Abstract:
Soil nutrient depletion in lowland rice growing ecologies in Northern Ghana is one of the major causes of low rice yields. Most nutrients applied to enhance the fertility of soil are lost through leaching due to the low CEC of the soils caused mainly by low organic matter and low colloidal clay content of the soils. The application of biochar has been found to improve soil fertility through its enhanced nutrient retention leading to increased nutrient uptake and consequently increased crop yield. The study therefore focused on assessing the potential of using rice husk biochar in combination with different sources and levels of nitrogen on productivity of a soil from lowland rice ecology. The hypothesis was that rice husk biochar in combination with inorganic or organic N will improve the growth and yield of rice and chemical properties of a typic Eutric Gleysol. Soil samples used for the study were collected from a lowland rice growing field in Walewale and some physical and chemical properties of the soil were determined before applying the soil amendments. A pot experiment involving twelve treatments were laid out in a complete randomized design with three replications. Two biochar application rates of 0 t/ha and 50 t/ha were combined factorially with three different rates of nitrogen at 0 kg/ha, 50 kg/ha and 100 kg/ha from two different sources viz, sulfate of ammonia and cowdung. Growth parameters such as weekly plant height and weekly tiller number were monitored one week after transplanting to harvesting. After harvest, the grain yield, straw yield and plant nutrient concentrations were determined. Residual soil analysis was carried out after harvest. The results of the study showed that grain and dry matter yield, N uptake and residual soil total N and C were influenced by amendment with biochar at 50 tons/ha. The combination of biochar at 50 tons per ha with inorganic nitrogen at 100 kg/ha produced the highest grain yield/pot and the highest nitrogen use efficiency (NUE).
