Fertilizer Microdosing in the Humid Forest Zone of Ghana: An Efficient Strategy for Increasing Maize Yield and Income in Smallholder Farming

Abstract

Core Ideas N–P–K fertilizer microdosing increased maize yields by 99% in the humid forest zone. Gleyic Plinthic Acrisol produced higher maize grain yield than the Plinthic Acrisol. Microdosing increased N, P, and K use efficiency of maize in rotation vs. sole cropping. Maize grain yield and net returns were optimal with N20P40K20 and N0P40K20 microdoses. High fertilizer costs pose a challenge in smallholder farming; optimizing fertilizer recommendations that are affordable to resource‐poor farmers could increase crop yield and income. The study aimed to determining the yield and economic effects of N–P–K fertilizer microdosing on maize (Zea mays L.) crops on Gleyic Plinthic Acrisol (GPA) and Plinthic Acrisol (PA) in the semideciduous rainforest zone of Ghana using a split‐plot randomized complete block design with three replications. The field trial included two cropping systems (continuous maize cropping [CMC] and cowpea [Vigna unguiculata (L.) Walp.]–maize rotation [CMR]) as main plots with four treatments (N0P0K0, N0P20K20, N0P40K20, and N20P40K20) and the recommended fertilizer rate (N90P60K60) as subplots. Fertilizer treatment effects on maize stover and grain yields were assessed. The microdose treatments increased maize yields by 32 to 99% across cropping systems and soil types. Maize grain yield increase was higher on the GPA than on the PA. The N90P60K60 and N20P40K20 treatments resulted in higher grain and stover yields than the other treatments across cropping systems and soil types. Among the treatments maximum grain yield increases of 76 and 99% were obtained with N20P40K20 on the PA and the GPA, respectively, under CMC. Under CMR, grain yield increased by 46% with N0P40K20 (PA) and 74% with N0P20K20 (GPA). The largest net return was obtained with N20P40K20 under CMC across both soil types and with N0P20K20 (GPA) and N0P40K20 (PA) under CMR. These fertilizer microdoses can be considered appropriate for increasing maize yield and the income of smallholder farmers.