Effect of Mavuno Phosphorus-Based Fertilizer and Manure Application on Maize Grain and Stover Yields in Western Kenya

Low crop productivity in western Kenya can be attributed to low soil fertility and limited use of organic and inorganic fertilizers. This is attributed to high costs of fertilizer, inconsistent application and duration of use. Efforts to improve and maintain soil productivity through use of manure and fertilizer among others has been ongoing in western Kenya for years. Despite these efforts low crop yield associated with limited use of common compound fertilizers is still prevalent. Remarkable increases in yield have been noted with compound fertilizers which offer additional benefits in terms of nutrient supply. Mavuno a locally blended fertilizer promoted in western Kenya offers such benefits. The objective of this study was to evaluate the effect of mavuno phosphorus-based fertilizer and manure on maize and stover yields in Nyalgunga, Nyabeda and Emusutwi sub-locations, western Kenya; where low soil fertility, coupled particularly with low available phosphorus  has been pointed out as the major factor limiting crop productivity.  The study was carried out on fields where mavuno fertilizer at 20kg P ha-1 and manure at 2t ha-1 has been applied for six years. A randomized block design was used and maize grain and stover yields calculated from the four treatment fields; control (no input), manure (2t ha-1), mavuno (20kg P ha-1) and manure (2t ha-1) + mavuno (20kg P ha-1). There was a remarkable increase in maize grain yield (control 904 kg ha -1, manure+ mavuno 2238 kg ha -1) a 148% increase in yield above control plot (p=<0.001) and stover yield (control 825 kg ha -1, manure+mavuno 1381 kg ha -1) a 67% increase above control plot (p=<0.001).  Mavuno phosphorus-based fertilizer and manure have a positive effect on maize grain and stover yield and can sustain soil productivity under long term use, their application in soils  improves availability of phosphorus to plants resulting in high yields and improved soil properties. Understanding the effect of continuous application of phosphorus-based fertilizers and manure is essential for sustaining soil productivity among small holder farms of western Kenya to meet the high food demand, which is currently forcing farmers to continuously grow maize on the same piece of land resulting to soil degradation. Keywords: Mavuno, manure, Maize grain yield, Maize stover and Western Keny

Presence and distribution of mosquito larvae predators and factors influencing their abundance along the Mara River, Kenya and Tanzania

Among all the malaria controlling measures, biological control of mosquito larvae may be the cheapest and easiest to implement. This study investigated baseline predation of immature mosquitoes by macroinvertebrate predators along the Mara River, determined the diversity of predators and mosquito larvae habitats and the range of their adaptive capacity to water physico-chemical parameters. Between July and August 2011, sampling sites (n=39) along the Mara River were selected and investigated for the presence of macroinvertebrate predators and mosquito larvae. The selected sampling sites were geocoded and each dipped 20 times using standard mosquito larvae dipper to sample mosquito larvae, while a D-frame dip net was used to capture the macroinvertebrate predators. Water physico-chemical parameters (dissolved oxygen, temperature, pH, conductivity, salinity and turbidity) were taken in situ at access points, while hardness and alkalinity were measured titrimetically. The influence of macroinvertebrate predator occurrence was correlated with mosquito larvae and water quality parameters using Generalized Linear Model (GLM). Predators (n=297) belonging to 3 orders of Hemiptera (54.2%), Odonata (22.9%) and Coleoptera (22.9%), and mosquito larvae (n=4001) belonging to 10 species, which included An.gambiae s.l (44.9%), Culex spp. (34.8%) and An. coustani complex (13.8%), An. maculipalpis (3.6%), An. phaorensis (1.2%), An. funestus group (0.5%), An. azaniae (0.4%), An. hamoni (0.3%), An. christyi (0.3%), An. ardensis (0.08%), An. faini (0.07%), An. sergentii (0.05%) and 0.05% of Aedes mosquito larvae which were not identified to species level, due to lack of an appropriate key, were captured from different habitats along the Mara river. It was established that invasion of habitats by the macroinvertebrate predators were partially driven by the presence of mosquito larvae (p < 0.001), and the prevailing water physico-chemical parameters (DO, temperature, and turbidity, p <0.001). Understanding abiotic and biotic factors which favour mosquitoes and macroinveterbrate co-occurrence may contribute to the control of malaria

Effects of water physico-chemical parameters on tilapia (Oreochromis niloticus) growth in earthen ponds in Teso North Sub-County, Busia County

Abstract Small-scale fish farmers in developing countries are faced with challenges owing to their limited information on aquaculture management. Nile tilapia farmers in Teso North Sub-County recorded lower yields than expected in 2009 despite having been provided with required inputs. Water quality was suspected to be the key factor responsible for the low yields. This study sought to assess the effects of earthen pond water physico-chemical parameters on the growth of Nile tilapia in six earthen fish ponds under semi-intensive culture system in Teso North Sub-County. The study was longitudinal in nature with pond water and fish being the units of analysis. Systematic sampling was used to select five ponds while a control pond was purposively selected based on its previously high harvest. Four ponds were fed by surface flow and two by underground water. Each pond was fertilized and stocked with 900 fry of averagely 1.4 g and 4.4 cm. Physico-chemical parameters were measured in-situ using a multi-parameter probe. Sixty fish samples were randomly obtained from each pond fortnightly for four months using a 10 mm mesh size and measured, weighed and returned into the pond. Mean range of physico-chemical parameters were: dissolved oxygen (DO) 4.86–10.53 mg/l, temperature 24-26 °C, pH 6.1–8.3, conductivity 35–87 μS/cm and ammonia 0.01–0.3 mg/l. Temperature (p = 0.012) and conductivity (p = 0.0001) levels varied significantly between ponds. Overall Specific Growth Rate ranged between 1.8% (0.1692 g/day) and 3.8% (1.9 g/day). Ammonia, DO and pH in the ponds were within the optimal levels for growth of tilapia, while temperature and conductivity were below optimal levels. As temperature and DO increased, growth rate of tilapia increased. However, increase in conductivity, pH and ammonia decreased fish growth rate. Temperature and DO ranging between 27 and 30 °C and 5–23 mg/l, respectively, and SGR of 3.8%/day and above are recommended for higher productivity

Effects of Land Use Types on the Levels of Microbial Contamination Based on Total Coliform and Escherischia coli counts on the Mara River, East Africa

The effects of land use types on levels of microbial contamination based on total coliforms and E. coli (faecal coliform) levels was investigated in the Mara River system, Kenya and Tanzania. Water samples were taken from five sampling sites with different land uses and the Most Probable Number (MPN) method used to determine the total coliforms. A biochemical test was done and the proportions of E. coli bacteria given per study site. The mean concentration of total coliforms was lowest at Silibwet Bridge and highest at Kirumi Bridge. However, counts of E. coli were highest at an urban site (Bomet Bridge) and lowest at a swamp site (Kirumi Bridge). Overall, the proportion (40.9%) of Eosin Methylene Blue (EMB) broth plates that produced E. coli in the study sites was higher than the WHO recommended standards of 0% per 100 ml in potable water. The results show that sections of the river with most human activity and inappropriate types of land-use contributed to high levels of coliform bacteria, particularly E. coli. This may indicate the existence of point sources of faecal contamination along the Mara River and corrective measures should be taken to control them.Keywords: E. coli, faecal coliform bacteria, land use type, most probable number, Mara River