Effects of mulch and mineral fertilizer on crop, weevil and soil quality parameters in highland banana

The decline of cooking banana production in parts of East Africa hasbeen associated with a loss of soil fertility and increased pest pressure.Previous work indicated that the use of mineral fertilizers at recommendedratesis not financially viable on plantations where pest pressure is high. Theobjectives of this study were to determine the effects of half the recommendedrates of mineral fertilizers and organic mulch on banana yield, soil and foliarnutrient status, soil water and pest damage in the central region of Uganda.Thestudy was conducted in a four-year old banana plantation infested with weevils.Treatments consisted of mineral fertilizer alone, mulch alone, a combination ofmulch with fertilizer, and a control (no mulch from outside the plot, ormineralfertilizer applied). Fruit yield was generally low (mean of 7.4 Mgha−1 yr−1) and increases above thecontrol ranged from 1.1 to 2.0 Mg ha−1 yr−1. Banana yield was significantly higher in the solemulch treatment than in the control. However, there were no significantdifferences in yield among the treatments that received external inputs. Thus,there was no demonstrable yield advantage of combining mineral fertilizer withmulch. At the end of the trial, soil K concentrations in the two treatmentsthatwere mulched, were almost twice those of the control, but this difference wasnotstatistically significant. Concentrations of Ca and Mg did not differ withtreatment. Soil available P significantly increased when mineral fertilizer andorganic mulch were combined. Treatments that received organic mulch were lowerin foliar concentrations of N and Mg, and higher in K. Soil water content wasgreater in the surface soil layer in the treatments that received mulch,presumably due to less surface run-off and evaporation, since there was nochangein surface soil porosity. The effect of organic and inorganic amendments had noimpact on weevil damage, which remained above 5% at the end of the trial. Weconclude that where weevil damage is over 5% of the cross section near thecollar, banana production may not be economically increased through use ofeither mineral fertilizer and/or organic mulch.