil organic matter is increased when the soil is eroded, and it becomes more difficult to sequester soil carbon. More rapid decrease in soil organic carbon is likely to be due to increased erosion, persistent removal of organic materials, grazing pressures, and higher rate of decompositions in cropland and grazing land-uses. Conversion to shrubland shows high potential to quickly restore eroded soils and build up a pool of recalcitrant soil carbon, suggesting that management of land using periodic 20 year exclosures, preventing cropping and grazing and allowing shrubland succession, could be beneficial in restoring degraded soils. Simulations using a calibration approach, rather than assuming steady state, corroborated these findings, suggesting that after 30 years of current management, croplands will deplete soil organic carbon by 5.6, 7.1 and 7.2 tha-1, and grasslands by 3.5, 3.9 and 2.7 tha-1, while shrublands will build-up soil organic carbon by 0.6, 0.1 and 1.3 tha-1 at study sites. At one study site, forests, will further increase soil organic carbon by 6.7 tha-1 after 30 years. The significant positive impact of shrubs and trees on soil organic carbon suggests the need to focus on introduction of agroforestry systems in crop and grasslands. © 2015 Elsevier B.V.
Tag: agricultural land
Meat and milk production scenarios and the associated land footprint in Kenya
Increasing demands for meat and milk in developing countries and the associated production growth are driving the expansion of agriculture at the expense of environmental conservation and other land uses. While considerable attention has been directed at improving crop yields to alleviate the pressure on land, there has been far less attention on the implications of the expected intensification of livestock production. Here, we present and analyse the land availability and land footprints of livestock intensification for five scenarios representing various degrees of intensification of meat and milk production by cattle, sheep, goats and camels in arid, semi-arid and humid production systems in Kenya. The first three scenarios are defined by increasing levels of input and management, ranging from low (scenario S1), intermediate (S2) to high (S3) input feed crop cultivation and livestock production. Reference scenario S1 has production practices and output of meat and milk similar to current production practices. In scenarios S2 and S3, the total land used for livestock production remains the same as in S1. Two additional scenarios, S4 and S5, explore opportunities for lessening environmental pressure through reduction of the land footprint of meat and milk production. For each scenario, we quantify the potential availability of grassland and cropland for meat and milk production by cattle, sheep, goats and camel in the arid, semi-arid and humid production systems. A resource use indicator, land footprint (ha), is used to assess changes in land use associated with livestock production. We estimate that the potential increase in production due to intensification from scenario S1 to S2 is 51% for milk and 71% for meat. The potential increase due to improving production from scenario S1 to S3 is 80% for milk and 113% for meat. The area of grazing land, as a percentage of the total potentially available grazing land, decreases from 10% to 6% as productivity increases from scenario S1 to S5. Cropland usage increases from 4% in scenario S1 to 11% in scenario S5. Reduced land demand in scenarios S4 and S5 indicates the possibility that intensification may help reduce the pressure on land and hence promote environmental conservation. Overall, the results suggest that it is possible to increase production to meet increasing demands for meat and milk while also gaining land for environmental conservation through intensification. Realizing the potential presented by the intensification scenarios will be contingent upon successfully establishing and operationalizing enabling policies, institutional arrangements and markets and ensuring that relevant information, services, inputs, and other essential requirements are available, accessible and affordable to herders and farmers. © 2016 Elsevier B.V.
Modeling the Impact of Canal Blocking on Water Table Dynamics and Carbon Emissions in Drained Peatlands
Peatlands are significant carbon sinks, storing vast amounts of organic carbon in their waterlogged soils However, when they are drained for agricultural or other land-use purposes, the natural hydrological balance is disrupted. This disruption allows the soil organic carbon to decompose, leading to peat subsidence and the release of carbon emissions into the atmosphere and waterways. Extensive drainage systems exacerbate this process, transforming peatlands from globally significant carbon sinks into one of the leading contributors of greenhouse gas emissions from the landbased sector.
