Raising the productivity of smallholder farms under semi-arid conditions by use of small doses of manure and nitrogen: a case of participatory research

Participatory on-farm trials were conducted for three seasons to assess the benefits of small rates of manure and nitrogen fertilizer on maize grain yield in semi-arid Tsholotsho, Zimbabwe. Two farmer resource groups conducted trials based on available amounts of manure, 3 t ha-1 (low resource group) and 6 t ha-1 (high resource group). Maize yields varied between 0.15 t ha-1 and 4.28 t ha-1 and both absolute yields and response to manure were strongly related to rainfall received across seasons (P<0.001). The first two seasons were dry while the third season received above average rainfall. Maize yields within the seasons were strongly related to N applied (R2=0.77 in season 1, and R2=0.88 and 0.83 in season 3) and other beneficial effects of manure, possibly availability of cations and P. In the 2001-2002 season (total rainfall 478 mm), application of 3 and 6 t ha-1 of manure in combination with N fertilizer increased grain yield by about 0.14 and 0.18 t ha-1, respectively. The trend was similar for the high resource group in 2002-2003 although the season was very dry (334 mm). In 2003-2004, with good rainfall (672 mm), grain yields were high even for the control plots (average 1.2 and 2.7 t ha-1). Maize yields due to manure applications at 3 and 6 t ha-1 were 1.96 and 3.44 t ha-1, respectively. Application of 8.5 kg N ha-1 increased yields to 2.5 t ha-1 with 3 t ha-1 of manure, and to 4.28 t ha-1 with 6 t ha-1 of manure. In this area farmers do not traditionally use either manure or fertilizer on their crops, but they actively participated in this research during three consecutive seasons and were positive about using the outcomes of the research in future. The results showed that there is potential to improve livelihoods of smallholder farmers through the use of small rates of manure and N under semi-arid condition

Strategies for recruitment and retention of teen mothers in a program to prevent repeat pregnancy

Background: We describe challenges to recruitment and retention of teen mothers in a study to prevent repeat teen pregnancies, and strategies used to overcome them. Methods: We documented recruitment efforts, the teens who were retained at each stage of the intervention and changes to strategies. Results: Challenges to recruitment and retention were related to lifestyles, immaturity, and competing demands, among others. Successful strategies included bus advertisements, early pairing of teens with mentors, using electronic media, convenient meeting times with a meal, providing child care, transportation vouchers and immediate incentives. Conclusions: This study highlights impediments to teen mother research recruitment and retention, and the value of emerging technologies and strong bonding relationships early in the intervention to maximize recruitment and retention

Productivity and residual benefits of grain legumes to sorghum under semi-arid conditions in southwestern Zimbabwe

The productivity and residual benefits of four grain legumes to sorghum (Sorghum bicolor) grown in rotation were measured under semi-arid conditions over three cropping seasons. Two varieties of each of the grain legumes; cowpea (Vigna unguiculata); groundnut (Arachis hypogaea); pigeon pea (Cajanus cajan); Bambara groundnut (Vigna subterranea), and sorghum were grown during the first season. The same experiment was implemented three times in different, but adjacent fields that had similar soil types. At the end of the season the original plots were split in two and residues were either removed or incorporated into the subplots. The following season sorghum was planted in all subplots. In 2002/03 (314 mm rainfall) cowpeas produced the largest dry grain yield (0.98 and 1.36 t ha-1) among the legumes. During the wettest year (2003/04, 650 mm rainfall) groundnut had the highest yields (0.76 to 1.02 t ha-1). In 2004/05 (301 mm rainfall) most legume yields were less than 0.5 t ha-1, except for pigeon pea. Estimates of % N from N2-fixation from the legumes were 15-50% (2002/03), 16-61% (2003/04) and 29-83% (2004/05). Soil water changes during the legume growth cycle were proportional to varietal differences in total legume biomass. Sorghum grain yield after legumes reached up to 1.62 t ha-1 in 2003/04 compared with 0.42 t ha-1 when following sorghum. In 2004/05, sorghum yields after legumes were also higher (up to 1.26 t ha-1) than sorghum after sorghum. Incorporation of crop residues had no significant effect on sorghum yield. Beneficial effect of legumes on yields of the subsequent sorghum crop were more readily explained by improvements in soil nitrogen supply than by the small observed changes in soil water relations. Our results demonstrate clear potential benefits for increasing grain legume cultivation in semi-arid environments through the use of improved germplasm, which also gave substantial increases in subsequent sorghum productivity (up 200% in a wet season and 30-100% in a dry season), compared with an unfertilized sorghum crop following sorghum

