| 1. |
- Alavaisha, Edmond, 1988-
(författare)
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Agricultural expansion impacts on wetland ecosystem services from Kilombero Valley, Tanzania
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Land use change has major impact on the world’s wetland ecosystems and biodiversity. The motivation behind this change has been to increase agricultural production, often resulting in negative effects on water quality and soil fertility. Tanzania has carried out a large expansion and intensification of agriculture under the Kilimo kwanza (First agriculture) initiative which has triggered the need for better knowledge on land use change effects and associated ecosystem functioning. This thesis considers small-scale irrigation schemes to understand the effects of agriculture expansion and farming practices on nutrients, water quality and ecosystem services (ES) in Kilombero Valley, Tanzania. The study approach is multidisciplinary involving interviews, remote sensing, geographical information system techniques, and in-field soil and water ecological sampling. The major land use change in the valley during the last three decades was transformation from forest, bushland and grassland into cultivated land. The rate of change was faster adjacent to irrigation schemes and most changes occurred downstream irrigation canals, close to the floodplain. Irrigation and fertilization contributed to soil carbon and nitrogen accumulation in crop fields, which both declined in concentration with depth into the soil. However, such management practices and agricultural land expansion had impacts on several ES – especially water quality in streams. Streams surrounded mainly by cultivated land, as well as downstream areas, had lower water quality compared to streams with less settlement, more natural vegetation and upstream areas. Furthermore, when evaluated, macroinvertebrates indices were found to be a good indicator of water quality and a complement to chemical and physical water analysis. Irrigation farming produced more food compared to rainfed farming, and also other ES such as flood regulation, erosion control and several cultural services, depending on the river discharge. The thesis shows the importance to use irrigation/fertilization management to enhance soil fertility and preserve soil structure, but also the need for proper irrigation management to prevent flooding and erosion, conserve natural vegetation, and protect water quality. To enhance nature conservation, preserve biodiversity and secure future supply of ES in the valley, investment in irrigation infrastructures should be done at small-scale to mitigate the large-scale exploitation of Kilombero wetland.
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| 4. |
- Barron, Jennie
(författare)
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Berken plow and intercropping with pigeon pea ameliorate degraded soils with a hardpan in the Ethiopian highlands
- 2022
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Ingår i: Geoderma. - : Elsevier BV. - 0016-7061 .- 1872-6259. ; 407
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Tidskriftsartikel (refereegranskat)abstract
- Closing the yield gap and enhancing efficiency in rainfed maize production systems in Ethiopia requires urgent action in increasing the productivity of degraded agricultural land. The degradation of land through continuous compaction and decline in the organic matter has resulted in a wide-spread formation of a hardpan that restricts deep percolation, prevents plant root development, and, ultimately can lead to increased erosion. Studies exploring practical low-cost solutions to break the hardpan are limited in Ethiopia. The main objective was to evaluate soil mechanical (i.e. modified plow or Berken plow) or biological intervention (i.e. intercropping with pigeon pea) effectiveness to enhance soil water management and crop yield of rainfed maize systems whilst reducing soil erosion and runoff. Five farm fields, each including four plots with different tillage treatments, were monitored during two rainy seasons in 2016 and 2017. The treatments were: (i) farmers practice under conventional (CT) tillage; plots tilled three times using an oxen driven local plow Maresha, (ii) no-till (NT), (iii) Berken tillage (BT), plots tilled three times using an oxen pulled Berken plow, and (iv) biological (CT + Bio), taprooted pigeon pea intercropped with maize on plots conventionally tilled. Results showed that mean tillage depth was significantly deeper in the BT (28 cm) treatment compared to CT and CT + Bio (18 cm) treatments. Measured soil penetration resistance significantly decreased up to 40 cm depth under BT and maize roots reached 1.5 times deeper compared to roots measured in the CT treatment. Under BT, the estimated water storage in the root zone was estimated at 556 mm, 1.86 times higher compared to CT, 3.11 times higher compared to NT and 0.89 times higher compared to CT + Bio. The positive effects on increased water storage and root development resulted in an average increase in maize grain (i.e. 15%, 0.95 t ha- 1) and residual above ground biomass (0.3%, 6.4 t ha- 1) leading to a positive net benefit of 138 USD ha- 1 for the BT treatment compared to the CT treatment. The negative net benefit obtained under CT and CT+Bio was mainly related to the high labor cost related to plowing, weeding, planting, and fertilizer application whilst in the NT this was related to the significantly lower maize yields. The positive effects in the BT treatment, and to some extent the CT+Bio treatment show great potential for smallholder rainfed maize systems where degraded soils with hardpans and high variability in rainfall prevail.
