Effects of Different Composting Methods and Application Rates on Growth and Yield of Carrot (Daucus carota L.)

Abstract

Aims: The aim of this study was to evaluate the effects of different composting methods (bucket, heap, and pit) and application rates (5, 10, and 15 t/ha), as well as un-composted poultry manure, on the growth, yield, and nutritional quality of carrot across two agro-ecological locations in the Ashanti Region of Ghana. Study Design: A Randomized Complete Block Design (RCBD) with three replications was used. Place and Duration of Study: The study was conducted at Adanwomase Senior High School Research Farm in the Kwabre East District and the AAMUSTED Research Field at Asante Mampong Campus from January to August 2022. Methodology: The experiment included 13 treatments: three composting methods (bucket, heap, pit), un-composted poultry manure, and a control, each applied at 5, 10, and 15 t/ha. Compost was prepared according to each method, while poultry manure was applied raw. Treatments were incorporated into the soil before sowing carrot seeds. Data collected covered soil nutrients, microbial counts, vegetative growth, yield components, and root nutritional composition. Data were analyzed using ANOVA, with means separated using LSD for microbial and nutritional analyses, and Tukey’s HSD for growth and yield traits at 5% significance. It integrates soil, plant, and microbial indicators to assess the sustainability and effectiveness of organic soil management practices compared with raw manure and no-input control. Results: Application of compost and poultry manure significantly enhanced soil fertility, carrot growth, and root yield. Heap compost supplied the highest levels of major nutrients (N, P, K), while bucket compost provided higher micronutrients (Fe, Cu) and exhibited the greatest microbial activity. The plant height increased with higher application rates, particularly at 15 t/ha. The highest root yields were recorded with 15 t/ha bucket compost, followed by poultry manure and heap compost, with the control producing the lowest yield. Carrot roots from amended plots also had improved nutritional quality, notably in ash, carbohydrate, calcium, fibre, and iron contents. Conclusion: The bucket compost at 15 t/ha produced the highest yields, while the heap compost provided the greatest major nutrient levels.