Biochar and nitrogen application rates alter some forage and soil minerals concentrations and soil leachate quality in a semiarid mixed grassland system

In resource-limited agroclimatic environments such as the semiarid and arid regions of the world, mineral undernourishment has been a major limitation to grazing livestock productivity. A soil amendment that has the potential to increase plant mineral uptake and reduce nutrient losses in grassland systems is biochar. The objective of this study was to evaluate the effects of biochar and nitrogen application rates on forage tissue mineral concentrations, soil constituents and leachate quality in a semiarid environment. Treatments were the factorial combination (3 × 3) of three biochar application rates (0, 8.9 and 17.8 Mg/ha) and three N application rates (0, 80 and 120 kg N/ha) arranged in a randomized complete block design experiment with four replications. Treatment means were considered different p ≤ .05. Forage tissue phosphorus concentration was altered by biochar rate × year interaction and a main effect of N rate. Tissue phosphorus concentration was greater at 17.8 Mg biochar/ ha rate than the 0 and 8.9 Mg/ha rates in 2019. For the N rate effect, forage tissue phosphorus concentration was greatest at 0 kg N/ha rate and lowest at 120 kg N/ha rate. The concentration of potassium in the forage was influenced by a biochar rate × N rate interaction. At 120 kg N/ha rate, tissue potassium concentration was greater at 8.9 and 17.8 Mg biochar/ ha rates than the 0 Mg biochar/ha rate. After three years of evaluation, this study demonstrated that biochar used independently or through its interaction with nitrogen fertilizer or year, had a positive influence on the forage minerals phosphorus, potassium, sodium and manganese and the tendency to also positively influenced the forage sulfur and boron concentrations.