Knowledge for Development

Feature articles

Are soil and water conservation technologies a buffer against production risk in the face of climate change?

This brief is based on a study that investigates the risk implications of various soil and water conservation technologies for crop production in Ethiopia’s Nile River Basin. The analysis identifies technologies that increase and decrease crop production risk—with risk defined as the degree of yield variability—for the purpose of isolating which technologies are best suited to particular regions and agroecological zones. These results could be used to improve the geographical targeting of soil conservation techniques as part of efforts to promote farm-level adaptation to climate change.Authors: K. Edward, C. Ringler, M. Yesuf & E. Bryan, IFPRI brief & Ethiopia Development Research Institute, 2009


Use of inorganic fertilizers in Uganda

Improving agricultural productivity is vital for poor rural households in Uganda to meet their food security needs and to promote sustained increases in income. Inorganic fertilizer can be a powerful productivity enhancing input. While Uganda has one of the highest soil nutrient depletion rates in the world, it has one of the lowest rates of annual inorganic fertilizer application – only 1.8 kg per hectare. The World Bank calculated that the value of replacing these depleted soil nutrients could be 20 percent of average rural Ugandan household income. Promoting fertilizer use is therefore crucial to sustainably increase agricultural productivity in Uganda. This brief explores the economics of fertilizer use by smallholder farmers in Uganda, the determinants of fertilizer use, and options for government action.Author: Namaazi, J. IFPRI brief, 2009


Re-coupling the carbon and water cycles by Natural Sequence Farming

Reference: International Journal of Water 2010 - Vol. 5, No.4 pp. 386 – 395, by: Duane Norris, Peter Andrews The techniques of Natural Sequence Farming (NSF) were developed during hands-on management of degraded farmland in the Upper Hunter Valley region of Australia. Early settlement of the continent by people with European cultural assumptions disrupted established interactions of water, soil, and plants resulting in lost fertility. Moreover, agricultural practices such as clearing, burning, ploughing, draining, and irrigation, have implications for global warming. Soils hold twice as much carbon as the atmosphere, and three times as much as vegetation. But carbon in exposed soil oxidises, releasing CO2 into the atmosphere. NSF is designed to restore ecosystem functions by re-coupling the carbon and water cycles. This is a valid technique for dryland regions around the world.


How do satellite images and airborne imagery relate to agriculture and forestry?

Satellite and aerial imagery play a significant role in modern day agricultural production and forest related activities. T he primary value of satellite and airborne imagery to agriculture and forestry is two-fold. Firstly, imagery provides valuable information that is useful for planning and managing the potential crop output, in a sustainable way. Imagery results in more sustainable food production. Secondly, imagery enables the gathering of knowledge about agriculture and forestry through local to regional to global scales. That knowledge enables a better understanding of overall production factors, but also contributes toward risk management decisions and supports predictive modelling of food supply and consumption. This article gives a thorough account of the applications of satellite imagery and GIS used in the agriculture and forestry sectors.(Vector1media, 13 May 2011)


Research on satellite imagery aims to advance sustainable agriculture

The excessive use of irrigation water has resulted in serious environmental concerns in many dry-land countries, where rising demand has deteriorated groundwater resources, depleted aquifers, and accelerated saltwater intrusion. Scientists in Spain are working on new technologies to classify and monitor irrigated crops with a goal of promoting sustainable agricultural practices. The field studies the researchers designed were to evaluate the potential of multispectral reflectance and seven vegetation indices in the visible and near-infrared spectral range for discriminating and classifying bare soil and several horticultural irrigated crops. The research is the first step of a broader project with the overall goal of using satellite imagery with high spatial and multispectral resolutions for mapping irrigated crops. (American Society for Horticultural Science via Physorg, 1/4/2011)


Soil science, indigenous knowledge and sustainable intensification: Implications for smallholder farming systems

By Walter M Simonson In his article, Oluwatoyin Kolawole highlights key issues on the peculiarities of Africa’s soils and how they affect agricultural production. He argues that because of the very high diversity and spatial heterogeneity in soil type and quality across sub-Saharan Africa, a one-size-fits-all solution is inappropriate to address Africa’s divergent soil problems. Kolawole uses a number of research initiatives on integrated soil fertility management to show that Western science and local/indigenous knowledge are not mutually exclusive in driving sustainable management practices and improving yields on small farms. 


