Effectiveness of cattle dung biogas digestate on spinach growth and nutrient uptake

New farming techniques should be introduced to improve yield quality and quantity while taking preservation of the environment into consideration. This study investigated effectiveness of cattle dung biogas digestate on spinach growth and nutrient uptake. Spinach was grown with cattle dung biogas digestate (BD), inorganic fertiliser (IF) and unfertilised control (CO) treatments under complete randomised design field conditions. Spinach planted under BD showed significantly higher growth in terms of plant height and number of leaves compared to spinach under CO and IF. A linear relationship between leaf numbers and leaf area index (LAI) (R² 0.691, p < 0.0001) was established for the study. Cattle dung biogas digestate (BD) plants produced significantly the longest roots followed by IF plants. The IF plants produced more biomass per rooting depth (0.85 g cm^-1) than BD (0.61 g cm^-1) and CO (0.35 g cm^-1). Regarding macronutrient content of the spinach leaves, significant differences were only observed for potassium (K) in the order of IF (8.6 g kg^-1), BD (6.8 g kg^-1), and CO (6.7 g kg^-1). Significantly higher amounts of zinc (Zn²⁺) accumulated in spinach leaves under BD compared to IF and CO. Fertilising spinach with BD improves growth and development just as much as IF. Additional benefits include improving nutrient content of the spinach, assisting with environmental preservation and decreasing production cost.