EVALUATION OF SOIL CHEMICAL PROPERTIES AND CARROT PERFORMANCE AS INFLUENCED BY INTEGRATED APPLICATION OF POULTRY MANURE AND COCOA POD HUSK IN THE RAINFOREST AGROECOLOGICAL ZONE OF NIGERIA

The high cost of inorganic fertilizer, difficulties involved in its use, its scarcity, coupled with its adverse effects associated with its continuous use on soil quality prompted the need to research into cheap, locally available organic materials to combat soil fertility problems. Field experiments were conducted in 2019 and 2020 to evaluate the effects of the integrated application of poultry manure (PM) and cocoa pod husk (CPH) on soil chemical properties, growth, leaf nutrients content and yield of carrot at Igba in the rainforest ecology of southwest Nigeria. The treatments consisted of PM and CPH each at three levels (0, 5, 10 t ha-1) in a 2 x 3 factorial experiment laid into randomized complete block design with three replicates. Data were collected on soil chemical properties, growth parameters, leaf nutrients content and yield parameters. Data collected were subjected to analysis of variance using Statistical Analysis System Institute Package (SAS, 2000). The soil was slightly acidic (pH 5.5.), low in nitrogen (0.12g kg), available phosphorus (8 mg kg-1). Integrated application of PM and CPH significantly (P< 0.05) improved soil pH, organic carbon, total N, available P, exchangeable bases and lowered exchangeable acidity. Plots with integrated application of PM and CPH had higher values of soil pH, exchangeable bases, ECEC, total N, total organic carbon, available P and lower values of exchangeable acidity and micronutrients than the plots with their sole applications. There were reductions in soil pH, exchangeable bases, ECEC, total N and organic carbon in the control plots in the second cropping seasons. Growth parameters were better enhanced in plots with the integrated application of PM and CPH than either of their sole. There were significant improvements in plant height, leaf length and shoot diameter in the second cropping season in plots amended with PM, CPH and their integrations as against control plots where reductions in the growth characteristics were obtained. The leaf content of N, P, K and Ca were significantly (P< 0.05) enhanced in plots with integrated application of PM and CPH than the plots with their sole application. Carrot root yield characteristics were significantly (P < 0.05) enhanced in plots with the integrated application of PM and CPH than plots with the sole application of PM or CPH. Root yield was increased in the second cropping season in plots treated with the sole application of PM, CPH and their integrations, while there were reductions in root yield parameters in the control plots. Improvements in soil nutrients status, growth, leaf nutrients content and root yield of carrot in both cropping season in the amended plots when compared to the control plots, imply that integrated use of PM and CPH could be used in the enhancement of production of carrot on sustainable basis in the study area.