Abstract
A field trial aimed at assessing the performance of maize and beans under intercropped systems was conducted in 2013 under three experimental components of maize, beans and maize-bean intercrop in a randomized complete block design (RCBD) with three replications. Each component was subjected to treatments that included: a control-without fertilizer (WF), mineral fertilizer (MF) at 150 kg/ha of 17:17:17, Tithonia biomass (TDB) at 8 tons/ha and integrated application of MF and TDB comprising 4 tons/ha Tithonia and 100 kg/ha mineral fertilizer (MF/TDB). The MF/TDB produced 21.7% higher green maize yields than control, while MF and TDB produced 8.96 and 7.52% higher yields, respectively than the control. The land equivalent ratios (LER) were higher than one in all the intercropping plots, thus indicating an optimum exploitation of the environmental resources. Control plots showed the highest yield advantage in terms of LER of 1.70. When maize yield was converted to bean equivalent yield (BEY), the intercropping BEY was higher than the BEY in the sole for all fertilizer types, thereby revealing an agronomic advantage. The actual yield loss (AYL) values for maize indicated a yield gain of between 11.2 and 15.05% when MF and MFTDB were used in the intercropping compared to the sole cropping. Beans recorded yield loss in all the fertilizer types except in TDB which had a yield gain of 20.45%. The economic performance of the intercropping systems, affirmed that the most advantageous fertilizer type for maize was MF/TDB with an IA of 6.566. The monetary advantage index (MAI) indicated a definite yield and economic advantage in maize-bean intercrop over their sole cropping, with integrated use of MF/TDB as nutrient sources being the most economical and advantageous fertilizer regime. Key words: Economic efficiency, land equivalent ratio (LER), green maize, beans, intercropping advantage, monetary advantage index (MAI), Tithonia diversifolia.
Highlights
Self-sufficiency in maize (Zea mays L) production is a major strategy for achieving food security in Kenya
When maize yield was converted to bean equivalent yield (BEY), the intercropping BEY was higher than the BEY in the sole for all fertilizer types, thereby revealing an agronomic advantage
The yields of beans showed a similar trend with application of Tithonia manure and mineral fertilizer (MF)
Summary
Self-sufficiency in maize (Zea mays L) production is a major strategy for achieving food security in Kenya. The strategy is adopted to avoid undue reliance on unstable and unpredictable world food markets and to generate incomes to farmers and landless laborers (Mousavi and Eskandari, 2011). Intercropping systems are more productive than sole crops grown on the same land, because they are associated with greater yield stability, greater land-use efficiency, increased competitive ability against weeds, improvement of soil fertility due to N fixation, and some favorable root exudates from leguminous species incorporated in the systems (Mousavi and Eskandari, 2011; Lithourgidis et al, 2006). While most reports on intercrops have indicated increase in maize yields, Musambasi et al (2012) reported a low maize yield when maize and cowpea (Vigna unguiculata) were intercropped and a high yield when maize and field beans (Phaseolus vulgaris L.) were intercropped
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