177,977 research outputs found
Improved fallows in Eastern Zambia: history, farmer practice and impacts
No full text"The decline in soil fertility in smallholder systems is a major factor inhibiting equitable development in much of sub-Saharan Africa. Some areas fallow in order to strength soil fertility for later planting, but as populations increase, demand follows and continuous cropping becomes the norm and there is a reduction in yields. This case study summarizes the development of improved tree fallows by researchers and farmers in eastern Zambia to help solve the problem of poor soil fertility. Many farmers are finding that by using improved fallows, they can substitute relatively small amounts of land and labor for cash, which they would need to buy mineral fertilizer. The study has three phases: the historical background (phase 1); an assessment of problems, description of the technology, and how it was developed (phase 2); and how the improved fallows practices were disseminated and spread (phase 3). This paper will describe each phase, the goals, and results." Authors' AbstractSouthern Africa, africa south of sahara, Crop yields,
Factors influencing adoption of agroforestry among smallholder farmers in Zambia
No full textAgroforestry technologies have been extensively researched and introduced to smallholder farmers in Zambia for over two decades. Despite the research and extension effort over this period, not many farmers have adopted these technologies. The purpose of this paper is to determine why agroforestry technologies are not being taken up by examining factors that influence the adoption of agroforestry practices. Based on data obtained from 388 farming households, statistical analysis show an association between adoption of both improved fallows and biomass transfer technologies with knowledge of the technology, availability of seed, and having the appropriate skills. In addition some household characteristics are found to be linked to the incidence of adoption. However, the strength of association between these variables is low, giving an indication that there might be other factors at play limiting agroforestry adoption. It is anticipated that these findings will point to other areas beyond the household and community level that need further exploration in order to understand factors limiting agroforestry adoption.Agroforestry adoption, smallholder farmers, limitations to adoption, chi-square tests of independence analysis, Zambia, Agricultural and Food Policy, Community/Rural/Urban Development, Crop Production/Industries, Environmental Economics and Policy, Land Economics/Use,
Developments in the use of EISCAT for interplanetary scintillation
No full textThe antennas of EISCAT have been used for interplanetary scintillation (IPS) studies of the solar wind for many years. The main science found from these studies is obtained through the cross-correlation of signals from antennas having the longest baseline, providing more accurate information on the different solar wind streams which may be present in the line of sight. The development of dual-frequency IPS observations between the 1.4 GHz receivers at the remote sites and Tromso, has allowed the use of the EISCAT Svalbard Radar for IPS, increasing the available baselines to the extent that three solar wind streams can sometimes be identified in the cross-correlation functions. A weak-scattering model incorporating three possible solar wind streams and dual observing frequencies is discussed and some results presented. A recent study found that the current sampling bandwidth limits the sensitivity of IPS observations at EISCAT. Methods of increasing the sensitivity, and the results of trials, are discussed
Simultaneous interplanetary scintillation and Heliospheric Imager observations of a coronal mass ejection
No full textWe describe simultaneous Interplanetary Scintillation (IPS) and STEREO Heliospheric Imager (HI) observations of a coronal mass ejection (CME) on 16 May 2007. Strong CME signatures were present throughout the IPS observation. The IPS raypath lay within the field-of-view of HI-1 on STEREO-A and comparison of the observations shows that the IPS measurements came from a region within a faint CME front observed by HI-1A. This front may represent the merging of two converging CMEs. Plane-of-sky velocity estimates based on time-height plots of the two converging CME structures were 325 kms?1 and 550 kms?1 for the leading and trailing fronts respectively. The plane-of-sky velocities determined from IPS ranged from 420 ± 10 kms?1 to 520 ± 20 kms?1. IPS results reveal the presence of micro-structure within the CME front which may represent interaction between the two separate CME events. This is the first time that it has been possible to interpret IPS observations of small-scale structure within an interplanetary CME in terms of the global structure of the event
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dry-season sesbania fallows and their influence on nitrogen availability and maize yields in Malawi
No full textNitrogen deficiency is widespread in southern Africa, but inorganic fertilizers are often unaffordable for
