Nutrient Availability to Maize Crop (Zea mays L.) in Biochar Amended Alkaline Subtropical Soil

Biochar application variably affects nutrients availability, growth, and yield of crop plants based on their feedstock type and pyrolysis conditions. A pot experiment was carried out to evaluate the effect of biochars prepared from three different feed stocks viz. sugarcane filter cake (SF-BC), farmyard manure (FM-BC), and rice husk (RH-BC), on the availability of the plant nutrients in soil and the growth and nutrient uptake by maize crop (Zea mays L.). The biochars were applied separately to the soil at the rate of 0, 0.25, 0.5, and 1% separately, and the experiment was laid out according to two-factor factorial completely randomized design (CRD) maintaining three replications. Maize variety Monsanto-DK8031 was sown as the test crop. The concentration of total nitrogen (N), nitrate (NO3-N), ammonium (NH4-N), microbial biomass nitrogen (MBN), Olsen phosphorus (P), and extractable K increased with the addition of FM-BC, while the SF-BC increased soil microbial biomass phosphorus (MBP) and micronutrients (Zn, Mn, Cu, Fe) availability in the soil. Moreover, the biochar application significantly improved crop growth parameters (i.e., plant height, fresh plant weight and dry biomass) and also increased plant nutrient concentration and uptake. No negative impact of biochar was observed on plant growth or nutrients concentration. The macronutrient (total N, P, and K) contents and their uptakes were higher in plants grown with RH-BC, while the micronutrient (Mn, Cu, and Fe) contents were higher in plants grown with SF-BC. Biochar as an organic amendment has a great potential to improve soil fertility status and nutrients availability to crop plants in tropical alkaline soils; however, the effectiveness varies with the feed stock type and application rate.