BC-School of Environmental Studies
Permanent URI for this community
Browse
Browsing BC-School of Environmental Studies by Author "Bationo, A."
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item The African Network for Soil Biology and Fertility: New Challenges and Opportunities(Academy Science Publishers, 2004) Mugendi, D.N.; Bationo, A.; Kimetu, J.; Ikerra, S.; Kimani, S.; Odendo, M.; Silver, M.; Swift, M.J.; Sanginga, N.Soil fertility degradation has been described as the single most important constraint to food security in sub-Saharan Africa (SSA). Soil fertility decline is not just a problem of nutrient deficiency but also of 1)Inappropriate germplasm and cropping system design. 2) Interactions with pests and diseases. 3) The linkage between poverty and land degradation. 4) Often perverse national and global policies with respect to incentives, and 5) Institutional failures. Tackling soil fertility issues thus requires a long-term perspective and a holistic approach. The African Network for Soil Biology and Fertility (AfNet)of Tropical Soil Biology and Fertility institute of CIATwhose ultimate goal is to strengthen and sustain stakeholder capacity to generate, share and apply soil fertility management knowledge and skills to contribute to the welfare of farming communities is devoted to overcoming this challenge. This African-wide network has over 200 members from National Agricultural Research and Extension Services (NARES) and universities from vanous disciplines mainly soil science. social science and technology exchange. This paper is an highlight of AfNet's main activities which include: Network field research activities. information and documentation. training and capacity building.Item Available technologies to replenish soil fertility in East Africa(Springer Netherlands, 2007) Mugendi, D.N.; Okalebo, J. R.; Othieno, C. O.; Woomer, P. L.; Karanja, N. K.; Semoka, J.R.M.; Bekunda, M. A.; Muasya, R. M.; Bationo, A.; Mukhwana, E. J.Low inherent soil fertility in the highly weathered and leached soils largely accounts for low and unsustained crop yields in most African countries. But in particular, the major nutrients, nitrogen (N) and phosphorus (P), are commonly deficient in these soils. This scenario of nutrient depletion is reflected in food deficits and hence the food aid received continuously, specifically in sub-Saharan Africa. Undoubtedly, substantial efforts have been made in the continent to replenish the fertility of degraded soils in attempts to raise crop yields, towards self-sufficiency and export. Such efforts consist of applications of both organic and inorganic resources to improve the nutrient status of soils and enhanced nutrient uptake by crops, provided that soil moisture is adequate. Overall, positive crop responses to these materials have been obtained. Thus in the East African region, maize (staple) yields have been raised in one growing season from below 0.5 t/ha without nutrient inputs, to 3–5 t/ha from various nutrient amendments at the smallhold farm level. However, in spite of the positive crop responses to nutrient inputs, farmers are generally slow to adopt the soil fertility management technologies. In this paper we review the impact of some technologies, focussing the use of nutrient resources of different characteristics (qualities) in relation to improved crop yields, with an overall goal to enhance technology adoption. Thus, inorganic resources or fertilizers often give immediate crop responses, but their use or adoption is rather restricted to large-scale farmers who can afford to buy these materials. Organic resources, which include crop residues, water hyacinth and agroforestry shrubs and trees, are widely distributed, but they are generally of low quality, reflecting the need to apply large quantities to meet crop nutrient demands. Moreover, most organics will add N mainly to soils. On the other hand, phosphate rocks of varying reactivity are found widely in Africa and are refined elsewhere to supply soluble P sources. The recently developed soil fertility management options in East Africa have targeted the efficient use of N and P by crops and the integrated nutrient management approach. Some people have also felt that the repackaging of inputs in small, affordable quantities, such as the PREP-PAC described in this paper, may be an avenue to attract smallhold farmers to use nutrient inputs. Nonetheless, crop responses to nutrient inputs vary widely within and across agroecozones (AEZs), suggesting specificity in recommendations. We highlight this observation in a case study whereby eight soil fertility management options, developed independently, are being tested