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| 5. |
- Barron, Jennie
(författare)
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Building climate resilience in degraded agricultural landscapes through water management: A case study of Bundelkhand region, Central India
- 2020
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 591
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Tidskriftsartikel (refereegranskat)abstract
- Rainfall variability and water scarcity continue to hamper the food and income security of smallholder farming systems in poverty-affected regions. Innovations in soil and water management, especially in the drylands, are critical for meeting food security and water productivity targets of Agenda 2030. This study analyzes how rainfed agriculture can be intensified with marginal impact on the landscape water balance. The impact of rainwater harvesting structures on landscape hydrology and associated agricultural services was analyzed in the semi-arid Jhansi district of Bundelkhand region in central India. The Parasai-Sindh pilot watershed was subjected to a 5-year (2012-2016) monitoring of rainfed system improvements in water availability and crop intensification due to surface water storage (haveli system), check dams, and field infiltration structures. Hydrological processes were monitored intensively to analyze the landscape's water balance components. Rainwater harvesting (RWH) structures altered the landscape's hydrology, limiting average surface runoff from 250 mm/year to 150 mm/year over the study period. Groundwater levels increased by 2-5 m (m), alleviating water scarcity issues of the communities in recurring dry years. Nearly 20% of fallow lands were brought under cultivation. Crop yields increased by 10-70% and average household income increased from US$ 960/year to US $ 2700/year compared to that in the non-intervention landscape. The combined soil-water-vegetation efforts strengthened water resilience and environmental systems in agricultural landscape.
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| 6. |
- Barron, Jennie
(författare)
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Building climate resilience in rainfed landscapes needs more than good will
- 2021
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Ingår i: Frontiers in Climate. - : Frontiers Media SA. - 2624-9553. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- Rainfed smallholder farming is particularly vulnerable to climate change, which can greatly exacerbate existing poverty and livelihood challenges. Understanding the complexity of the systems that connect the environment, society and people can help us to reduce this vulnerability and increase the resilience of communities and households to climate perturbations. In recent years, resilience theory has proven a useful approach for exploring the complexity of development challenges. As a result, there has been an increase in the development of tools and frameworks for assessing resilience. Despite this increased focus, there is no consistent use of the resilience concept in development practice and little evidence as to the benefits of using the tools. This paper aims to bridge theory and practice by coupling research on resilience with its application in the international development field. The specific hypothesis we explore is if and how rural livelihoods build resilience toward increased climatic variability in already degraded agro-ecological landscapes? We present a resilience framework with indicators to assess the extent of community resilience to climate change through improved local agricultural production and natural resources management. Primary and secondary landscape and community data, together with development of participatory watershed action plans were used to populate 16 indicators in a resilience framework baseline for the two rainfed dominated watersheds in Ethiopia and Ghana respectively. Given community awareness of the challenges related to the watershed natural resources, local agriculture and extreme weather, the communities were very willing to develop action plans to improve their management of natural resources and build climate resilience. Nevertheless, our analysis of the watershed action plans revealed that strengthening resilience through local action alone, would likely not be sufficient to meet all climate -livelihood challenges identified. To address severity and recurrence of climate change related disturbances, such as droughts, floods and disease in poverty-affected rural communities, the capacity to improve resilience will depend on external factors, in addition to inherent action. New knowledge, infrastructure and social security mechanisms, including insurance and emergency assistance need to added to build resilience for poverty-affected communities in degraded watersheds. We conclude there are also challenges in the use of resilience framework for development and climate-action related to rural poverty affected and degraded livelihood systems. Populating complex social–environmental systems will also need further development, to understand progress in resilience building under changing climate. Special attention to systemic indicators that describe the coupling and interdependencies of social-ecosystem factors will be critical to take action.
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| 7. |
- Barron, Jennie
(författare)
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Business model scenarios and suitability: smallholder solar pump-based irrigation in Ethiopia. Agricultural Water Management – Making a Business Case for Smallholders.
- 2018
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Rapport (refereegranskat)abstract
- This report outlines a business model approach to assessing the feasibility and for encouraging investment in smallholder solar pump irrigation. It also proposes a new methodology for mapping the suitability of solar energy-based irrigation pumps. The proposed business model framework and the methodology for suitability mapping are applied to Ethiopia as a case study, based on data from existing case studies and reports. A brief analysis outlines the regulatory and institutional context for investment in solar pump irrigation, and the ways in which it both constrains and attempts to support investment. The report identifies and outlines three business model scenarios that present opportunities for investing in smallholder solar pump-based irrigation, which would contribute towards sustainable intensification for food and nutrition security. The business model scenarios are based on the value proposition of supplying water to smallholder farmers for irrigated agricultural production. Analysis of potential gains and benefits suggests that direct purchase of solar pumps by farmers is feasible, and that out-grower schemes and pump supplier options with bundled financing offer promising solutions. The potential constraints that different investors may face in up-scaling the business models are also discussed, particularly within institutional, regulatory and financial contexts. The report provides development actors and investors with evidence-based information on the suitability and sustainability of solar pump irrigation in Ethiopia, as well as suggestions for helping to enable smallholders to invest in individually-owned, smallholder photovoltaic (PV) solar pumps.
