MAIZE YIELD ESTIMATION IN KENYA USING MODIS

Abstract. Monitoring staple crop production can support agricultural research, business such as crop insurance, and government policy. Obtaining accurate estimates through field work is very expensive, and estimating it through remote sensing is promising. We estimated county-level maize yield for the 37 maize producing countries in Kenya from 2010 to 2017 using Moderate Resolution Imaging Spectroradiometer (MODIS) data. Support Vector Regression (SVR) and Random Forest (RF) were used to fit models with observed county level maize yield as a function of vegetation indices. The following five MODIS vegetation indices were used: green normalized difference vegetation index, normalized difference vegetation index, normalized difference moisture index, gross primary production, and fraction of photosynthetically active radiation. The models were evaluated with 5-fold leave one year out cross-validation. For SVR, R2 was 0.70, the Root Mean Square Error (RMSE) was 0.50 MT/ha and Mean Absolute Percentage Error (MAPE) was 27.6%. On the other hand for RF these were 0.69, 0.51 MT/ha and 29.3% respectively. These results are promising and should be tested in specific applications to understand if they are good enough for use

Proton nuclear magnetic resonance study of water + t-butyl alcohol, water + t--butylamine and water + t-butyl alcohol + t--butylamine mixtures

Hydroxyl-proton chemical shifts for water and t-butyl alcohol in water + t-butyl alcohol mixtures with 8 mol% t-butyl alcohol, and the average hydroxyl and amino proton chemical shift for water + t-butylamine mixtures, have been determined at 200 MHz for four temperatures (263, 278, 298 and 313 K) as a function of composition. Further measurements have been made for water + t-butyl alcohol + t-butylamine ternary mixtures at 310 K over the complete mole fraction range at 60 MHz. Variations in solvent composition have little effect on the resonance for the methyl protons of the cosolvent, but the signal for the hydroxylic protons is substantially influenced. The water proton resonance initially shifts to higher frequencies (low fields) as the cosolvent is added to water, and the shift to higher frequency is strongly temperature dependent, the effect being greatly enhanced at lower temperatures. As the proportion of cosolvent increases the hydroxyl proton signals in the water + t-butyl alcohol system and the average proton signals in water + t-butylamine mixtures shift to lower frequency (high field). (Received November 22, 2001; revised July 4, 2002) (Bulletin of The Chemical Society of Ethiopia: 2002 16 (2): 187-198

Vibrational spectra of t-butyl alcohol, t-butylamine and t-butyl alcohol + t-butylamine binary liquid mixtures

Raman and FT-IR absorption spectra of t-butyl alcohol and t-butylamine pure components have been recorded in the liquid state in the region of 400-4000 cm-1. The data obtained have been used to propose complete vibrational assignments for each of the liquid component and the structural features are discussed. Additionally, the Raman and infrared spectra of the binary liquid mixtures for the t-butyl alcohol/t-butylamine system have also been recorded. The variations in frequency shifts, intensities and line widths are discussed with a view to understanding the origin of such variations. KEY WORDS: Infrared and Raman spectra, Binary solution, t-Butanol, t-Butylamine  Bull. Chem. Soc. Ethiop. 2003, 17(2), 211-218

Ecosystem services and drivers of change in Nyando floodplain wetland, Kenya

Papyrus wetlands in East Africa play a vital role in supporting livelihoods of people living around them. Although, subject to natural fluctuations and threats by anthropogenic activities, little is known about historical changes in wetland functions and services, or their present status. We focused on Nyando wetland on the eastern shores of Lake Victoria, Kenya. Three sites in the wetland were identified for assessment of history and current status. Changes during the past fifty years were assessed through participatory exercises with local communities and a review of published work. To establish the current status, we used field surveys and transect walks. Results showed that the wetland is important for hydrological and also ecological functions, which depend on the connectivity of the wetland with river and lake. The major direct drivers of change were hydrological regimes and livelihood activities. The main indirect driver of change was population growth, which leads to more pressure on wetland resources. Provisioning services are important in Nyando wetland but are generated at the expense of regulating services. Hydrology and livelihoods are strongly interlinked as flooding limits access to the wetland. Understanding the historical changes in wetland functions and services is important for rural communities, policy makers and for wetland managers in guiding, planning and wetland management.Key words: Papyrus wetland, wetland ecosystem services, drivers of change, community perception, Nyando wetland

Phagocytosis of Plasmodium falciparum ring-stage parasites predicts protection against malaria.