side- by-side at on-farm level. Farmers will be empowered to identify technologies from their own choices that are agronomically effective and economically friendly. This approach of technology testing and subsequent adoption isItem Soil Microbial Biomass Carbon and Nitrogen as Influenced by Organic and Inorganic Inputs at Kabete, Kenya(Springer Netherlands, 2007) Mugendi, D.N.; Baaru, M. W.; Bationo, A.; Verchot, L.; Waceke, W.Soil microbial biomass is the main driving force in the decomposition of organic materials and is frequently used as an early indicator of changes in soil properties resulting from soil management and environment stresses in agricultural ecosystems This study was designed to assess the effects of organic and inorganic inputs on soil microbial biomass carbon and nitrogen overtime at Kabete, Kenya. Tithonia diversifolia, Cassia spectabilis, Calliandra calothyrsus were applied as organic resources, and Urea as inorganic source. Soil was sampled at 0–10 cm depth before incorporating the inputs and every two months thereafter and at harvesting in a maize-cropping season. Soil microbial biomass carbon and nitrogen was determined by Fumigation Extraction method (FE) while carbon evolution was measured by Fumigation Incubation (FI) method. The results indicated a general increase in soil microbial biomass carbon and nitrogen in the season with the control recording lower values than all the treatments. Microbial biomass carbon, nitrogen and carbon dioxide evolution was affected by both quality of the inputs added and the time of plant growth. Tithonia recorded relatively higher values of microbial biomass carbon, nitrogen and carbon evolution than all the other treatments. A significant difference was recorded between the control and the organically treated soils at the of the season for the microbial biomass nitrogen and carbon dioxide evolution. Both the microbial biomass C and N showed a significance difference (P $⩽0.05) in the different months of the seasonItem Strategies for Maintenance and Improvement of Soil Productivity Under Continuous Maize and Beans Cropping System in the Sub-humid Highlands of Kenya: Case Study of the Long-Term Trial at Kabete(Dordrecht, 2012) Mugendi, D.N.; Kibunja, C. N.; Mwaura, F. B.; Gicheru, P. T.; Wamuongo, J. W.; Bationo, A.Inappropriate soil management practices are cited as the main causes of soil fertility decline of cultivated lands in sub-Saharan Africa (SSA). Small-scale farmers are faced with daunting challenges and limited opportunities for maintaining the productivity of their land due to low accessibility and affordability of agricultural inputs. In Kenya, a series of fertilizer trials conducted throughout the country in the 1990s, showed that nitrogen (N) and phosphorus (P) were deficient in 57% and 26% of the sites covered. The effect of continued cultivation with application of mineral and organic fertilizers on soil quality and crop yields was studied in a long-term field experiment at Kabete, in the highlands of Kenya, which was started in 1976. The area is sub-humid with an average bimodal rainfall of 980 mm and two cropping seasons per year. The treatments included: control (no-input); fertilizer nitrogen (N) and phosphorus (P) at 60 kg N/ha and 26 kg P/ha, and 120 kg N/ha and 52 kg P/ha; farmyard manure (FYM) at five (5) and ten (10) t/ha and farmyard manure (5 t/ha) combined with 60 kg N and 26 kg P/ha. For each treatment, crop residues were retained (+) or removed (−) in half of the plots. Maize and beans were planted during the long and short rain seasons, respectively. This paper presents a review of experimental results derived from the long-term experimental site at Kabete, Kenya over a period of 30 years. Results indicate that application of all inputs significantly (p = 0.05) improved maize yields over the control but there was no significant differences among the treatments. Cumulative use of FYM gave better yields than NP fertilizers but the combined use of FYM and inorganic fertilizers was the most economically and promising strategy for sustained soil crop yields A general decline in soil bio-physical properties was observed over time. Soil acidification, decline in soil organic carbon and nitrogen has been noted over time. Use of inorganic fertilizers without addition of FYM or crop residues led to loss of soil biodiversity. None of the strategies used have maintained carbon stocks at the initial level. Integrated use of farmyard manure and chemical fertilizers, combined with liming to reduce soil acidification and use of deep rooted rotational crops should be recommended to sustain soil productivity under continuous cultivation.