Soil amelioration using several types of humic substances extracted from andisol, spodosol, peat and lignite to increase the growth of corn plants (Zea mays)

Humic substances are products formed during the decomposition process of organic maerials which can be found in aquatic, sedimentary and soil environments. Humic substances can be used as an ameliorant due to its important roles in improving soil fertility and plant growth. The aim of the study was to determine the mechanism of humic substances in increase the growth of maize plants; to obtain the optimum types and doses of humic in increasing plant growth. The research was conducted in a greenhouse of IPB. The study used a completely randomized design (CRD) which consists of two treatments, namely humic types (Andisol, Spodosol, peat and lignite) and humic doses (15 and 30 liters/ha). The results showed that the administration of humic acid from lignite at a dose of 30 liters/ha was the best treatment to increase the growth of corn plants, which was characterized by better stimulation of leaf width, number of leaves, plant biomass weight, and root dry weight. Thus, humic substances are useful in improving the growth and productivity of corn plants.