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Transformasi Nitrogen dalam Tanah Tergenang: Aplikasi Jerami Padi dan Kompos Jerami Padi Indriyati, Lilik Tri; Sabiham, Supiandi; Darusman, Latifah Kosim; Situmorang, Rykson; Sudarsono, .; Sisworo, Widjang Herry
JOURNAL OF TROPICAL SOILS Vol. 13 No. 3: September 2008
Publisher : UNIVERSITY OF LAMPUNG

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5400/jts.2008.v13i3.189-197

Abstract

The use of organic materials aimed at reducing the dependence on inputs such as chemical fertilizers can contribute to sustainability and improving the low N fertilizer efficiency of rice plants in paddy soils.  Therefore, better understanding of N transformation in flooded soils, particularly the microbial transformation of N-organic amendments to plant-available N and gaseous N forms is needed for most efficient use of soil and organic materials N, for determining the potential of denitrification and for aiding in the selection of N management practices for sustainable agriculture.  The experiments were conducted in the laboratory and glasshouse of Soil Department, Faculty of Agriculture, Bogor Agricultural University.  An incubation experiment was conducted in the laboratory at room temperature during 120 d to analyze the mineralization-immobilization patterns in flooded soils amended with rice straw, rice straw composts 4 mo and 8 mo and their combinations with urea.  The first time of soil flooding, mineral N (N-NH4+ and N-NO3-) concentrations in all of the amended soils sharply decreased and those gradually increase since 7 d of incubation.  It might be due to the reduction of N-NO3- to N2O and N2, and immobilization.  This data was consistent with the data of N2O emission derived from pot experiment.  The high emission of N2O was observed at the first time of soil flooding of the amended soils, and the soils added rice straw showed the largest N2O emission than the other treatments. It might be due to the change of soil condition from aerobic to anaerobic condition, and the higher decomposable C as energy source for denitrifyer contained in rice straw.  Regardless the organic materials added to soils, the longer anaerobic condition, nitrification sharply decreased, so that nitrate availability limits denitrifications.decreased, so that nitrate availability limits denitrifications.
Penentuan Kebutuhan Pupuk Kalium untuk Budidaya Tomat Menggunakan Irigasi Tetes dan Mulsa Polyethylene Amisnaipa, ,; Susila, Anas D.; Situmorang, Rykson; Purnomo, D. Wasgito
Jurnal Agronomi Indonesia (Indonesian Journal of Agronomy) Vol. 37 No. 2 (2009): Jurnal Agronomi Indonesia
Publisher : Indonesia Society of Agronomy (PERAGI) and Department of Agronomy and Horticulture, Faculty of Agriculture, IPB University, Bogor, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (105.717 KB) | DOI: 10.24831/jai.v37i2.1403

Abstract

Tomato var. Ratna was grown with polyethylene mulched and drip irrigation on Inceptisol Dramaga with very low soil K and organic matter during two seasons to K critical concentration, and potassium fertilizer requirement. Experiment used single location approach with three steps of activity.  The first experiment was established in 2004 to develope artificial soil K status by adding K: 0X (0), 1/4X (193.098), 1/2X (386.195), 3/4X (579.293) and X (772.39 kg K2O ha-1), where X was amount of K equal to 772.39 kg K2O ha-1 or 1287.32 kg KCl ha-1.  The second experiment was calibration K study, the experiment arranged in split plot design, with main plot was K status (form first experiment) and sub-plot was K aplication (0, 40, 80, 160, and 320 kg K2O ha-1) in 4 replicated.  Third experiment was optimation of K rate.  The result showed that interval of soil K availability extracted by Morgan Vanema was divided 5  classes,  they were  very low (< 58.25 ppm K), low (58.25-103.25 ppm K), medium (103.25-205.00 ppm K), high (=205 ppm K) and very high (>205.00 ppm K). Potassium recommendation for tomato on Inceptisol with drip irrigation and polyethylene mulch which has very low, low, medium, high and very high K content was 180.20, 131.30 and 82.25 kg K2O ha-1or equal to  300.33, 218.83, and 137.08 KCl ha-1 respectively.   Key words:  Fertilizer, Potassium, calibration,  Lycopersicon esculentum.