B. Hendro Sunarminto
Gadjah Mada University

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METHANE EMISSION FROM DIRECT SEEDED RICE UNDER THE INFLUENCES OF RICE STRAW AND NITRIFICATION INHIBITOR

Indonesian Journal of Agricultural Science Vol 13, No 1 (2012): April 2012
Publisher : Indonesian Agency for Agricultural Research and Development - MOA

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Abstract

Incorporation of rice straw into soil is a common practice to improve soil productivity and increase inorganic fertilizer availability. However, this practice could contribute to methane (CH4) emission; one of the greenhouse gases that causes global warming. Nitrification inhibitors such as neem cake and carbofuran may reduce methane emission following application of rice straw. The study aimed to evaluate the application of rice straw and nitrification inhibitor to methane emission in rainfed lowland rice system. A factorial randomized block design was used with three replications. The first factor was rice straw incorporation (5 t ha-1 fresh straw, 5 t ha-1 composted straw), and the second factor was nitrification inhibitor application (20 kg ha-1 neem cake, 20 kg ha-1 carbofuran). The experiment was conducted at rainfed lowland in Pati, Central Java, during 2009/2010 wet season. Ciherang variety was planted as direct seeded rice with spacing of 20 cm x 20 cm in each plot of 4 m x 5 m. The rice straw was treated together with soil tillage, whereas nitrification inhibitor was applied together with urea application. Parameters observed were methane flux, plant height, plant biomass, grain yield, organic C content, and bacterial population in soil. The methane flux and soil organic C were measured at 25, 45, 60, 75, and 95 days after emergence. The results showed that composted rice straw incorporation significantly emitted methane lower (73.2 ± 6.6 kg CH4 ha-1 season-1) compared to the fresh rice straw (93.5 ± 4.0 CH4 ha-1 season-1). Application of nitrification inhibitors neem cake and carbofuran reduced methane emission as much as 20.7 and 15.4 kg CH4 ha-1 season-1, respectively. Under direct seeded rice system, methane flux level correlated with plant biomass as shown by linear regression of Y = 0.0015 X + 0.0575 (R2 = 0.2305, n = 27). This means that higher plant biomass produced more methane flux. The study indicates that application of nitrification inhibitors such as neem cake is prospective in decreasing methane emission from direct seeded rice cropping. 

NITROUS OXIDE EMISSION AND NITROGEN UPTAKE AFFECTED BY SOIL AMENDMENT AND NEMATICIDE IN RAINFED RICE SOILS AT CENTRAL JAVA

Indonesian Journal of Agricultural Science Vol 14, No 2 (2013): October 2013
Publisher : Indonesian Agency for Agricultural Research and Development - MOA

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Abstract

Rice cultivation is one of the antropogenic sources of nitrous oxide (N2O) emission that is produced by microbiological nitrification-denitrification processes. Incorporating soil amendment in rainfed rice soil attempted to increase soil productivity, while nematicide application aimed to maintain root growth system. Incorporating soil amendment and nematicide application are predicted to suppress N2O production in lowland rice. The objective of this research was to study the interaction of soil organic amendment and nematicide on N2O emission and nitrogen uptake from rainfed lowland rice soils. A field experiment was conducted in rainfed lowland rice soils during 2010/2011 wet season (direct seeded rice) and 2011 dry season (transplanted rice). The 3 x 3 factorial trial was arranged in a randomized completely block design with three replications. The first factor was soil amendment consisted of without rice straw, fresh rice straw and composted rice straw. The second factor was nematicide application consisted of without nematicide, neemcake and carbofuran. Variables measured were N2O flux, rice grain yield and nitrogen uptake. Incorporation of fresh and composted rice straws reduced N2O flux about 49.2% and 59.9% in transplanted rice, and 32.9% and 28.2% in direct seeded rice, respectively. The neemcake application reduced N2O emission about 44-50%, while carbofuran application decreased N2O emission by 23-35%. Neemcake has a good potential as nitrification inhibitor of N2O emission, so the neem trees have a prospect to be cultivated intensively. The reduction of N2O emission was effective in direct seeded rice system with the application of neemcake and fresh rice straw, however, in transplanted rice system it was effective with neemcake and composted rice straw applications.