Pemberian Kotoran Sapi pada Pertanaman Jagung (Zea mays) : Dinamika Perubahan Kadar Karbon organik dan Nitrogen tersedia pada Ultisol Gunung Sindur, Jawa Barat.

Abstract

The research entitled The application of Cow Dung on Corn (Zea Mays) Cultivation: The Dynamic of Changes in Organic Carbon (C) and Available Nitrogen (N) Content in Ultisol Gunung Sindur was conducted in Cibadung village, Gunung Sindur, West Java. Chemical Analyses were conducted in Laboratory of Soil Chemistry and Fertility Department of Soil Science and Land Resource, Faculty of Agriculture, Bogor Agricultural University. The objectives of this research were to evaluate the dynamic of changes in Organic C and available N (ammonium and nitrate) in Ultisol Gunung Sindur treated by cow dung on corn cultivation. The treatments were 0 ton ha-1 (control plot) and 20 ton ha-1 of cow dung in air air-dried condition. The soil samples collection were conducted at 1st, 2nd, 3th, 4th, 6th, 8th, 10th and 14th week after planting in root zone. Organic C content in plot treated by 20 ton ha-1 of cow dung increased with time of soil samples collection and their values were always higher than those of control plot up to 6th week. The equilibrium where the content of organic C of control and plot treated by 20 ton ha-1 of cow dung were similar and constant, occured at 14th week after planting. Ammonium content in plot treated by 20 ton ha-1 of cow dung increased with time of soil samples collection and their values were always higher than those of control plot up to 14th week. Similar to organic C content, the equilibrium was reached at 14th week after planting. The first order kinetic equation coud not be used to simulate the data of ammonium. The Nitrate content increased with time of soil samples collection. The nitrate contents in control plot and plot treated with 20 ton ha-1 of cow dung as well, were always higher than those of ammonium in all time of soil samples collection. The first order kinetic equation revealed that in control plot N which was potential to mineralize to be nitrate was 494 mg kg-1 with rate constant 0.61 week-1 while in plot treated with 20 ton ha-1 of cow dung, N which was potential to mineralize to be nitrate was 620 mg kg-1 with rate constant 0.41 week-1. As for availabe N (ammonium + nitrate), N which was potential to mineralize to be available N in control plot was 538 mg kg-1 with rate constant 0.63 week-1 while in plot treated with 20 ton ha-1 of cow dung N which was potential to mineralize to be available N was 665 mg kg-1 with rate constant 0.46 week-1. The first order kinetic equation also revealed that N from 20 ton ha-1 will fully mineralize to be nitrate and available N at 14th week after planting. The results suggested that equilibrium of application of 20 ton ha-1 cow dung on corn plantation in Ultisol Gunung Sindur for organic C, amonium, nitrate and available N occured at 14th week. N mineralization to be nitrate and available N was simulated well by first order kinetic equation.

Penelitian Pemberian Kotoran Sapi pada Pertanaman Jagung (Zea mays) : Dinamika Perubahan Kadar karbon (C) organik dan nitrogen (N) tersedia pada Ultisol Gunung Sindur ini dilaksanakan di Desa Cibadung, Gunung sindur, Jawa Barat, sementara analisis sifat kimia tanah dilaksanakan di Laboratorium Kimia dan Kesuburan Tanah, Departemen Ilmu Tanah dan Sumberdaya Lahan, Fakultas Pertanian Institut Pertanian Bogor. Penelitian ini bertujuan untuk mengetahui dinamika perubahan kadar karbon organik dan juga kadar nitrogen tersedia (ammonium dan nitrat) pada tanah Ultisol Gunung Sindur yang diberi perlakuan kotoran sapi pada pertanaman jagung. Perlakuan yang diberikan adalah 0 ton ha-1 dan 20 ton ha-1 kotoran sapi dalam kondisi kering udara. Pengambilan sampel tanah dilakukan pada minggu ke-1, 2, 3, 4, 6, 8, 10, dan 14 pada daerah perakaran. Kadar C-organik pada petak yang diberikan 20 ton ha-1 kotoran sapi meningkat dan selalu lebih tinggi dibandingkan petak kontrol sampai minggu ke-6. Kesetimbangan tercapai dimana kadar karbon organik pada petak yang diberikan 20 ton-1 kotoran sapi dan petak kontrol sama pada minggu ke-14. Kadar amonium petak yang diberikan 20 ton ha-1 kotoran sapi meningkat dan selalu lebih tinggi dibandingkan petak kontrol sampai minggu ke-14 dimana pada minggu ke-14 kadar amonium petak yang diberikan 20 ton ha-1 kotoran sapi dan petak kontrol sama. Persamaan first order kinetic tidak dapat digunakan untuk mensimulasi data amonium. Kadar nitrat meningkat dengan meningkatnya minggu inkubasi. Kadar nitrat selalu lebih tinggi dibandingkan dengan nilai amonium baik pada petak kontrol dan petak yang diberikan 20 ton ha-1 kotoran sapi. Dengan persamaan first order kinetic didapat bahwa N yang berpotensi termineralisasi menjadi nitrat pada kontrol adalah 494 mg kg-1 dengan konstanta kecepatan 0.61 minggu-1 sementara pada petak yang diberikan 20 ton ha-1 kotoran sapi adalah 620 mg kg-1 dengan konstanta kecepatan 0.41 minggu-1. Untuk N tersedia (amonium + nitrat), N yang berpotensi termineralisasi menjadi N-tersedia adalah 538 mg kg-1 dengan konstanta kecepatan 0.63 minggu-1 sementara petak yang diberikan 20 ton ha-1 kotoran sapi adalah 665 mg kg-1 dengan konstanta kecepatan 0.46 minggu-1. Dari hasil penelitian ini bahwa N yang berpotensi termineralisasi baik menjadi nitrat ataupun N-tersedia pada perlakuan 20 ton ha-1 dibawah pertanaman jagung pada Ultisol Gunung Sindur habis termineralisasi pada minggu ke-14. Hasil ini menunjukan di Ultisol Gunung Sindur kesetimbangan pemberian 20 ton ha-1 kotoran sapi pada pertanaman jagung untuk karbon organik, amonium, nitrat, dan nitrogen tersedia tercapai pada minggu ke-14. Mineralisasi N-organik menjadi nitrat dan N-tersedia dapat dengan baik disimulasikan dengan persamaan first order kinetic.