Sustainable Intensification and Conservation Agriculture

Amir Kassam in his lead article argues that the no-till farming system involving soil cover and crop diversification, known as Conservation Agriculture (CA), is fundamentally changing farming practices and management of the land resource base, the landscape and the environment. As a proponent of this approach, Kassam notes that CA enhances ecosystem services and resilience, and offers additional economic and environmental benefits that are difficult or impossible to mobilize with conventional tillage agriculture. In his view, CA fits within the sustainable intensification paradigm which when defined in its broadest sense, encompasses production and ecological dimensions, the biological products produced and utilized by consumers and with minimum food waste, as well as the human and economic dimensions of socio-cultural aspirations, organizations and social equity and economic growth.According to Kassam, CA is not intensification in the classical sense of greater use of inputs but rather the intensification of knowledge, skills and management practices and the complementary judicious use of other inputs. He sees the new challenge for science and policy in the 21st Century as being able to produce more from less and with minimum damage and to rehabilitate degraded and or abandoned lands while conserving and optimizing the use of the remaining water and biodiversity resources. CA is now being practiced on 125 million hectares (about 9% of cropland) across all continents, and approximately 50% lies in the developing countries, including in African countries, namely Kenya, Lesotho, Malawi, Mozambique, Tanzania, Zambia and Zimbabwe. Kassam believes that CA can contribute to the goal of sustainable intensification, but more research and extension effort is needed to inform policy formulation and development strategies. 


Soil Fertility – Paradigm shift through collective action

Countries in Sub-Saharan Africa (SSA) are among those with the highest rates of nutrient depletion (Stoorvogel and Smaling, 1990; Smaling, 1993; Smaling et al., 1997). A few highly influential studies of land degradation in Africa have provided substantial evidence. The International Centre for Soil Fertility and Agricultural Development (IFDC) estimated that Africa loses 8 million metric tons of soil nutrients per year and over 95 million ha of land have been degraded to the point of greatly reduced productivity (Henao and Baanante, 2006). At least 85% of African countries are estimated to have nutrient mining of above 30 kg of nutrients per ha per year and 40% of countries experience losses of over 60 kg of nutrients per ha per year (World Bank, 2006; Henao and Baanante, 2006). Equally the Global Assessment of Soil Degradation (GLASOD) reports that degraded soils amount to about 494 millions ha in Africa (Oldeman et al. 1991; Batjes 2001). It is also estimated that 65 per cent of SSA's agricultural land is degraded because of water and soil erosion, chemical and physical degradation (Oldeman et al. 1991; UNEP 1992; Scherr 1995).


Tropical soils with focus on West Indian Soils

Weathering or rock disintegration is rapid in the tropics due to high temperatures and leaching of the released nutrient elements caused by high rainfall. This leaves a highly resistant residue poor in plant nutrients, from which the soil develops. Tropical soils are infertile and considered fragile because the small amount of nutrients that is mostly concentrated on the soil surface can be easily lost. Since the farmers have little resources with which to maintain the soil fertility, they practise fallow but there are problems with this method as the fallow periods have become progressively shorter. In the Caribbean, although the land area is comparatively relatively small, the geology, rocks and soils are highly variable and almost every important grouping of soils is represented. Geologically the area is not very old so weathering, leaching and soil formation are not very advanced and the resulting soils are not as fragile and prone to rapid degradation as elsewhere in the tropics. As a whole, the soils are more resilient than in other tropical areas.