The excessive application of mineral fertilizers in maize cultivation leads to progressive soil contamination in the long term and increases the cost of production. An alternative to reduce over-fertilization is to perform a partial replacement with microbes that promote nutrition and growth, such as Arbuscular Mycorrhizal Fungi (AMF). A pot experiment which was followed by two field experiments was performed with and without the application of indigenous AMF in combination with five nitrogen–phosphorus–potassium (NPK) fertilization rates (100% NPK = N120P60K60; 75% NPK = N90P45K45; 50% NPK = N60P30K30; 25% NPK = N30P15K15; control = N0P0K0). The objective was to investigate whether the soil application of indigenous mycorrhizal fungi inoculum combined with NPK fertilization can provide higher maize yields and soil-available N, P, and K than chemical fertilization can alone. The greenhouse results showed that the application of AMF with a 50% NPK treatment significantly increased the plant’s growth, root colonization, leaf chlorophyll content, and N, P, and K tissue content. The results from the field conditions showed that there was a highly significant yield after the treatment with AMF + 50% NPK. The study also revealed that mycorrhizal fungi inoculation increased the available soil N and P concentrations when it was combined with a 50% NPK dose. This suggests that the inoculation of fields with AM fungi can reduce the chemical fertilizer application by half, while improving soil chemistry. The results suggested that AMF inoculation can be used in integrated soil fertility management strategies.

Finger-millet response to micro-dosing with N and P fertilizer in the Semi-Arid areas of eastern Uganda is not fully known. Consequently, we conducted a field study at Kuju in eastern Uganda in 2016 long and short rains. The study determined the effect of fertilizer micro-dosing and weeding time on finger-millet performance. The experiment was laid out in a randomized complete block design with a split plot treatment structure. Weeding time constituted the main plot (weeding at 20, 30, 45 DAS (days after sowing) and 20 + 45 DAS while fertilizer rates (16.6 kg N ha-1 + 10.6 kg P2O5 ha-1; 10.6 kg P2O5 ha-1; 16.6 kg N ha-1; 0 N + 0 N and 83 kg N ha-1 + 52 kg P2O5 ha-1) constituted the sub-plots. Results of this study revealed that finger-millet grain yield was highest (2182 kg ha-1) at fertilizer micro-dosing (16.6 kg N ha-1 + 10.6 kg P2O5 ha-1) and lowest (950 kg ha-1) in plots with no fertilizer. Fertilizer micro-dose application (16.6 kg N ha-1 + 10.6 kg P2O5 ha-1) caused early flowering of finger-millet (52.2 days), whereas delayed flowering was recorded, where 16.6 kg N ha-1 (55.12 days) was applied. The interaction between time of weeding and fertilizer rates significantly (P < 0.05) increased finger millet growth and grain yield. The interaction of N and P fertilizer micro-dose with weeding once at 20 DAS had the highest finger-millet grain yield. Therefore, it is recommended that fertilizer micro-dosing can be used to enhance finger-millet productivity.

Finger millet yields in farmers’ fields are low primarily due to low soil fertility and poor weed management. Fertilizer application could be one of the key strategies used to address the problem. However, due to high cost of fertilizer, its utilization has been limited to very few farmers in the country. Consequently, a study was conducted in Kuju sub-county, Amuria district in Eastern Uganda during 2016 long and short rains to determine the effect of micro dosing and weeding time on finger millet performance and weed growth. The experiment was laid out in a randomized complete block design in a split plot treatment structure. Weeding times constituted the main plot [weeding at 20 DAS (days after sowing), 30 DAS, 45 DAS, and 20 & 45 DAS (double weeding)], while fertilizer rates (N 16.6 kg ha-1 + P2O5 10.6 kg ha-1; P2O5 10.6 kg ha-1; N 16.6 kg ha-1; N0 + P0, and N 83 kg ha-1 + P2O5 52 kg ha-1) constituted the sub plots. Results of this study revealed that the interaction between weeding at 45 DAS and fertilizer micro-dosing significantly (P < 0.05) reduced weed biomass (7.7 × 10-4 kg ha-1) without significant increase in finger-millet grain yield. Interaction of fertilizer micro-dosing (N 16.6 kg ha-1 + P2O5 10.6 kg ha-1) with weeding once at 20 DAS recorded the highest (2292 kg ha-1) finger millet grain yield with significant (P < 0.05) reduction in days to finger millet flowering. Therefore, it is recommended that fertilizer micro-dosing at N 16.6 kg ha-1 + P2O5 10.6 kg ha-1 and weeding once at 20 DAS can be used to control weeds and enhance finger-millet productivity.

Despite the recommendation for fertilizer use in crop production by research, there is a low rate of adoption among farmers. The low adoption rate of fertilizer usage has been partly attributed to high costs of fertilizer in addition to use of agronomic recommendation without fertilizer economic analysis. The study therefore, set out to determine the profitability of fertilizer micro dosing and weeding regimes in finger millet production in eastern Uganda. A randomized complete block design in split plot treatment arrangement with three replications was used. Weeding regime treatments were the main plot and fertilizer micro dosing treatments as the sub plots. The treatments included: different micro dosing rates of nitrogen and phosphorus, weeding regimes and SEREMI II finger millet variety. Nitrogen was applied in the form of urea (46%), in two splits of 50% each at vegetative and flowering stages respectively. The results of the study indicate that weeding once at 20 Days After Sowing (DAS) and a combination of N and P (16.6 kg N ha -1 and 10.6 kg P ha -1 ) fertilizer micro dose application is the most profitable combination and could make farmers earn up to Uganda shillings 1,984.220 per hectare compared to only Uganda shillings 373,000 from none application of fertilizer. We therefore conclude that finger millet producers can achieve higher economic and environmental gains when weeding is done once at 20 DAS in combination with sole P fertilizer micro dosing applied at 10.6 kg P ha -1 .