| dc.description.abstract | Agriculture is the main source of livelihood in Kenya with maize being produced in
diverse environments. However, in Meru and Tharaka Nithi counties, small holder
maize productivity has been diminishing due to declining soil fertility and frequent
droughts. Nitrogen (N) is the principal nutrient limiting maize production hence the
need for intercropping using cowpeas that are inoculated with the correct exotic
bacterial strain that fix N in the soil. There was need to assess N fixation capacity
using exotic bacteria by inoculating cowpeas with the correct bacterial strain. The use
of N fixing legumes in intercrops with cereal crops remains a cheaper and viable
option available for the resource constrained farmers to enhance soil fertility. The
objective of the study was to contribute towards improved maize performance
through rhizobium inoculated cowpeas intercropping. The study was conducted at
two locations i.e. Kenya Agricultural Livestock Research Organization (KALRO)
Igoji substation and Magutuni secondary school in Meru and Tharaka Nithi counties
respectively, during the long rains of the year 2018. The experiment was laid out in a
Randomized Complete Block Design and replicated three times. The treatments
included maize hybrid Duma 43 variety sown as a sole crop (TI); Rhizobium
inoculated variety K80, cowpeas maize intercrop (T2), cowpeas maize intercrop
without inoculation (T3) and non-inoculated cowpeas K80 sole crop (T4). Data
collected on maize included plant height, stem girth, canopy cover, leaf area index,
light extinction coefficient and yield. Data collected on cowpea was yield. Moisture
retention capacity was determined by use of a neutron probe after every week by
recording the moisture from the soil in millimeters up to grain filling. Soil samples
for N analysis were taken before planting and after harvesting on each treatment plot
basis and the homogenous sample analyzed at University of Nairobi (UoN) soil
chemistry laboratory. A general linear model was performed and data subjected to
analysis of variance (ANOVA) using GENSTAT statistical package (VSN
International, 2011). Means were separated using Fischer’s protected least significant
difference (LSD) at 5% probability level. Results indicated that intercropped patterns
under inoculated cowpeas recorded a greater leaf area index of 3.75 at Igoji and 3.16
at Magutuni. Light extinction coefficient was high in intercrops than in sole stands
and ranged between 0.52 and 0.34 at Igoji and between 0.57 and 0.37 at Magutuni.
Intercropped patterns intercepted more photosynthetically active radiation (PAR)
(581.54 MJm-2) than pure stands (88.35 MJm-2). At kernel development stage,
significantly higher soil moisture content was observed under intercropping patterns
T2, (255.5±3.7mm, 253.0±1.9mm) and T3, (250.7±2.9mm, 240.5±1.3mm) than in
pure maize stand T1, (245.3±4.0mm, 230.8±2.7mm) and sole cowpeas T4,
(248.9±5.6mm, 233.7±3.7mm) in Igoji and Magutuni, respectively. Nitrogen fixed in
T2, (0.20 g/kg, 0.18 g/kg) was higher than in T3, (0.18 g/kg, and 0.17 g/kg) and T4,
(0.19 g/kg, 0.17 g/kg) at Igoji and Magutuni respectively and this was attributed to
the effect of inoculation in cowpeas. The results of this study underpins the
importance of intercropping maize with inoculated cowpeas as a cheaper soil fertility
improvement method and as a moisture retention strategy for resource poor farmers in
Meru and Tharaka Nithi counties. | en_US |
