Soil acidity is influenced by high levels of aluminium, iron, manganese and low levels of Cation Exchange Capacity (CEC), plant nutrients availability such as phosphorus, affect the growth of symbiotic-fixing bacteria in soybean which is detrimental to nodule formation and functioning. In an attempt to evaluate liming effects on soil pH, nitrogen fixation and seed protein content, an experiment was set up using a randomized complete block design (RCBD) layout in a split-plot with four replications at the Crop Museum, the Sokoine University of Agriculture in Morogoro, Tanzania. Soybean genotypes (Bossier, Laela and Uyole soya-1) were used as the main plot, while lime levels (1560, 936 and 624 kg/ha) were used as the subplot. The analysis of variance (ANOVA) showed a significant influence of lime levels on soil pH, quantities of nitrogen fixed and seed protein content. There was a significant difference (P = 0.001) observed among soybean genotypes with the application of 1560 kg/ha of lime (pH 6.5), recording the highest (7.6) nodule counts and nodule dry weight (19.26). Among the different varieties used in the study, Bossier was observed to have a fixed 24.46 kgN/ha, while Laela produced the highest (10.60%) seed protein content. Application of 1560 kg/lime observed a significant increase in kgN/ha (35.71) as well as a minimal increase (15.66%) in seed protein content at pH 6.5. Interaction effects (P = 0.05), however, observed Laela has fixed the highest nodule (7.6) counts, nitrogen fixation (44.90 kgN/ha), with Bossier recording the highest (20.22%) seed protein. The study revealed that the physiochemical properties of acid soil, as well as soybean yield components such as nodules, N2 fixation and seed protein content, can be maximally improved when limed with CaCo3

Ferralsols are the predominant soil type covering about 70% of the total land area of Uganda; they are mostly found in the Central and Western regions of the country. Ferralsols are highly weathered, acidic and have inherently low nutrient reserves. Degradation of these soils has led to reduced agricultural production and productivity. Despite the increased human population and the importance of Agriculture to the majority of the households in Uganda, little or no research has been carried out on Acid Ferralsols to improve food security and sustain livelihoods. Besides, the country’s research programs have not prioritized the use and management of soil fertility management strategies such as liming. Crop yields on these soils are often far less than those on research stations. This review paper focuses on the extent and effects, causes, challenges and opportunities associated with liming Acid Ferralsols and the effects on soil properties and crop yield. Many studies have shown that detrimental effects of acid soils can be ameliorated through liming, thus improving on the physio-chemical properties to improve crop production and yield. More research is anticipated to develop lime requirements for acid Ferralsols so as to meet the growing food demand in Uganda.

Soil acidity limits crop productivity and affects food security, household income as well as the environment. Given the consequences of soil acidity, appropriate measures such as sustainable use of agricultural lime could be an option to enhance the productive capacity of acid soils. The study was conducted to assess the growth, yield, and yield components of soybean response to liming in acid soil. The experiment was laid out in a split-plot with four replications at the Crop Museum, Sokoine University of Agriculture, Morogoro, Tanzania. Three soybean varieties (Bossier, Laela, and Uyole soya-1) were used as the main plot, and four levels of lime (L0:0, L1:1560; L2:936, and L3:624 kg/ha) were used in the subplot. The analysis of variance revealed that the variety Uyole soya-1 had the highest average number of filled pods per plant, number of pods per plant, number of seeds per pod, and 100 seed weight. The variety Laela had the highest grain yield (kg/ha) of all the varieties used in the study. The results also showed that the application of 1560 kg/ha of lime in acid soil raised the soil pH from 5.0 to 6.5 thus having a significant influence on growth, yield and yield components.

A study to examine the linkages between soil acidity, soil plant nutrients and land use on Ferralsols was carried out on smallholder farms in Central Uganda. The objective of the study was to assess the effect of soil pH on soil plant nutrient availability under the current land use. The study was carried out in Mpigi, Masaka, Wakiso, Mukono and Mubende districts representing Central Uganda. Soil samples were randomly collected from Coffee, Banana, soybean, common bean, maize and virgin fields in the five districts and the pH and plant nutrient analyzed accordingly. The analysis of variance (ANOVA) showed significant difference (p<0.01) on soil nitrogen, Calcium (p< 0.05) and Magnesium (p< 0.05). When treatment was assessed, the study showed significant difference (p< 0.01) on potassium. Besides, the study also showed high concentrations of Manganese (Mn) and Iron (Fe) in addition to very high sand and low silt and clay contents. The current land use for coffee production in Masaka district recorded the lowest soil pH (4.4) followed by annual fields (pH 4.60) in Mpigi. The highest soil pH (5.7) was recorded in banana fields in Mubende. The study also recorded very low to low N, P and K. Generally, the study observed rapid soil fertility decline in smallholder farms in the region.