Effect of Vermicompost and Biochar of Pruning Waste on Soil Properties and Faba Bean (Vicia faba L.) Yield under Calcareous Soil

Abstract

A two-year field study was conducted to compare the effect of biochar and vermicompost of olive tree pruning waste together with chemical fertilizer on microbial population and soil chemical status and faba bean yield in a calcareous soil in Tarem city, Iran. The treatments included wood biochar (BIC) at two levels of 5 (BIC5) and 10 (BIC10) t ha-1; wood vermicompost (VCM) at two levels of 5 (VCM5) and 10 (VCM10) t ha 1; 50% (NPK50) and 100% (NPK100) recommended chemical fertilizer; along with a control. The results showed that the highest population of total bacteria was obtained from BIC10 (297.8 × 106 CFU/g dry soil), actinomycetes from VCM10 (99.5 × 105 CFU/g dry soil), and fungi from NPK50 (104.5 × 103 CFU/g dry soil). In both years, vermicompost treatments reduced soil pH by 1.6-9.2% compared to control, but biochars showed the highest pH and EC. Organic treatments, especially VCM10 and BIC10, increased the soil organic carbon (OC) compared to the control (by 12.9-35.4%) and NPK (by 57.2-79.1%). Ammonium (NNH4+) and nitrate (N-NO3-) nitrogen of soil decreased in line with increasing the use of biochar (BIC10) and vermicompost (VCM10), but increasing NPK, from NPK50 to NPK100, increased soil N-NH4 + and N NO3 ─ by 21.3% and 10.7%, respectively. In both years, the highest number of pods (45.9 and 57.8 in the first and second year, respectively), number of seeds (187.3 and 240.2 in the first and second year, respectively) and seed yield (1.997 and 2.502 t ha-1 in first and second year, respectively) were obtained from soils treated with VCM10. In addition, the highest amount of N seeds (5.579%), K (0.839%) and Fe (66.3 mg kg-1) was observed in BIC10 and the highest amount of P seeds (0.519%) was observed in VCM10. Totally, organic amendments were superior to chemical fertilizers in terms of improving soil fertility and seed yield.