INCREASING YIELDS OF MAIZE (Zea mays L.) AND GROUNDNUT (Arachis hypogea L.): THE ROLE OF SOME SECONDARY, MICRONUTRIENTS AND CROPPING SYSTEMS

Abstract

Due to the fact that maize and groundnut yields in Northern Ghana and Ghana as a whole are significantly below potential levels, closing yield gap is viewed as a critical part of ensuring a sustainable and reliable food supply to fulfil the anticipated demand. A comprehensive study was conducted to investigate various aspects of maize production in northern Ghana. The study comprised one socio-economic and agronomic survey and three field experiments. Two, maize nutrient omission on the magnitude and spatial-temporal patterns of maize yield responses to balanced and imbalanced nutrient applications. Three, contribution of secondary and micronutrients (S, Zn and B) fertilization in enhancing yield and yield quality of maize and four, effects on yields of maize groundnut cropping systems based on co-fertilization. These survey and experiments were conducted during 2020, 2021 and 2022 at 4R-NS project sites at Eastern corridor of northern Ghana, the research farms of the CSIR-SARI experimental sites at both Nyankpala and Damongo. In experiment one, the exploitable maize yield gap at farm-level reaches up to 7 t ha-1 and less than one percent of the farmer fields could achieve maize grain yield of 4 t ha-1. The results have shown a mean yield of maize less than 1.5 tons ha-1 from all the four districts with a wide variation at a farmer level, ranged between 0.25 tons ha-1 and 4.0 tons ha-1 which proved the possibilities for yield improvement. In experiment 2, nutrient omission trials were conducted on 24 farms located in East Gonja, Kpandai, Nanumba North and Nanumba South selected to be representative of the main soil and management factors in maize based systems of Northern Ghana. Treatments comprised PK, NK, NP, NPK, and NPK plus SMN administrations in addition to a control (no fertilizer). The responses of maize yield to NPK plus SMN treatments showed clear spatial-temporal patterns. The first cropping season showed mean maize yields of 0.9, 1.2, 1.9, 3, 2.9, and 3.6 t ha−1, whereas the second cropping season gave mean yields of 0.4, 0.8, 1.2, 31.9, 2.5, and 3.1 t ha−1 across the control, PK, NK, NP, NPK, and NPK + SMN treatments. The third season gave values of 0.5, 0.6, 0.8, 1.2, 1.6, and 1.9 t ha−1 in contrast. In experiment 3, the field was laid in a split plot design with three replications. The main plot factor treatments were two NPK rates: 60, 40, 40 kg ha -1 and 90, 60, 60 kg ha -1 and the sub plot factor treatments were ten combinations of secondary and micronutrients (sulphur, and zinc and boron) and control (no MN). In Nyankpala, yields of 4.5 and 5.0 tons ha-1 were achieved with inclusion of S, Zn and B in both years while in Damongo, yields of 3.26 and 2.58 t ha-1 were achieved. For NPK-only treatment, average yields of 2.30 and 2.53 were achieved in Nyankpala for both years while 1.28 and 1.48 were achieved in Damongo. In experiment four, five cropping systems (viz. sole continuous maize (SCM), sole continuous groundnut (SCG), maize-groundnut intercrop (MGI), groundnut/maize rotation (GMR) and maize/groundnut rotation (MGR)), each with or without fertilizer were established under RCBD at Nyankpala during the 2021 and 2022 cropping seasons. The results showed that intercrop and rotation treatments gave significant yields. The land equivalent ratios (LER) for the intercrops were 1.2 and 1.09 respectively, in the two seasons. To optimize soil health and crop productivity, farmers should adopt integrated soil fertility management practices, including: Application of NPK fertilizer supplemented with essential micronutrients like sulfur (S), zinc (Zn), and boron (B). Implementation of intercropping and rotation systems featuring maize and groundnut.These practices will enhance resource use efficiency, mitigate soil degradation, improve soil fertility, and ultimately boost overall productivity.