Abstract:
On average Malawi is losing of 40 kg N ha-1 and 6.6 kg P ha-1 annually. Additionally,
nutrient use efficiency (NUE) is low as a result of declining levels of soil organic matter
(SOM) and associated deficiencies of other macro and micronutrients. This is usually
below 20 kg maize grain kg-1 of nutrients applied. To investigate on the possibility of
improving NUE a study was initiated in the 2011/12 cropping season with a parallel trial
mounted along side in the second season, both were laid in a randomized complete block
design replicated three times. The trials involved planting of pigeon pea as monocultures
or as intercrops. The main trial had eight treatments while the parallel trial had ten
treatments. After the first season legume biomass in some plots of the main trial was
buried into the soil. Soil characterization was conducted before treatment application in
the first and second year. Data were analyzed using genstat and subjected to analysis of
variance at 5% level of confidence. Means were separated using the least significant
difference. Generally, the soil chemical characteristics for soil samples collected in all the treatment plots both in the main and parallel trial indicate that the soil has low fertility. The
organic carbon (OC), cation exchange capacity CEC (NH4OAc), and total N (%) was low,
and was at 1.4 %, 3.5-3.6 cmol (+)/kg soil, 0.12%, while available phosphorus (Mehlich 3)
was marginally adequate (mean=21.5 mg kg-1 and 22.1 mg kg-1). The soil texture which
was predominantly sandy clay loam to sandy clay coupled to the low CEC suggest
potential high leacheability of nutrient elements more especially nitrogen as nitrate.
Inevitably, if the soil is not properly managed crop yield could be reduced drastically.
