Conclusions
This work demonstrates that continuous intercropping for 3–4 years and fertilizerP application enhanced crop productivity and nutrient acquisition compared withthe corresponding monocrops. Intercropping did not alter soil OM andmaintained soil total N under continuous overyielding and greater nutrientremoval in the relatively fertile soil studied. Soil Olsen P, exchangeable K and CECwere more depleted in intercropping than the corresponding monocrops due togreater nutrient removal in intercropping than in the monocultures in a situationwhere there were no applications of fertilizer K or farmyard manure. Soil Olsen Pincreased significantly at 40 kg fertilizer P ha21but did not increase further withadditional P to 80 kg P ha21. Therefore, the reduction in Olsen-P, exchangeable Kand CEC of soils can be alleviated by proper fertilization. In general, there was noconsistent or significant difference in soil pH between intercropping andmonocultures. In the majority of cases, soil enzyme activities in intercropping didnot differ from the monocrops, with the exception of acid phosphatase activitywhich was higher in intercropping than the corresponding monocrops. Ourinvestigation further confirms that there are advantages of intercropping in termsof yield and nutrient acquisition, with soil fertility maintained over a period of atleast 3–4 years with proper fertilization under conditions of high yields andnutrient removal. Further research is required to examine crop performance overlonger time periods and soil properties need to be studied over longer time scales.