Abstract:
Maize (Zea mays L.) is the third most important cereal crop after wheat and rice in the
world. Maize/legume intercropping system has become one of the solutions for food
security among small scale maize producers due to unaffordability of chemical
nitrogenous fertilizers and limited access to arable land. A study was conducted to
determine the effect of maize/dry bean and maize/lablab intercropping on maize grain
yield and soil fertility status. A field experiment was conducted during 2010/2011 and
2011/2012 growing seasons at the University of Limpopo experimental farm.
Treatments included sole maize (ZM 521, an improved open pollinated variety, ex-
CIMMYT), sole lablab (Rongai, indeterminate cultivar), sole dry bean (DBS 360,
indeterminate Type II cultivar), maize/dry bean and maize/lablab intercrops arranged
in randomized complete block design with five replications. Phosphorus (P) was
applied on sole and intercropped maize at the rate of 30 kg P/ha in the form of
superphosphate (10.5%P) at planting and 40 kg N/ha of nitrogen (N) was applied in
the form of Limestone Ammonium Nitrate (LAN) (28%N) on both sole and intercropped
maize four weeks after plant emergence. For maize and dry bean, grain yield, yield
components and biomass were determined. Only biomass yield was measured for
lablab. Soil samples were collected for soil analysis at the beginning and the end of
the experiment The results showed that maize/lablab intercropping yielded
significantly (P<0.05) lowered maize grain (1259.3 kg/ha) than sole maize and
maize/dry bean intercropping which yielded maize grain of 2093.7 kg/ha and 2156.3
kg/ha, respectively. Sole dry bean yielded significantly (P <0.05) higher dry bean grain
(1778.5 kg/ha) than intercropped dry bean (691.8 kg/ha). Rongai was only flowering
by the time maize and dry bean matured hence only maize yield is reported for the
Maize/lablab intercrop. Maize/dry bean intercropping was advantageous to sole
cropping with a Land Equivalent Ratio (LER) of 1.42. The partial Land Equivalent
Ratio (PLER) for maize in maize/lablab intercropping was 0.60. Dry bean was
outcompeted by maize as calculated aggressivity value was positive at +0.64.The
highest monetary value was achieved in sole dry bean and the lowest monetary value
was found in intercrop dry bean. Soil TN, P, K, Ca, Mg and Na were reduced by both
sole cropping and intercropping systems. Intercropping with lablab is likely to
significantly lower maize yield under dryland conditions.
Key words: dry bean, grain yield, Intercropping, lablab, maize, smallholder, soil fertility.