Ring-infected erythrocytes are the predominant asexual stage in the peripheral circulation but are rarely investigated in the context of acquired immunity against Plasmodium falciparum malaria. Here we compare antibody-dependent phagocytosis of ring-infected parasite cultures in samples from a controlled human malaria infection (CHMI) study (NCT02739763). Protected volunteers did not develop clinical symptoms, maintained parasitaemia below a predefined threshold of 500 parasites/μl and were not treated until the end of the study. Antibody-dependent phagocytosis of both ring-infected and uninfected erythrocytes from parasite cultures was strongly correlated with protection. A surface proteomic analysis revealed the presence of merozoite proteins including erythrocyte binding antigen-175 and -140 on ring-infected and uninfected erythrocytes, providing an additional antibody-mediated protective mechanism for their activity beyond invasion-inhibition. Competition phagocytosis assays support the hypothesis that merozoite antigens are the key mediators of this functional activity. Targeting ring-stage parasites may contribute to the control of parasitaemia and prevention of clinical malaria

A synthesis of past, current and future research for protection and management of papyrus (Cyperus papyrus L.) wetlands in Africa

Papyrus wetlands (dominated by the giant sedge Cyperus papyrus L.) occur throughout eastern, central and southern Africa and are important for biodiversity, for water quality and quantity regulation and for the livelihoods of millions of people. To draw attention to the importance of papyrus wetlands, a special session entitled ‘‘The ecology of livelihoods in papyrus wetlands’’ was organized at the 9th INTECOL Wetlands Conference in Orlando, Florida in June 2012. Papers from the session, combined with additional contributions, were collected in a special issue of Wetlands Ecology and Management. The current paper reviews ecological and hydrological characteristics of papyrus wetlands, summarizes their ecosystem services and sustainable use, provides an overview of papyrus research to date, and looks at policy development for papyrus wetlands. Based on this review, the paper provides a synthesis of research and policy priorities for papyrus wetlands and introduces the contributions in the special issue. Main conclusions are that (1) there is a need for better estimates of the area covered by papyrus wetlands. Limited evidence suggests that the loss of papyrus wetlands is rapid in some areas; (2) there is a need for a better understanding and modelling of the regulating services of papyrus wetlands to support trade-off analysis and improve economic valuation; (3) research on papyrus wetlands should include assessment of all ecosystem services (provisioning, regulating, habitat, cultural) so that trade-offs can be determined as the basis for sustainable management strategies (‘wise use’); (4) more research on the governance, institutional and socio-economic aspects of papyrus wetlands is needed to assist African governments in dealing with the challenges of conserving wetlands in the face of growing food security needs and climate change. The papers in the special issue address a number of these issues

Fingerponds: seasonal integrated aquaculture in East African freshwater wetlands : exploring their potential for wise use strategies