Dynamics of FitzHugh-Nagumo excitable systems with delayed coupling

Small lattices of $N$ nearest neighbor coupled excitable FitzHugh-Nagumo systems, with time-delayed coupling are studied, and compared with systems of FitzHugh-Nagumo oscillators with the same delayed coupling. Bifurcations of equilibria in N=2 case are studied analytically, and it is then numerically confirmed that the same bifurcations are relevant for the dynamics in the case $N>2$. Bifurcations found include inverse and direct Hopf and fold limit cycle bifurcations. Typical dynamics for different small time-lags and coupling intensities could be excitable with a single globally stable equilibrium, asymptotic oscillatory with symmetric limit cycle, bi-stable with stable equilibrium and a symmetric limit cycle, and again coherent oscillatory but non-symmetric and phase-shifted. For an intermediate range of time-lags inverse sub-critical Hopf and fold limit cycle bifurcations lead to the phenomenon of oscillator death. The phenomenon does not occur in the case of FitzHugh-Nagumo oscillators with the same type of coupling.Comment: accepted by Phys.Rev.

Capital Account Policies, IMF Programs and Growth in Developing Regions

This paper develops an adaptive learning model under uncertainty that examines evolution of capital account polices over time and across developing regions. In the framework, countries' past experiences and IMF programs influence policymakers' beliefs about the impact of capital account liberalization on growth, under the 'Mundell's trilemma constraint. The model, calibrated to data for Africa, Latin America and developing Asia, reflects relatively well capital account policies adopted in 1980-2010. It shows that even more developed countries with liberalized capital accounts may revert to controls under large output shocks. The outcomes of capital account switches are better and closer to policymakers' expectations in countries with the IMF programs, underscoring the role of complementarity of policies

Climatic Forcing of Plio-Pleistocene Formation of the Modern Limpopo River, South Africa

Understanding the evolution of river systems in southern Africa is fundamental to constrain the evolution of landscape and sediment dispersal patterns. It is widely considered that the upper Zambezi River was connected with the Limpopo River during the Cretaceous, forming what was then the largest river in Africa. Crustal flexure during the Paleogene severed the upper Zambezi drainage from the Limpopo, setting the framework of the modern Zambezi and Limpopo River systems. We present first evidence—based on heavy-mineral assemblages from cores drilled offshore of the Limpopo River mouth and samples collected in different reaches of the modern Limpopo River, integrated with magnetic susceptibility, detrital-zircon geochronology, and geomorphological analysis—suggesting that the current Limpopo River formed recently in the Plio-Quaternary. Plio-Quaternary climate change is envisaged to have controlled the recent dynamics of river drainage and consequent distribution of sediment loads, as observed in many other transcontinental rivers worldwide

Hepatitis C Infection Among Injecting Drug Users in England and Wales (1992–2006): There and Back Again?

