Pengujian Efektivitas Bahan Pembenah Tanah Dolomit untuk Tanah Masam.

Abstract

One effort to improve acid soil in supporting plants growth is by adding ameliorant such as lime. Lime addition was expected to decrease aluminum ion that can be toxic for plants and increase calcium and magnesium ions contents in acid soil. According to Decree of Minister of Agriculture No.02/pert/HK.060/2/2006 about rules and regulation of distributing soil ameliorant, i. e. each fertilizer or ameliorant should be tested in determining its quality and effectiveness before it is sold, therefore dolomite ameliorant has to be tested before it is traded. Based on the decree, the experiment to determine lime effectiveness needs much time that is incubation for about two months so that inefficient in time, thus a new method for quick test in order to determine the quality of lime is needed, i. e. method of material reactivity test. Lime effectiveness test regarding to method that is mentioned in the decree is conducted by mixing lime into soil with different dosage, those are 0, 0.5, 1.0 and 1.5 times of recomended dosage (1 x exchangeable Al) then all incubated for two months in field capacity condition. Soil sample that was used in this experiment was Podsolik Merah Kuning Jasinga and the experiment object was dolomite. Each treatment was repeated three times. Effect of ameliorant addition was observed by analizing soil samples every week. The observed parameters were pH and exchangeable Al. Whereas, the reactivity experiment method was done by reacting lime with various HCl concentration (0.05 N, 0.1 N and 0.2 N) without heating then shaking them with time variable and titration with NaOH. Reactivity of dolomite was compared with reactivity of CaCO3 pro analysis (p.a) and lime sample. The result of soil incubation experiment showed that dolomite which was added with dosage 1 x exchangeable Al increased soil pH from 4.43 to 4.80 after mixing and became 4.99 in the first week after mixing and also decreased soil exchangeable Al content from 4.43 to 1.35 me/100g after mixing. At the end of incubation period, soil pH became higher and exchangeable Al content became lower than the beginning. Whereas, the experiment of lime reactivity according to method that was used indicated that reactivity of lime sample was much lower than the tested dolomite and reactivity of dolomite was lower than CaCO3 p.a. The result showed that lime sample does not have ability in neutralizing acid but dolomite has a good ability to neutralize acid. The method of ameliorant effectiveness experiment was suitable for quick test in determining the quality of lime.