Scrutinizing Urbanization in Kathmandu Using Google Earth Engine Together with Proximity-Based Scenario Modelling
‘Urbanization’ refers to the expansion of built-up areas caused by several factors. This study focuses on the urbanization process in Kathmandu, the capital of Nepal. Supervised classification was conducted in Google Earth Engine by using Landsat data for years 2001, 2011 and 2021. The random forest classifier with 250 trees was used for classification to generate land-cover map. A land-cover map of 2021 was used as base map in the InVEST tool for scenario modelling. An accuracy assessment with 20% of sample points was conducted with different metrics, such as overall accuracy, kappa coefficient, producer accuracy, and consumer accuracy. The results show an increment of built-up areas by around 67 km2 over 20 years in a centrifugal pattern from the core district, converting agricultural and forest land. ‘Forest’ is still dominant land-use class, with an area of 177.97 km2. Agricultural land was highly converted to urban area. The overall accuracy of this classification process ranged 0.96–1.00 for different years. The scenario modelling further elaborated an amiability of drastic shift in land-use classes to ‘built-up’, especially forest and agriculture, by around 33 km2 and 66 km2, respectively. This study recommends the consideration of ecological approaches during the planning process.
Agricultural Land Soil and Water Conservation Techniques in Pagar Alam
Pagar Alam farmers actively maintain soil fertility and use Soil and Water Conservation (SWC) techniques in agricultural land management, particularly in upland areas. Short-term soil fertility restoration is focused on the use of chemical fertiliser. Technique options and suitability for preventing erosion and landslide to ensure long-term sustainability are severely limited.
Farm size limits agriculture’s poverty reduction potential in Eastern India even with irrigation-led intensification
Millions of people living in the Eastern Gangetic Plains (EGP) of India engage in agriculture to support their livelihoods yet are income poor, and food and climate insecure. To address these challenges, policymakers and development programs invest in irrigation-led agricultural intensification. However, the evidence for agricultural intensification to lift farmers’ incomes above the poverty line remains largely anecdotal. The main objective of this study is to use a large household survey (n = 15,572; rice: 8244, wheat: 7328; 2017/18) to assess the link between agricultural intensification and personal daily incomes from farming (FPDI) in the rice-wheat systems of the EGP – the dominant cropping system of the region. We use the Intensification Benefit Index (IBI), a measure that relates farm size and household size to FPDI, to assess how daily incomes from rice-wheat production change with irrigation-led intensification across the EGP. Relative to the international poverty line of 1.90 Purchasing Power Parity (PPP)$ day−1 and accounting for variations in HH size in the analysis, we found that small farm sizes limit the potential for agricultural intensification from irrigation to transform the poverty status of households in the bottom three quartiles of the IBI. The estimated median FPDI of households with intensified systems in the bottom three quartiles is only 0.51 PPP$ day−1 (a 0.15 PPP$ gain). The median FPDI increases to 2.10 PPP$ day−1 for households in the upper quartile of the IBI distribution (a 0.30 PPP$ gain). Irrigation-led agricultural intensification of rice-wheat systems in the EGP may provide substantial benefits for resilience to climatic change and food security but achieving meaningful poverty reduction will require complementary investments. Transforming the poverty status of most smallholder farmers in the EGP requires diversified portfolios of rural on- and off-farm income-generating opportunities. While bolstering food- and climate security, agronomic intervention programs should consider smallholders’ limited monetary incentives to invest in intensification. Irrigation-led agricultural intensification programs and policies should explicitly account for the heterogeneity in household resources, irrigation levels, and degree of dependence on agricultural income.
Profitability of Gliricidia-Maize System in Selected Dryland Areas of Dodoma Region, Tanzania
Declining soil fertility and climatic extremes are among major problems for agricultural production in most dryland agro-ecologies of sub-Saharan Africa. In response, the agroforestry technology intercropping of Gliricidia (Gliricidia sepium (Jacq.)) and Maize (Zea mays L.) was developed to complement conventional soil fertility management technologies. However, diversified information on the profitability of Gliricidia-Maize intercropping system in dryland areas is scanty. Using data from the Gliricidia and maize models of the Next Generation version of the Agriculture Production Systems sIMulator (APSIM), this study estimates the profitability of the Gliricidia-Maize system relative to an unfertilized sole maize system. Results show significant heterogeneity in profitability indicators both in absolute and relative economic terms. Aggregated over a 20-year cycle, Gliricidia-Maize intercropping exhibited a higher Net Present Value (NPV = Tsh 19,238,798.43) and Benefit Cost Ratio (BCR = 4.27) than the unfertilized sole maize system. The NPV and BCR of the latter were Tsh 10,934,669.90 and 3.59, respectively. Moreover, the returns to labour per person day in the Gliricidia-Maize system was 1.5 times those of the unfertilized sole maize system. Sensitivity analysis revealed that the profitability of the Gliricidia-Maize system is more negatively affected by the decrease in output prices than the increase in input prices. A 30% decrease in the former leads to a decrease in NPV and BCR by 38% and 30%, respectively. Despite the higher initial costs of the agroforestry establishment, the 30% increase in input prices affects more disproportionally unfertilized sole maize than the Gliricidia-Maize system in absolute economic terms, i.e., 11.1% versus 8.8% decrease in NPV. In relative economic terms, an equal magnitude of change in input prices exerts the same effect on the unfertilized sole maize and the Gliricidia-maize systems. This result implies that the monetary benefits accrued after the first year of agroforestry establishment offset the initial investment costs. The Gliricidia-Maize intercropping technology therefore is profitable with time, and it can contribute to increased household income and food security. Helping farmers to overcome initial investment costs and manage agroforestry technologies well to generate additional benefits is critical for the successful scaling of the Gliricidia-Maize intercropping technology in dryland areas of Dodoma, Tanzania.