This study was stimulated by the need for an integrated approach in wetland wise use. Sustainable management is critical for long-term ecosystem health and people's livelihoods. The potential for smallholder integrated agriculture-aquaculture as one of the possible wetland wise use strategies was explored in two sites on the northern Kenyan shores of Lake Victoria: Kusa and Nyangera.Most riparian communities living along the shores of Lake Victoria rely on wetland farming or harvesting of natural wetland products for their livelihoods. The potential for the enhanced benefits from these ecosystems through smallholder agriculture-aquaculture wetlands systems integrated into existing farming activities was investigated. Ponds were dug in the wetlands and were used for fish production whilst excavated soil was used to create raised bed gardens for vegetable production. These integrated fish/crop production systems are called 'Fingerponds', Annual floods stocked the ponds naturally. After flood recession, manure from the adjacent village was used to improve pond productivity. Locally demanded vegetables were grown in the gardens.The predominantly clayey soils around Lake Victoria are generally suitable for aquaculture. The pilot study revealed that earthen ponds dug in the wetland (Fingerponds) can be adequately stocked during annual floods with local fish species (>3 fish/m2). The dominant migrant fish into the ponds consisted of three species of tilapia (Oreochromis niloticus, O. variabilis and O. Ieucostictus), Clarias gariepimts and Protopterus aethiopicus. Manure for pond fertilization is adequately available from the local villages. Fingerponds have the potential of enhancing the existing wetland benefits through fish and vegetable production.Soil analysis indicated that the soil textural class was clay in both sites and was generally suitable for pond aquaculture. Soil electrical conductivity and sodium levels were significantly higher in Kusa compared to Nyangera. The presence of patches of soils with encrustations of sodium salts at the wetland margin in Kusa affected the overall functioning of these systems and emphasizes the need for careful site selection. In Fingerponds, the water supply is un-regulated and the water balance is maintained by natural losses and gains. At the beginning of the season. flood events are critically important for the initial water supply. During the functional period of the ponds (which lasted for about 6 months after flood recession), precipitation accounted for nearly 90% of the total water gains whilst seepage and evaporation contributed to an average of 30 to 70% of the losses, respectively. Seasonal pond water budgets indicated that the losses outweighed the gains leading to a progressive decline of water depth during the dry season. A prediction of the effect of pond volume and weather conditions on the functional period was carried out using a dynamic simulation model. The results indicated that the culture period can be extended by 2 1/2 months by deepening the ponds to an average depth of 1.5 m. Drier weather may accelerate losses and shorten the culture period by 1-2 months.The effects of livestock manure applications on nutrient dynamics, water quality and fish yields were studied. There was no observable adverse effect of manuring on pond water quality. Regression analysis indicated that site, pond management (manuring) and the environmental and climatic variables explained a large part of the variation in NH4-N, NO3-N and total nitrogen concentrations with adjusted r2 of 0.64, 0.70 and 0.65, respectively. The explained variance for o-PO4 and total phosphorus was 58% and 61%, respectively. Manuring increased the total phosphorus concentration in the sediment but only had had marginal effects on total nitrogen. The chlorophyll a concentration was higher in manured ponds, reaching an average of 150 ?g ?1 compared to an average of 27 ?g ?1 in un-manured ponds. The net fish yields were highly variable between sites and seasons and ranged from 402 to 1068 kg ha'1, the data showing that manuring was advantageous. The duration of the culture period, site variability and manuring explained 82% of the variation in fish yields. Careful fertilization of the ponds with livestock manure can be used to improve fish yields in Fingerpond systems.The rural farming systems around Lake Victoria are predominantly subsistence with integrated crop and livestock production. The overall objective of introducing Fingerponds was to increase fish protein supply to the households and diversfy farming activities. The rural farming system was characterized using natural transect mapping alongside identification of bioresource flows between the system components. Nutrient flows were analyzed using Ecopath with Ecosim 5.1 software using nitrogen as the model currency. The model result scenario with and without the wetland demonstrated the importance of the natural wetland in the overall agroecosystem nutrient flows. The farming system is characterized by low nutrient throughput associated with low productivity. Nutrient balance at the Fingerponds sub-system level was highly positive compared to maize production, which is the dominant activity in the terrestrial ecosystem. Diversification of the farming system through integration of Fingerponds increases the nutrient flow pathways and functional diversity. However, Fingerponds had minimal impact on the agroecosystem performance indicators such as biomass to throughput (B/E) and production to biomass (P/B) ratios, which are usually used to gauge ecosystem maturity and hence sustainability potential. This is probably because the overall farming systems productivity is low and Fingerponds is a small component of a larger agroecosystem. Nevertheless, modelling such systems with Ecopath provided a better insight to the agroecosystem nutrient flows.The contribution of Fingerponds rural household livelihoods was evaluated. The strength of this innovative technology in household of livelihood outcomes lies in enhancement of natural, human and social capital. Since the production level is intermediate, the benefits may not be high in the short-term perspective. Economic analysis showed that the gross margin and net income of Fingerponds is about 752 Euros and 197 Euros per hectare per year, respectively. This is about 11 % increase in the annual gross margin of an average rural household around Lake Victoria. The additional per capita fish supply is 3 kg per season or more from a 192 m2pond. The potential fish protein supply of 200 kg/ha is high compared to most existing terrestrial protein production systems. Fingerponds have potential contribution to household food security and livelihood. The results of the sensitivity analysis indicated that the biophysical variations, which may occur from one wetland to another, have implications on the functioning and consequently the economic performance of these systems. This reinforces the need for the integration of these systems into other household activities to protect the household from the potential risk.Fingerponds technology is promising, especially for rural riparian households living around seasonally flooded wetlands in Africa. There are however, challenges to this technology ranging from uncertainty of some of the key drivers of the functioning of this system (e.g. water and seed fish supply) due to reliance on natural processes to policy issues. The initial investment required for Fingerponds construction may limit some poor households. There is need for support from governments and non-governmental organizations(NGOs). There is also need for a clear policy on wetland land tenure systems and land use to create more responsibility and wise use. Finally, there is also need for research on scaling up of Fingerponds

<span style="font-size:12.0pt;line-height:115%; font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-IN;mso-fareast-language:EN-IN;mso-bidi-language:HI">Viscometric studies for some 1:1 electrolytes in water + <i>tert-</i>butyl<i> </i>alcohol and water + <i>tert-</i>butylamine<i> </i>mixtures at 298.15 K</span>

1139-1145<span style="font-size:12.0pt;line-height:115%; font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:hi"="">Viscosity and density measurements for NaI, KI , BU4NI, LiCl and KCl in various mixtures of water with tert-butyl alcohol and tert-butylamine have been carried out at 298.15 K. The viscosity data have been analysed on the basis of the Jones-Dole equation and viscosity B-coefficients have been evaluated. The small and positive values of B coefficients for LiCl in mixed liquid solvents as observed in both systems lead to the conclusion that ion-solvent interaction is not strong. The B coefficients for hydrophobic Bu4NI are large, positive and fairly constant for both systems probably due to the absence of specific hydration and solvation effects. The values of B coefficient for KCl exhibit a minimum in the water-rich region for both systems. However, the solvent composition dependence of B coefficients for both NaI and KI electrolytes are drastically different in the two solvent systems. The viscosity B coefficients for NaI and KI are significantly reduced in tert-butylamine-rich mixtures while in tert-butyl alcohol-rich mixtures they increase profoundly compared to water-rich mixtures. Values of the partial molar volumes of the electrolytes at infinite dilution in the various solvent mixtures have been evaluated from the density measurements.</span