Fields Preparation Techniques for Rice Production: 2: Impacts on Carbon Sequestration, Soil pH and Grain Yield of Lowlands Rice in Southeastern Nigeria

Abstract

An inland valley of Federal College of Agriculture, Ishiagu, Ebonyi State, research farm was used in 2018 and 2019 cropping seasons to determine the impacts of fields’ preparation techniques on carbon sequestration, soil pH and grain yield of rice in Ishiagu. A randomized complete block design was employed for the study. Field preparation techniques employed include; Cleared, tilled, seedlings-transplanted and hand weeding (C/T/ST//HW); Non-selective herbicide applied, cleared, tilled, seedlings-transplanted and herbicide for weeding (N-H/C/T/ST); Applied non-selective herbicide, cleared, broadcasted seeds and herbicide for weeding (N-H/C/B); Applied Non-selective herbicide, broadcasted and herbicide for weeding (N-H/B); Cleared, tilled, seedlings-transplanted and herbicides for weeding (C/T/ST/S); Applied Non-selective herbicide, cleared, tilled, seedlings-transplanted and hand weeding (NHw/ C/T/ST/Hw). Results showed that C/T/T/HW sequestrated soil carbon higher (37.02 g/m²) than other field techniques in the 1^st year, as N-H/C/B and N-H/C/T/T gave the highest improvement in the 2^nd year. Soil organic carbon (SOC) improvement (1.3443%) in the 1^st year was obtained from C/T/T/HW plots, whereas in the 2^nd year, N-H/C/B plots gave the highest (1.5070%) significant (p < 0.05) increase. Results revealed that C/T/T/HW plots increased pH higher (5.13) in the 1^st year, while in the 2^nd year, N-H/C/T/T gave the highest (5.40) improvement. Findings from this study showed that soil carbon sequestration can be greatly enhanced by the type of rice field management practice(s) adopted during planting and at the time of weed control. It is therefore concluded that, since herbicides application is the most common practice and cheaper approach in the study area, farmers are recommended to use non- selective herbicides to clear the vegetation but use manual weeding operation subsequently in the control of weeds with proper water management which will help in weed control in their rice fields.