OPIYO, WOKORACH SAMUEL2026-10-302026-10-302026-10http://hdl.handle.net/20.500.14270/1081Low soil fertility is a global challenge frustrating efforts of enhancing crop productivity. One of the most important plant nutrients often in short supply is nitrogen (N). Crops commonly suffer from N deficiency due to high N lost as nitrous oxide (N2O) gas, low nutrient absorption and accumulation in plant. Farmers who use conservation practices such as use of leaf litter to improve soil fertility suffer poor timing of application or slow mineralization process. Thus, objectives of the study were (i) to determine the effect of conservation agriculture (CA) planting basin, biochar and pigeon pea leaf litter on N2O emission, (ii) to determine the effect of CA planting basin and biochar on the quantity and quality of pigeon pea leaf litter, (iii) to determine the effect of variation of nutrient content of pigeon pea leaf litter on mineralization. For objective 1, field experiment consisting of four treatments; CA + biochar, CA + biochar + leaf litter, CA + leaf litters and control. The experiment was organized in completely randomized design with four replicates to determine effect on N2O emission. There was N2O emission of 10–40 µg N2O-N m⁻² h⁻¹ on average across different conservation agriculture practices that did not differ significantly (p=0.137). For objective 2, an experimental design of randomized complete block design was established to test the effect of conservation agriculture, conservation agriculture plus single application of 4 t/ha biochar, conservation agriculture plus double application of biochar at 2 t/ha followed by 1 t/ha and conventional farming on quantity and quality of leaf litters of pigeon pea. Before treatment, quantity of litter and N content on average was 240 kg/ha and 40 g/kg respectively. However, there was no significant effect of treatments on quantity of leaf litters and amount of N in leaf litters. However, leaf P and K content was affected by treatments. Leaf litter from conservation agriculture and conventional practice had lower content of P and K at 2.7 mg/kg and 39 mg/kg, respectively (p<0.001). The P and K content of litter from conservation agriculture with single and double application of biochar was higher at ~3.9 mg/kg and ~62 mg/kg, respectively. For objective 3, incubation experiment on N mineralization rate of leaf litter from different soil nutrient content was conducted over 14-16-day period. Furthermore, the leaf litter significantly stimulates soil microbial activity, with peak CO₂ evolution occurring at day 12 (p < 0.001). This indicates that most active microbial activity is confined to the initial two weeks of application of the litter. Last, ammonium concentrations peaked at day 12 and then dropped sharply as nitrate levels surged between days 13 and 16 (p < 0.001), confirming the typical mineralization-nitrification sequence, with significant result. This study demonstrates that integrating CA with biochar enhances nutrient retention and availability. Furthermore, understanding variation in the nutrient content of the organic litter is important in planning its application to allow time for mineralization. Thus, mainstreaming pigeon pea as part of soil management will be alternative approach that boosts soil health, nutrient level and productivity of soil.enThesis