HORTINLEA - SP3 Soil Fertility Management


Overall aim of the project is provision of knowledge on the current status of soil fertility management, and identification of possible constraints for vegetable production in the peri-urban area of Nairobi due to mineral nutrients, soil organic matter contents and heavy metals. Data will be collected for various African indigenous vegetables (AIV) including amaranth, African night shade, African kale, spider plant and cowpea, and compared to data from maize as a standard species. The data will form a basis for the development of a catalogue of recommendations to improve soil fertility, nutrient efficiency and vegetable nutritional quality in vegetable production systems through agronomic measures. Specifically, the project will address three objectives:
1) Analysis of the current status of nutrient management and of crop-specific mineral nutrient requirements.
To achieve this object, the variability of soil nutrient availability and associated plant nutrient status, and species-specific nutrient balances will be assessed for AIV at the scale of farms and individual fields. Root traits related to nutrient acquisition from soil, and species-specific responses to differences in soil nutrient availability will be identified in field and pot experiments on research station. This knowledge will provide a basis for the generation of integrated nutrient management strategies for AIV for the purpose of increasing yields (outputs 2 and 4). Nutrient balances and management strongly impact on biodiversity, soil fertility, soil carbon sequestration, and greenhouse gas emissions, both, via direct effects e.g. of reactive nitrogen compounds, and via indirect effects on plant productivity and thus, competition between agricultural and natural landscapes (DeFries and Rosenzweig, 2010). Therefore, the project will also contribute to the assessment of ecological sustainability of vegetable production systems (output 5).
2) Analysis of the current status of soil organic matter (SOM) management and of crop-specific effects on SOM content
To achieve this object, the variability of SOM contents and causes underlying this variability will be assessed at the scale of farms and individual fields. The mass and composition of plant-derived organic carbon (C) input from above-ground and below-ground organs into the soil will be measured, and humification coefficients of plant-derived C will be quantified. These data will provide a basis for the generation of integrated soil fertility management strategies for AIV for the purposes of increasing yields (outputs 2 and 4), and the assessment of ecological sustainability of vegetable production systems (output 5).
3) Analysis of the current status and sources of heavy metal (HM) contamination of vegetables, and of crop-specific plant traits regulating HM contamination
To achieve this object, HM availability in soil and irrigation water will be measured at the scale of individual fields and related to contents in edible organs of AIV. Surface contamination and internal accumulation of samples taken in fields, stores and markets will be compared to identify sources of HM pollution in urban and peri-urban horticultural systems (output 4). Species-specific pathways of HM contamination and plant traits regulating HM accumulation will be identified in field and pot experiments. This knowledge will provide a basis for the development of guidelines to prevent excessive exposure of consumers with toxic metals, and thus will contribute to improve nutritional value and quality of AIV (output 2).

Principal Investigators
Engels, Christoph Prof. Dr. (Details) (Plant Nutrition)

Duration of Project
Start date: 07/2013
End date: 12/2018

Last updated on 2020-22-10 at 00:05