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| 8. |
- Barron, Jennie
(författare)
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Challenges in reanalysis products to assess extreme weather impacts on agriculture: Study case in southern Sweden
- 2022
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Ingår i: PLOS climate. - : Public Library of Science (PLoS). - 2767-3200. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- The incidence of dry or wet day sequences has a great influence on crops management and development. The lack of spatialized observed data with appropriate temporal resolution to investigate the changes that has occurred during the last century regarding the length and frequencies of those sequences has led to reliance on reanalysis products. However, the question can be raised about the suitability of those products when evaluating such climate indices and their impacts on crop production. Different products are here investigated to evaluate how the succession of dry and wet days are depicted in Sweden. Results show that reanalysis product tends to overestimate the number of wet days and wet periods and underestimate dry periods. We also showed clearly that the frequency and intensity of dry and wet spells returned can differ widely between products. For instance, number of dry spell events can range from 1 to 11 over the same decade for two different products. This paper does not aim to classify the RPs regarding their goodness or efficiency but try to highlights the divergence between them in representation of spells which could generate substantial differences in climate impact analysis in agricultural modeling.
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| 9. |
- Barron, Jennie, et al.
(författare)
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Coping with Rainfall Variability : Dry Spell Mitigation and Implication on Landscape Water Balances in Small-scale Farming Systems in Semi-arid Niger
- 2010
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Ingår i: International Journal of Water Resources Development. - : Informa UK Limited. - 0790-0627 .- 1360-0648. ; 26:4, s. 543-559
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Tidskriftsartikel (refereegranskat)abstract
- Rainfall variability and inherent dry spells are a reality with severe implications for smallholder agro-ecosystems in semi-arid Sahel. To increase both on- and off-farm biomass production and productivity is challenging with these climate-induced temporal and spatial variations of water. This paper tests the idea that increased vegetation through tree cover may impact water balance in a water-stressed landscape: South-east Niger. Local rainfall data, farming systems data and a landscape water-modelling tool (ArcSWAT) are used. Four production domains (conventional or fertilized combined with millet crop or millet crop plus trees) were assessed for long-term yield and landscape water balance impacts. The dry-spell analysis shows a frequency of dry spells less than 14 days is in the order of one to two dry-spell events per season in 7 years out of 10 years. The occurrence has increased between 1960 and 2004, despite a slight recovery of total annual rainfall amounts since the severe droughts of the 1980s. Results of modelled millet yields and landscape water balances suggest that options exist to enhance landscape productivity. With marginal inputs of fertilizer, millet yields increased fivefold to 2.0-2.4tha-1, and water productivity improved from 6,000 to 12,000m3 actual evapotranspiration (ETa) t-1 grain, to an improved 1,700-3,000m3 ETa t-1 grain. In addition, 10% tree cover in combination with fertilized millet increased yield with marginal or no impact on water partitioning and flows in the landscape. The policy opportunities are complex and urgently needed in view of increased rainfall variability due to expected climate change. To develop sustainable pathways in these landscapes dominated by poor smallholder framers requires water managers to be more innovative and go beyond water resources alone.
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| 10. |
- Barron, Jennie
(författare)
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Deep Tillage Improves Degraded Soils in the (Sub) Humid Ethiopian Highlands
- 2019
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Ingår i: Land. - : MDPI AG. - 2073-445X. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Intensification of rainfed agriculture in the Ethiopian highlands has resulted in soil degradation and hardpan formation, which has reduced rooting depth, decreased deep percolation, and increased direct runoff and sediment transport. The main objective of this study was to assess the potential impact of subsoiling on surface runoff, sediment loss, soil water content, infiltration rate, and maize yield. Three tillage treatments were replicated at five locations: (i) no tillage (zero tillage), (ii) conventional tillage (ox-driven Maresha plow, up to a depth of 15 cm), and (iii) manual deep ripping of the soil's restrictive layers down to a depth of 60 cm (deep till). Results show that the posttreatment bulk density and penetration resistance of deep tillage was significantly less than in the traditional tillage and zero-tillage systems. In addition, the posttreatment infiltration rate for deep tillage was significantly greater, which resulted in significantly smaller runoff and sedimentation rates compared to conventional tillage and zero tillage. Maize yields were improved by 6% under deep tillage compared to conventional tillage and by 29% compared to no tillage. Overall, our findings show that deep tillage can be effective in overcoming some of the detrimental effects of hardpans in degraded soils.
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