Changes in hepatitis C virus (HCV) prevalence from 1992 to 2006 were examined by using 24,311 records from unlinked anonymous surveillance of injecting drug users in England and Wales. Bayesian logistic regression was used to estimate annual prevalence, accounting for changing recruitment patterns (age, gender, injecting duration, geographic region, interactions) and the sensitivity and specificity of different oral fluid testing devices. After controlling for these differences, the authors found that the adjusted HCV prevalence decreased from 70% (95% credible interval: 62, 78) in 1992 to 47% (95% credible interval: 43, 51) in 1998 before rising again to 53% (95% credible interval: 48, 58) in 2006. Women injecting drug users had a higher HCV risk than did men (odds ratio = 1.50, 95% credible interval: 1.31, 1.73). Two regions (London and North West) had a markedly higher HCV prevalence than did the rest of England and Wales. Among individuals who had injected for less than 1 year, the adjusted HCV prevalence in 2006 was higher than that in 1992 (28% vs. 19%, respectively). HCV infection can be prevented. The public health challenge in England and Wales is to increase action in order to regain a downward trend in HCV risk and the benefit that has been lost since 1998

Optimizing Livelihood and Environmental Benefits from Crop Residues in Smallholder Crop-Livestock Systems in Southern Africa. Series Paper Number 11

Sustainable forms of intensification are needed to address the low and stagnant production of farming systems in southern Africa. More efficient use of crop-livestock interactions can contribute to this; in this context the effective use of crop residues is becoming increasingly important and also contested. Crop residues left on the field for mulching are expected to bring long-term environmental benefits but when fed to livestock they provide farmers with short-term livelihood benefits. This study aims at better understanding the diversity of farming systems and uses of crop residues, in particular the trade-offs in using the residues for soil amendment versus livestock feed. It is part of a global comparison with sites along a human and livestock population density gradient across sub-Saharan Africa and South Asia. This southern Africa study represents the most extensive case of semi-arid areas with lowest biomass production. Three sites were compared, at different levels of agricultural intensification, extent of crop-livestock integration and use of crop residues. 1. Mzimba in Northern Malawi – intensified crop oriented production. 2. Nkayi in southwest Zimbabwe – integrated crop-livestock systems. 3. Changara in Tete province in Central Mozambique – extensive crop-livestock farming. Across the three sites, crop residues are clearly needed as livestock feed. In Nkayi and Changara low crop yields and low biomass production against the existing demand from livestock prevents farmers from using residues for purposes other than livestock feed. The practice of collecting and kraal feeding residues in Nkayi illustrates that the pressure on residues is at a level where farmers start privatizing residues in order to ensure their individual benefits. When feeding crop residues in the kraal, farmers also increase the amount of manure for soil fertility improvement. Even in Mzimba, with higher residue production and lower livestock ownership, very few farmers retain the residues to achieve real impact on soil health. Although farmers see soil fertility as a critical constraint, they have limited residues to spare for mulching. The trade-offs of reallocating crop residues from livestock feed to mulching for soil amendment will be high as long as alternative feed technologies and access to input and output markets are not developed. The trade-offs will be lower in areas with higher biomass production and less competition with livestock. Technical options need to increase biomass on existing croplands, addressing feed shortages and the need for soil amendment concurrently. Viable institutional structures and appropriate policies need to support this intensification processes through better access to inputs, knowledge and markets. The pathways for sustainable intensification and more efficient crop residue utilization need to be developed within the local context. We found strong growth potential for livestock-oriented agricultural development in extensive areas (Changara), strengthening crop and livestock integration to support intensification in areas like Nkayi, and enhancing crop-livestock integration for more efficient resource utilization where biomass is less limiting (Mzimba)

The Real Exchange Rate and Growth in Zimbabwe: Does the Currency Regime Matter?

Zimbabwe faces growth and external competitiveness challenges, as indicated by its low trend growth and investment, declining share in the world exports, high current account deficits, and external debt. The stock-flow approach to the equilibrium exchange rate reveals that the real exchange rate experienced periods of sizeable overvaluation, both prior to the 2008 economic collapse and under the current multicurrency regime. While overvaluation hampers GDP growth, as well as growth and employment in export sectors, we have not found that undervaluation would raise it. Replacing the multicurrency regime anchored in the US$ by the South African rand as the sole transaction currency would help reduce overvaluation and stimulate exports and growth. Under any currency regime, Zimbabwe needs to adhere to sound macroeconomic policies, avoid overspending on public wages, and create environment conducive for investment.http://deepblue.lib.umich.edu/bitstream/2027.42/132981/1/wp1081.pd