An adequate supply of micronutrients is essential for balanced plant growth. In Africa, micronutrient constraints are known to restrict crop productivity and impair human welfare and health. We analyzed a total of 816 topsoil and 796 subsoil samples from Sub-Saharan Africa, to provide baseline information on their readily available Al, B, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn concentrations. This work builds on previous global micronutrient surveys. The studied soils were low in hot water-extractable B, acid ammonium acetate-EDTA-extractable micronutrients, and potentially harmful metals. In comparison with tentative critical level values, B, Cu, Zn, Mo, and Fe in a considerable number of samples seemed to be at a low level for crop production. Apart from Al, Mo, V, Pb, and Cr, readily available element concentrations were higher in topsoil than subsoil. Concentrations of harmful metals (Cd, Ni, Pb) and of Mn and Mo were enriched in cultivated soils in comparison with semi-natural sites. Among the 11 Reference Soil Groups represented in the study, Arenosols were discernible as poor in Cr, Cu, and Fe. Other significant differences in microelement concentrations between soil groups were found only for Ni and V.
Tag: food supply
The potential of indigenous fruit trees: results of a survey in Kitui District, Kenya
A semi-structured questionnaire survey was conducted [date not given] at 6 divisions (Central, Chuluni, Kabati, Mutito, Mutomo and Yatta) in Kitui District, a semi-arid area of Kenya. Farmers (n=7-9) were asked on the identification, propagation, management, preference and market value of indigenous tree species in the area. A total of 62 wild species was identified in farmlands and woodlands. The top 10 priority species of the farmers (in descending order) were Vitex payos, Tamarindus indica, Sclerocarya birrea, Adansonia digitata, Azanza garckeana, Vangueria rotundata, Berchemia discolor, Carissa edulis, Ximenia caffra, Balanites aegyptica, and Loranthus uluguense. Marketing survey revealed that seven of the top 10 species (Adansonia digitata, Azanza garckeana, Berchemia discolor, S. birrea, T. indica, V. payos and X. caffra) already have commercial potentials as they are sold in local markets. The survey also revealed that indigenous knowledge existed on managing indigenous fruit trees species such as spot slashing around individual trees to reduce competition from less favoured trees, pruning trees, and supporting young regenerants. The constraints identified by farmers that limit planting and management of indigenous fruit tree species are presented. Recommendations made from the survey are also presented.
Should REDD+ fund ‘sustainable intensification’ as a means of reducing tropical deforestation?
Over the last 50 years, the global population has doubled. Despite this, food production has more than kept pace, resulting in a 24% increase in per capita world food production and a 40% reduction in food prices in real terms. While some progress has been made towards lowering the proportion of people suffering from chronic hunger from 20 to 16%, the absolute number of chronically hungry has actually increased to more than 900 million. Until recently, conventional wisdom was that while global food production was sufficient to meet demand, the main problem was one of distribution. This conclusion was reassessed towards the end of the 2000s, when the effect of changing diets in developing nations was taken into account, which indicated that food production will need to increase 70% to meet demand in 2050. A recent analysis relating calorie and protein consumption to GDP puts this even higher at 100–110%. These projections have prompted a number of high-profile reports analyzing the global food production system, generally concluding that gains are likely to come from a mix of new applications of existing knowledge, new technologies, and development and implementation of appropriate economic and social policies, and sustainable intensification on existing crop area.
Which urban agriculture conditions enable or constrain sustainable food production?
Urban agriculture (UA) has been adopted as a strategy for food security in urban areas. This study identified the conditions for development of UA through a systematic review of UA case studies. It classified the enabling and constraining conditions within the three compositional elements of UA – necessity, ability, and opportunity – and determined the primary and secondary conditions for UA design by the country income group. The following conditions are required for both high-income and low/ middle-income countries: Motivation/public awareness; labour/human resources; policy and institutional infrastructure; social capital; and arable land and resources for farming. Agricultural education/training and research and technical development are needed for low and middle-income countries as the key secondary conditions. In high-income countries, a lack of farmers’ knowledge and urban development are the main challenges to UA implementation. Therefore, the research findings could be meaningful evidence for making decisions and designing UA policies for sustainable food production.
No-till and mulching enhance energy use efficiency and reduce carbon footprint of a direct-seeded upland rice production system
Sustainability of conventional agricultural production systems is threatened by triple challenges of energy and environmental crises, deteriorating natural resources bases, and declining farm profitability. Current agricultural management practices (energy-intensive, inefficient external and natural input use, and crop biomass burning) are negatively impacting the ecosystem services which are the principal drivers for food security and human survival. Hence, there is a need to shift from unsustainable production practices to cleaner production systems. Energy use, carbon footprint (CF), and economic sustainability are important indicators of any clean production systems. Thus, a hypothesis was formulated that no-till (NT) cultivation along with mulching can provide an environmentally clean crop production practice that can enhance energy use efficiency, economic profitability, and reduce the CF. Therefore, the present experiment was conducted for four consecutive years (2012–15) to evaluate the energy budget, CF, and economics of NT along with bio-mulching for a cleaner upland rice production system. The experiment comprised of two tillage practices i.e., conventional tillage (CT) and NT in main plots and four bio- mulches in subplots i.e., rice straw mulch (RSM), Gliricidia sepium mulch (GLM), brown manuring mulch (BMM) of cowpea (Vigna unguiculata), and no mulch (NM) as a control. Results revealed that the adoption of NT curtailed energy use by 48.50%, specific energy by 49.63%, CF by 16.48%, and cost of cultivation by 35% in addition to enhancing energy use efficiency and benefit to cost ratio in comparison to CT. It was also observed that mulching, particularly the BMM, boosted the energy use efficiency, economic productivity, net returns, and benefit to cost ratio over NM. The results suggested that NT with BMM is an environmentally clean production technology to enhance the energy use efficiency, besides reducing the CF of direct-seeded upland rice production system in the Eastern Himalayas and similar eco-regions of the world.