Response of Rice and Carbon Emission to Application of Ameliorant Dregs in The Peat Soil with Saturation and Unsaturation Condition

Abstract

Fertility of peat land is very poor and makes it not suitable for crop without any high input.  This condition was indicated by the very high soil acidity ( low pH), low availability of macro (N, K, Ca and P), and micro (Cu, Zn, Mn and Bo) nutriens and high cation exchange capacity (CEC) but low base saturation (BS), the presence of toxic organic acid. The main organic acids, as a result of lignin biodegradation and the sources of C-release, are of aromatic group consisting mainly of derivate phenolic acids. The peat soil material was taken at depths from 0 to 30 cm, with weathering rate saprik and dregs from Indah Kiat Pulp and Paper at Perawang, Riau. These experiments using split plot design, the main plot is the condition of the water (unsaturated and saturated) and the subplot is ameliorant dregs consisting of 4 levels (0, 10, 15 and 20 ton ha^-1), each combination was repeated 4 times. The activities were focused on the interaction of water condition and ameliorant dregs, and its influences to growth and yield of rice, C-emission (CO₂ and CH₄). The results showed that the aplication of dregs improves plant growth and increase the yield of rice (weight of dry milled grain) compared without dreg both at unsaturated condition and saturated conditions. The Cabon-release in the forms of CO₂ and CH₄ fluxes in saturated conditions is smaller than unsaturated conditions. The application dreg 10 t ha^-1 increase the number of productive tillers and the weight of milled rice about 35 and 75% compared without dreg on saturated condition, whereas the increase is greater unsaturated conditions about 63 and 80%. The application of dregs 10 t ha^-1 in saturated condition can reduce CO₂ and CH₄ emissions about 18.19% and 93.71% compared without dreg, otherwise the application dreg 10-20 t ha^-1 increase the production of CO₂ and CH₄ in unsaturated conditions.