Effects of Agricultural Lime Types on Soilproperties and Maize (Zea Mays L) Performance in Soils of Tharaka Nithi County, Kenya
Kirui, Kibet Peter
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Soil acidity is a widespread problem affecting 40% of total arable land globally and about 13% of Kenyan total land area. Acidic soils are generally infertile with limited plant growth due to buildup of Al3+, H+,Fe2+, and Mn2+ toxicities and deficiencies of K+, P, Ca2+, Mg2+. P deficiency reduces maize grain yield by 28% while Al3+toxicity reduces by about 16%. Liming is a solution to ameliorate acidic soils, but its use islimited by farmers’ lack of awareness on its use and inadequate information on various lime sources quality and effectiveness in ameliorating soil acidity.The mainobjective of this study was to determine the effect of amending acid soils of Tharaka Nithi County with three agricultural lime types to improve soil productivity and maize yields. The specific objectives of the study were;To evaluate the effects of granular lime-Phosphate interaction on shoot P concentration and maize performance under glasshouse conditions, to determine the effect of amending acid soils with lime types (calcium oxide, calcium carbonate and Calcium oxide.magnesium oxide lime) on selected soil chemical properties in Tharaka Nithi County andto determine effects of agricultural lime types on maize growth and yields. There were two experiments in this study; a glasshouse and a field experiment. Theglasshouse experiment was set up in a completely randomized design (CRD) withfour replications at Kenyatta University. The treatments comprisedof granulated CaO.MgO lime at four levels (0, 2, 4, 6 t ha-1) and P-fertilizer at four levels (0, 30, 60, 90 kg P ha-1). The field experiment was set up on station following a randomized complete block design (RCBD) in four replications. The treatments comprised three lime materials (Calcium carbonate, calcium oxide and granular CaO.MgO lime) and fertilizer. Maize (Zea mays) variety H516 was used as the test crop. Key variables measured were soil chemical properties; available P, pH, Ex. acidity, plant growth parameters; height, chlorophyll content, and grain yield. All data were subjected to analysis of variance (ANOVA) using SAS 9.2 software. In the glasshouse experiment, results showedthat sole 6t/ha lime recorded the highest pH increase of 44.4% compared to control. The highest soil exchangeable P (41.3ppm), leaf %P concentration (0.55%) and above ground biomass at 4WAP (6.25g/plant) was recorded in the rate of 6t/ha lime+90kgP/ha. 6t/ha lime+60kgP/ha treatment recorded the highest plant height (142.62cm).At 8WAP,4t/ha lime+90kgP/ha treatment recorded highest above ground biomass (34.87g/plant). Results from the field experiment showed thatplots receiving lime recorded an increase in soil pH. CaCO3 treatment recorded the highest pH increase in LR16 (0.45), SR16 (0.8) in Kirege and similarly in Kangutu during LR16 (+0.39) SR16 (+0.71) seasons. Application of lime types significantly decreased soil exchangeable acidity. CaCO3 treatment recorded the highest decrease across both seasons and sites with-0.07(C mol kg-1) (LR) and -0.26 (C mol kg-1)(SR16) in Kirege and decreases of -0.125(C mol kg-1) (LR16) and -0.13(C mol kg-1) (SR16) in Kangutu from the baseline values. Application of all lime types and sole fertilizer significantly increased soil available P in both seasons and sites. CaCO3+Fertilizer treatment recorded significantly highest change +26.12ppm and +40.25 ppmin LR16 and SR16 respectively at Kirege site and +14.37ppm (LR16) and +18.75ppm (SR16) at Kangutu. Application of granular lime with P fertilizer had the lowest effects on soil available phosphorous in comparison to CaO+fertilizer and CaCO3+fertilizer treatments in both seasons in Kangutu.CaCO3 + fert recorded the highest maize grain yield of 2.55 tha-1,and 1.22 tha-1 during LR and SR,respectively in Kangutu and 3.1 tha-1 in Kirege. Results from this study showed that combination of CaCO3 lime and fertilizers was the most consistent in ameliorating acidic soil and is recommended for use in acidic soils of Tharaka Nithi County, Kenya.