Restoring fertility to soils after topsoil stripping for brick production in Bangladesh through harnessing agro-ecosystem waste-streams.

Lead Research Organisation: Queen's University of Belfast
Department Name: Sch of Biological Sciences

Abstract

The striping of topsoil is very common in the agronomic regions abutting urban centres in Bangladesh. As urban centres have been growing exponentially in Bangladesh, particularly around the mega-city of Dhaka, the focus of this study, there are concerns regarding food security due to loss of agricultural land, and the degradation of surrounding agronomic land that has had its topsoil removed. Estimates for the amount of land impacted in peri-urban zones of the Indian-sub-continent through topsoil stripping are 10%. Crop yields from the subsoils left after topsoil removal, even with excess fertilization, decrease by over 50%, impacting subsistence farmers. As clay from soil is the only source of building material, it is unlikely that the practice of stripping soils for brick production will stop or decline in Bangladesh, thus there is a great need to find ways of restoring fertility to impacted soils. We proposed to do this by harnessing nutrient rich agronomic waste streams that are common in Bangladesh agri-ecosystems to rapidly restore impacted soil to full cropping potential. These nutrient rich waste streams include manures, oil cake, rice husks & biomass ash. The grant proposal plans to optimise how these waste streams can be applied to subsoils to fully restore soil sustainability, at a low cost to the farmer, & thereby enhancing the food security of the region.

The proposal has two stages. The first is to characterize the nutrient content and quantity of waste streams flowing through Bangladeshi substance rice farming communities and then maximize ways in which to redirect these waste-streams back to the land. The second is to trial, through both wet and dry season rice cultivation, across 9 geographically separated Bangladeshi villages, the utility of these wastes for building up soil health and increasing rice yields, testing common Bangladeshi rice cultivars.

Technical Summary

The soils of the peri-urban regions of Bangladesh are being stripped of topsoil to provide the raw material (clay) for brick production. The proposal will investigate how restoration of topsoil stripped soils can be used to enhance rice crop yields in Bangladesh. This will be achieved sustainably through harnessing of local agri-ecosystem waste streams as fertilizers. Nutrient rich waste-streams include cattle manure, oil cake (the by-product of oil extraction from seeds), rice husks and ash from biomass burning (both domestic & industrial). This will supply nitrogen, carbon, phosphorus and silicon, base cations to counteract subsoil acidity, plus micro-elements, to restore soil fertility. Rice cropping systems, both wet season and ry season production, will be optimized.

The proposal looks at the quantity and quality of waste available throughout Bangladesh and the impact it has on rice yield and on restored subsoil health. Soils and rice will be characterised for their nutritional content, while state-of-the-art NGS approaches, supported by visual assessment, will be used to characterise pathogen infection and insect predation to ensure altering fertilization/manuring practice maintains a healthy soil and plant microflora, leading sustainably to enhanced yields.

Planned Impact

This proposal is designed to improve the lot of the subsistence farmers of Bangladesh by giving them sustainably higher yields of rice on soils that have had their topsoil removed for brick production. We predict that return normal soil fertility can be achieved following the research proposed here, improving yield by >50% compared to what, in effect, subsoils can produce. The project aims to connect agroecosystem biomass waste streams to optimise the return to fertility of impacted soils. If these waste streams are redirected back to the land enhanced yields of rice can be obtained sustainably, giving more wealth and resources to subsistence rice farmers throughout Bangladesh. It will also provide greater food security to the region in general. This recycling waste streams approach developed for Bangladesh can be used throughout the world where topsoil loss is prevalent (through soil erosion as well as brick production), adapting to local rice growing management and societal practices.

Subsistence farmers will be involved with the project, leading to their farms being in effect demonstration sites, hopefully leading ground up dissemination. National level Bangladesh dissemination will occur through meetings to discuss the grants outputs with officials and NGOs involved with land management and farming. Wider dissemination will be arranged through media (television, radio newspapers, blogs etc.). Through these approaches we would aim for the widest possible impact to deliver better livelihoods to subsistence farmers whose security degraded through subsisting on a declining soils resource.

The project will train both Bangladesh and UK based scientists in complementary skills, including soil management, analytical chemistry, molecular biology and agricultural economics. This will lead to capacity building in both countries involved, training scientists to improve the lot of the agricultural poor.

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