Modeling interventions to reduce deforestation in Zambia
Agriculture faces tremendous pressure to supply both growing and wealthier populations with more food, fiber, and fuel, while recognizing the limits of agricultural ecosystems. But it remains unclear whether it is possible to increase agricultural and food production without increasing deforestation and associated greenhouse gas emissions. The objective of this study was to advance the understanding of landscape-level implications of sustainable intensification of agriculture on forest conservation in Zambia. Sustainable intensification aims to increase agricultural yields and reduce deforestation. Miombo woodlands, a dry forest ecosystem common throughout the region, are the dominant biome in much of Zambia, and they are suitable for the production of charcoal, a commonly used cooking fuel among urban households. We used participatory system dynamics modeling to examine the drivers of deforestation in two provinces in Zambia. We modeled four scenarios to examine their effects on reducing deforestation over a 50-year simulation period: (i) an increase in maize yield from adoption of SI practices, and (ii) occasional moderate and severe drought events, (iii) adoption of efficient charcoal cookstoves, and (iv) full electrification. We found no effects of adoption of sustainable intensification practices on agricultural encroachment into forested ecosystems. The clearing of forested land for agriculture was found to be largely driven by the rising demand for wood fuels for cooking and heating, particularly charcoal in urban areas. Charcoal was increasingly dominant as a driver of deforestation in both provinces such that changes in land practices and economic returns to farmers are unlikely to reveal measurable changes in land use. The findings have implications for the development of integrated approaches to address the challenges of food and energy insecurity, as well as for national-level policies aimed at climate change mitigation and reducing greenhouse gas emissions. This study provides a unique and innovative approach to integrating social and biophysical/ecological data through the application of system dynamics modeling. Furthermore, the study contributes to the literature on the environmental implications of agricultural land use and the drivers of deforestation.
Evaluating woody species composition and regeneration in controlled and free grazing systems for scaling up agroforestry in the highlands of northern Ethiopia
Understanding the performance of agroforestry woody species in controlled and free grazing systems is crucial for scaling up agroforestry practices. The objective of this study was to identify and evaluate the determinants of agroforestry woody species composition and regeneration in free and controlled grazing systems in the Ethiopian highlands. Household and field surveys were conducted on 83 and 171 households selected from controlled grazing (CG) and free grazing (FG) systems, respectively. Woody species performance was compared between the two grazing systems using independent T-test. Seemingly unrelated regression (SUR) was used to identify the factors determining woody species density/abundance, diversity and regeneration. Most trees were grown for fuel wood and timber rather than for fodder. CG users owned more diversified species and abundant regenerates and mature trees/shrubs than FG users. The SUR results showed that herd size, farmland size, fencing, plantation of seedlings, education, wealth, grazing system, farmland distance from homestead and slope were the major factors affecting the composition and regeneration of species. Specifically the SUR results per-household indicated that woody species regeneration was highly affected by grazing system. Fencing is the common underlying factor positively affecting species diversity, regeneration and density of mature trees. Homestead distance from road and number of planted seedlings significantly affected density of regenerates and mature trees. Density of mature trees and species diversity were significantly affected by agroecology and slope. Woody species diversity was significantly affected by education, wealth, farmland size and project participation. Our findings revealed that the scaling up of woody species in agroforestry requires not only CG and favorable agroecology but also matching of agroforestry options with household and farmland characteristics.
Trees on Farms as a Nature-based Solution for Biodiversity Conservation and Restoration
Rwanda has diverse habitats and ecosystems that range from humid montane forests to savannahs, lakes, rivers, farmland and wetlands all of which support a wide range of biodiversity. This biodiversity supports livelihoods and provides critical ecosystem services such as water, control of soil erosion and flood control as well as climate change mitigation.