Soil Fertility, N2 Fixation and Yield of Chickpea as Influenced by Long-Term Biochar Application under Mung–Chickpea Cropping System

A research study was established at the research farm of the University of Agriculture, Peshawar during winter 2018–2019. Commercial biochars were given to the experimental site from 2014 to summer 2018 and received 0.95, 130 and 60 tons ha−1 of biochar by various treatments viz., (Biochar1) BC1, (Biochar2) BC2, (Biochar3) BC3 and (Biochar4) BC4, respectively. This piece of work was conducted within the same study to find the long-term influence of biochar on the fertility of the soil, fixation of N2, as well as the yie1d of chickpea under a mung–chickpea cropping system. A split plot arrangement was carried out by RCBD (Randomized Complete Block Design) to evaluate the study. Twenty-five kilograms of N ha−1 were given as a starter dosage to every plot. Phosphorous and potassium were applied at two levels (half (45:30 kg ha−1) and full (90:60 kg ha−1) recommended doses) to each of the four biochar treatments. The chickpea crop parameters measured were the numbers and masses of the nodules, N2 fixation and grain yield. Soil parameters recorded were Soil Organic Matter (SOM), total N and mineral N. The aforementioned soil parameters were recorded after harvesting. The results showed that nodulation in chickpea, grain yield and nutrient uptake were significantly enhanced by phosphorous and potassium mineral fertilizers. The application of biochar 95 tons ha−1 significantly enhanced number of nodules i-e (122), however statistically similar response in terms of nodules number was also noted with treatment of 130 tons ha−1. The results further revealed a significant difference in terms of organic matter (OM) (%) between the half and full mineral fertilizer treatments. With the application of 130 tons ha−1 of biochar, the OM enhanced from 1.67% in the control treatment, to 2.59%. However, total and mineral nitrogen were not statistically enhanced by the mineral fertilizer treatment. With regard to biochar treatments, total and mineral N enhanced when compared with the control treatment. The highest total N of 0.082% and mineral nitrogen of 73 mg kg−1 in the soil were recorded at 130 tons ha−1 of biochar, while the lowest total N (0.049%) and mineral nitrogen (54 mg kg−1) in the soil were recorded in the control treatment. The collaborative influence of mineral fertilizers and biochars was found to be generally non-significant for most of the soil and plant parameters. It could be concluded that the aforementioned parameters were greater for treatments receiving biochar at 95 tons or more per hectare over the last several years, and that the combination of lower doses of mineral fertilizers further improved the performance of biochar.