Biological N2 fixation, C accumulation and water-use efficiency (δ13C) of chickpea grown in three different soil types: response to the addition of biochar from poultry litter and acacia

Adding biochar to soil can alter soil properties and thus affect plant growth; however, the effect of biochar on biological nitrogen fixation, carbon accumulation and water-use efficiency of chickpea in tropical soils is not fully understood. Therefore, this study assessed the efficacy of biochar derived from poultry litter (denoted as PLB) and acacia (denoted as ACB) feedstocks on biological nitrogen fixation, carbon accumulation and water-use efficiency (δ13C) of chickpea grown in three contrasting soils of Fernwood (Arenosol) and Griffin (Helvic Acrisol) and Pinedene (Gleyic Acrisol). The biochars were applied at the rate of 0.5%, 1% and 2% (w/w) with control (0%) and replicated four times. Chickpeas grown in PLB treatments in Griffin and Pinedene soils investigated accumulated more N and C, for greater biomass production, resulting in an average total N-fixed of 77 and 52 mg N/plant, respectively. Nitrogen fixation and carbon accumulation of chickpea increased by the addition of 0.5% PLB and ACB in the Fernwood soil. The findings of this study demonstrate the potential of improving N inputs through biological nitrogen fixation with poultry litter biochar application in soils with varying nutrient status and texture, which is important in arid environments with limited N inputs