Effects of cropping systems and agricultural lime on soil properties and nutrient content of sugarcane on acidified soils of Kisumu County, Kenya

Abstract

Acid soils cause soil fertility problems such as Al and Mn toxicity, Ca, Mg, N deficiency and P fixation. These are constraints to high crop yields. Historically, liming is the common management practice used to neutralize soil acidity and to overcome the problems associated with soil acidification. A field experiment was conducted to investigate the effects of cropping systems, lime placement methods and lime rates on some soil chemical properties and nutrient uptake by sugarcane during the plant crop and ratoon one cycle under acidified Cambisols of Kibos, Kisumu, Kenya. A Split - split plot in randomized complete block arrangement was employed. The factors and respective levels (in parenthesis were): main plot; two cropping systems (sugarcane monoculture [MC] and intercropped sugarcane and soybeans [IC]). The sub – plots were three lime placement methods (lime broadcasted [L-BC], lime shallow banded, 0 – 15 cm [L-SB] and lime deep banded, 15 – 30 cm (L-DB] and the sub - sub plots were three lime rates (0, 1 and 2 t ha-1). Lime rate of 2 t ha-1 significantly (P ≤ 0.05) increased soil pH to 6.4 and 5.2 as determined in water and 1 N KCl, respectively compared to 1 t ha-1 and control (0 t ha-1). Increased lime rate led to decreased levels of manganese, iron, and copper hence confirms the inverse relationship between soil pH and these micronutrients. Lime deep banded (L-DB) increased soil pH and available phosphorus for soil depth 15 – 30 cm compared to lime shallow banded (L-SB) and lime broadcasted (L-BC). Intercropped sugarcane and soybeans (IC) led to increased soil acidity and soil organic carbon (SOC) than did sugarcane monoculture (MC). For nutrient content of sugarcane leaves, IC system led to increased Ca and Mn compared to MC. Lime broadcasted (L-BC) caused high nitrogen and phosphorus content of sugarcane leaves and lime shallow banded resulted in increased Ca and Zn content of sugarcane to optimum levels. In view of the findings, the lime rate of 2 t ha-1 is recommended for use to ameliorate soil acidity for acidified Cambisols of Kibos, Kisumu County, Kenya. Lime broadcasted (L-BC) is preferred to ameliorate acidity at top depth (0 – 15 cm) while lime banded both (L-SB) and L-DB) is preferred to reduce sub - soil acidity.