Agricultural waste-based modified biochars differentially affected the soil properties, growth, and nutrient accumulation by maize (Zea mays L.) plants

Biochar (BC) is an organic compound formed by the pyrolysis of organic wastes. Application of BCs as soil
amendments has many benefits including carbon sequestration, enhanced soil fertility and sustainable agriculture
production. In the present study, we acidified the different BCs prepared from rice straw, rice husk, wheat straw,
cotton stalk, poultry manure, sugarcane press mud and vegetable waste; following which, we applied them in a
series of pot experiments. Comparisons were made between acidified and non- acidified BCs for their effects on
seed germination, soil properties (EC, pH) nutrient contents (P, K, Na) and organic matter. The treatments comprised
of a control, and all above-described BCs (acidified as well as non-acidified) applied to soil at the rate of 1% (w/w).
The maize crop was selected as a test crop. The results showed that acidified poultry manure BC significantly
improved germination percentage, shoot length, and biomass of maize seedlings as compared to other BCs and
their respective control plants. However, acidified BCs caused a significant decrease in nutrient contents (P, K, Na) of
soil,maize seedlings, and the soil organic matter contents as compared to non- acidified BCs. But when compared
with control treatments, all BCs treatments (acidified and non-acidified) delivered higher levels of nutrients and
organic matter contents. It was concluded that none of the BCs (acidified and non-acidified) had caused negative
effect on soil conditions and growth of maize. In addition, the acidification of BC prior to its application to alkaline
soils might had altered soil chemistry and delivered better maize growth. Moving forward, more research is needed
to understand the long-term effects of modified BCs on nutrient dynamics in different soils. In addition, the
possible effects of BC application timings, application rates, particle size, and crop species have to be evaluated
systemtically.