Influence of simulated acid soil ph (4.0) on proximate and elemental composition of phaseolus lunatus (linn.) (lima bean), amended with agricultural lime and organic manure

Abstract

This study examines the impact of acidic soil conditions, specifically at pH 4.0, on the proximate and elemental composition of Phaseolus lunatus (Lima bean) and the effectiveness of agricultural lime and organic manure as soil amendments. The experiment was laid in a 1×1×4 factorial and data for all parameters were analyzed using analysis of variance. Growth on the simulated acid soil was achieved by irrigating soil with acidified water, simulated by mixing sulphuric and nitric acids in a 2:1 ratio. The simulated acid soil was subsequently treated with agricultural lime and organic manure prior to planting, with 50 g of each amendment mixed with 5 kg of each soil. Proximate such as moisture content, protein, fat, fiber, and ash, while macro and micronutrient contents in the harvested beans were carried out. Results of physico-chemical properties revealed that acidic soils amended with a combined treatment of agricultural lime and organic manure improved the soil pH towards neutrality (from 4.0 to 7.65).  Mineral nutrients analysis revealed a significant (P<0.05) improvement in content for P. lunatus grown on soils amended with organic manure and a combination of agricultural lime and organic manure. The mineral composition was comparable, calcium was significantly (P<0.05) higher in Lima beans grown on unamended acidic soils (pH 4.0) with values ranging from 2022.3% to 5962.3% compared to amended soils values of 1326.3 % to 1381.3%. The application of agricultural lime effectively raised soil pH and improved the nutrient composition of the beans, while organic manure enhanced nutrient availability and improved overall plant health. The combined application of both amendments resulted in the highest nutritional values, indicating a synergistic effect in ameliorating the negative impacts of soil acidity. P. lunatus had higher carbohydrates and moisture content (p<0.05) under the different amended soils. The results of the elemental composition revealed that P. lunatus is rich in macro and micro nutrients. This study has shown the importance of appropriate soil management strategies for enhancing the nutritional quality of Phaseolus lunatus in acid induced soil. The study also revealed that these amendments not only enhanced the nutrients composition of Phaseolus lunatus but also positively impacted the soil physico-chemical properties and nutrients availability.