smallholder farmers. Short-duration leguminous fallows are one possible means of soil fertility restora-
tion. We monitored preseason topsoil (0 to 20 cm) ammonium and nitrate, fallow biomass production
and grain yields for three years in a relay cropping trial with sesbania [Sesbania sesban (L.) Merr.] and
maize (Zea mays L.). Sesbania seedlings were interplanted with maize during maize sowing at 0, 7400
or 14,800 trees ha –1 , in factorial combination with inorganic N fertilizer at 0 or 48 kg N ha –1 (half the
recommended rate). After maize harvest, fallows were allowed to grow during the seven-month dry season,
and were cleared before sowing the next maize crop. Both sesbania fallows and inorganic N fertilizer
resulted in significantly greater (P < 0.01 to 0.05) preseason topsoil nitrate-N than following unfertilized
sole maize. In plots receiving no fertilizer N, preseason topsoil inorganic N correlated with maize yield
over all three seasons (r 2 = 0.62, P < 0.001). Sesbania fallows gave significantly higher maize yields
than unfertilized sole maize in two of three years (P < 0.01 to 0.05). Sesbania biomass yields were
extremely variable, were not significantly related to sesbania planting density, and were inconsistently
related to soil N fractions and maize yields. Short-duration fallows may offer modest yield increases under
conditions where longer duration fallows are not possible. This gain must be considered against the loss
of pigeonpea (Cajanus cajan L. Millsp) harvest in the similarly structured maize-pigeonpea intercrop
common in the region
Dry-season sesbania fallows and their influence on nitrogen availability and maize yields in Malawi
No full textNitrogen deficiency is widespread in southern Africa, but inorganic fertilizers are often unaffordable for
smallholder farmers. Short-duration leguminous fallows are one possible means of soil fertility restora-
tion. We monitored preseason topsoil (0 to 20 cm) ammonium and nitrate, fallow biomass production
and grain yields for three years in a relay cropping trial with sesbania [Sesbania sesban (L.) Merr.] and
maize (Zea mays L.). Sesbania seedlings were interplanted with maize during maize sowing at 0, 7400
or 14,800 trees ha –1 , in factorial combination with inorganic N fertilizer at 0 or 48 kg N ha –1 (half the
recommended rate). After maize harvest, fallows were allowed to grow during the seven-month dry season,
and were cleared before sowing the next maize crop. Both sesbania fallows and inorganic N fertilizer
resulted in significantly greater (P < 0.01 to 0.05) preseason topsoil nitrate-N than following unfertilized
sole maize. In plots receiving no fertilizer N, preseason topsoil inorganic N correlated with maize yield
over all three seasons (r 2 = 0.62, P < 0.001). Sesbania fallows gave significantly higher maize yields
than unfertilized sole maize in two of three years (P < 0.01 to 0.05). Sesbania biomass yields were
extremely variable, were not significantly related to sesbania planting density, and were inconsistently
related to soil N fractions and maize yields. Short-duration fallows may offer modest yield increases under
conditions where longer duration fallows are not possible. This gain must be considered against the loss
of pigeonpea (Cajanus cajan L. Millsp) harvest in the similarly structured maize-pigeonpea intercrop
common in the region
Logistic modelling of smallholder livestock farmers’ adoption of tree-based fodder technology in Zimbabwe
No full textBased on field data collected from 131 small scale dairy farmers that were randomly selected from four agro-ecological zones, this study assessed the potential of adoption of fodder bank technology as a means for improving livestock production and income generation for smallholder farmers in Zimbabwe. Using a logit modelling approach, it also identified the drivers of adoption of the technology by analysing the influence of household characteristics and ecological factors on farmers’ decision to adopt the technology. The model correctly predicted 75% of observed adoption and non-adoption by farmers. Results reveal that dairy herd size, land holding size, membership of dairy association and agro-ecological potential are the key factors influencing farmers’ adoption of fodder bank. Age, sex, household size and educational level of farmers play lesser role. Male and female farmers were equally likely to take up and practice fodder bank if they are given equal access to information and incentives. The study recommends farmer-led extension approaches where farmers who possess certain key characteristics should constitute the initial group for disseminating information regarding the technology in rural communities. The results highlight the importance of access to dairy product markets as a driver for the adoption of fodder banks. It is recommended that forging a strategic partnership with the Dairy Development Programme (DDP) will offer high potential for enhancing the scaling up of the adoption and impact of fodder bank technology in the country.Livestock Production/Industries, Research and Development/Tech Change/Emerging Technologies,
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