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Yearly and seasonal (rainy and dry seasons) variations of CH4 emission from a Sumatra paddy field were measured for 3 years.The mean CH4 emission rates during the growth period were in the range of 16.0-26.1 mg CH4 m -2 h -~ for the chemical fertilizer plots and 23.3-34.9 mg CH4 m -2 h -I for the plots with rice straw application, respectively. The increase in the amounts of CH4 emission by rice straw application were from 1.3 to 1.6 times. There was no significant difference in the mean CH4 emission rates between rainy and dry seasons.Total amounts of CH4 emitted during the period of rice growth were in the ranges of 29.5--48.2 and 43.0-64.6 g CH4 m -2 for the plots applied with chemical fertilizer and those with rice straw application, respectively. Nearly the same amounts of CH4 were emitted in the first and second half of the growth period, irrespective of rice straw application.

The objective of multi years study was to formulate an alternative organic based fertilizer by mixing a fresh manureand phosphate rock with several different grain sizes conducted in the Field Experimental Station of the Universityof Lampung. Both materials of the fresh manure and phosphate rock were obtained from local sources. Five levelsof mixture of fresh manure and phosphate rock, three levels of grain size of phosphate rock, and two kinds ofcomposting technique were factorial set up. The mixture materials were aerobically composted for 12 weeks. Theresults of the first year study show that (a) the optimum ratio of the mixture of fresh manure and phosphate rock was80% to 20% with the optimum of grain size of phosphate rock < 3 mm; (b) 6-8 weeks of incubation of the mixturematerials has been optimally composted under aerobic conditions of the complete mixture of batch compostedtechnique; (c) the quality of the final produced compost was considered to fulfill the requirement of standard criteriaof organic fertilizer; while (d) the quantity of compost recovered up to 75.07% which was a reliable quantity of massproduction of organic fertilizer.[How to Cite: Nugroho SG, Dermiyati, J Lumbanraja, S Triyono, H Ismono, YT Sari and E Ayuandari. 2012. Optimum Ratio of Fresh Manure and Grain Size of Phosphate Rock Mixture in a Formulated Compost for Organomineral NP Fertilizer. J Trop Soils 17 (2) : 121-128. Doi: 10.5400/jts.2012.17.2.121][Permalink/DOI: www.dx.doi.org/10.5400/jts.2012.17.2.121]

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