Abstract

Owing to the benefits of biochar in soil sustainability, this study considered the effect of applying rice husk biochar as a substitute for inorganic fertilizer on soil properties and maize growth in Ghana. Six treatments (comprising of five rice husk biochar rates and one rate of NPK inorganic fertilizer as control) with four replicates in a pot experiment and “Obaatanpa” maize variety were used for the study. Results showed that the incorporation of biochar increased soil pH, organic carbon and effective cation exchange capacity for the various treatments which were higher than NPK treatment. Generally, 50 t/ha biochar applied at the time of planting recorded the lowest soil chemical properties which resulted in reduced maize germination count and yield while 50 t/ha biochar applied 2 weeks before planting improved soil chemical properties. Biochar increased all soil chemical properties analyzed more than NPK except for available phosphorus and potassium, which are key nutrients for maize growth. The maize yield in the biochar treatments was significantly lower (by 300%) than the NPK treatment, suggesting that biochar application in the short term, although could increase soil chemical properties, does not translate into essential nutrients available for improving maize yield. Therefore, quantity and incubation time for rice husk biochar before planting has a significant impact on soil nutrient and yield of maize. Future studies should consider the application of biochar at a longer period before planting and in combination with inorganic fertilizer as a top dressing and residual biochar for maize production.

摘要

由于生物炭对土壤可持续性的好处，本研究考虑了使用稻壳生物炭替代无机肥料对加纳土壤特性和玉米生长的影响。在盆栽实验中有6个处理（包括5种稻壳生物炭比率和1种NPK无机肥料比率作为对照）和4个重复样本玉米品种用于研究。结果表明，生物炭的掺入提高了土壤处理的pH值，有机碳和有效的阳离子交换能力，高于NPK处理。通常，种植时施用的50吨/公顷生物炭记录了最低的土壤化学特性，这导致玉米发芽数和单产下降，而种植前两周施用了50吨/公顷生物炭，改善了土壤化学特性。除了可利用的磷和钾（磷是玉米生长的关键营养素）外，生物碳比氮磷钾提高了所有土壤化学性质，而氮磷钾的施用量却比氮磷钾高。生物炭处理中的玉米产量显着低于NPK处理（降低了300％），这表明在短期内施用生物炭虽然可以提高土壤化学性质，不能转化为可用于提高玉米产量的基本营养素。因此，种植前稻壳生物炭的数量和孵育时间对玉米的土壤养分和产量有重要影响。未来的研究应考虑在种植前较长时间使用生物炭，并与无机肥料配合使用作为表土和残留的生物炭来生产玉米。