PENINGKATAN EFISIENSI PEMUPUKAN NITROGEN PADI SAWAH DENGAN PENGHAMBAT NITRIFIKASI ALAMI

Joko Pramono, Ir.,MP., Prof. Dr. Ir. Djoko Prajitno, M.Sc.

2013 | Disertasi | S3 Agronomi

Penelitian Peningkatan Efisiensi Pemupukan Nitrogen Padi Sawah dengan Penghambat Nitrifikasi (PN) Alami, bertujuan untuk mendapatkan bahan penghambat nitrifikasi alami, takaran optimum dan dampaknya terhadap efisiensi pemupukan nitrogen pada padi sawah. Penelitian ini terdiri dari empat tahap termasuk penelitian pendahuluan yang dilaksanakan selama 20 bulan mulai September 2008 sampai April 2010. Penelitian di laksanakan di Laboratorium Balingtan Pati, Laboratorium Fakultas Pertanian Universitas Gadjah Mada dan di lahan petani Desa Trirenggo, Kabupaten Bantul. Keempat tahap penelitian meliputi penelitian di laboratorium, penelitian di rumah kaca dan penelitian di lahan petani, dengan menggunakan metode rancangan Acak Lengkap untuk penelitian tahap I dan II, dan penelitian faktorial 3 x 4+1 untuk penelitian tahap III di lahan petani. Hasil penelitian menunjukkan, bahwa (1) Bahan penghambat nitrifikasi yang berasal dari serbuk biji mimba (SBM) memberikan tingkat penghambatan tertinggi sebesar (21,4 %), serbuk kulit kayu bakau (SKKB) sebesar (16,9%), dan serbuk daun kopi (SDK) sebesar 12,3% dibandingkan tanpa pemberian PN, (2) Pemberian PN mampu menghambat nitrifikasi hingga 14 hsa dan menekan pelindian nitrat hingga pengamatan hari ke 14 setelah aplikasi bahan PN. (3) Takaran optimum dua bahan penghambat nitrifikasi terpilih yang menunjukkan kinerja penghambatan nitrifikasi terbaik (SBM dan SKKB) pada 7 hsa, masing-masing 18,30 % dan 21,67%. Pada percobaan kedua (rumah kaca) bahan PN berpengaruh nyata pada komponen hasil jumlah gabah per malai dan hasil gabah. Perlakuan yang memberikan hasil gabah tertinggi adalah N+PN SBM 20% (1,85g urea + 0,37 g PN SBM pot-1), sebesar 87,7 g gabah pot-1 atau meningkat 11,7 % dibandingkan perlakuan tanpa PN. Perlakuan kombinasi pupuk + PN memberikan rata-rata efektivitas pupuk (RAE) sebesar 17,8 % lebih baik dibandingkan pupuk standar. Perlakuan N+PN SBM 20% memberikan nilai efektivitas pupuk, efisiensi agronomi (EAN) dan efisiensi serapan (ESN) tertinggi dan berbeda nyata terhadap perlakuan tanpa penghambat nitrifikasi. Hasil percobaan di lahan petani (tahap III) menunjukkan, bahwa pemberian bahan penghambat nitrifikasi terseleksi (SBM) rata-rata dapat meningkatkan efisiensi agronomi (EAN) sebesar 7,1 % dan efisiensi serapan N (ESN) sebesar 12,8 %. Perlakuan yang memberikan efisiensi terbaik adalah (PN SBM 20 %) dengan AEN (33,75 kg gabah kg-1 N) dan ESN (60 %). Pemberian bahan PN hanya memberikan pengaruh terhadap komponen hasil jumlah anakan produktif, jumlah gabah per rumpun dan jumlah malai per m2, dan tidak berpengaruh terhadap hasil.

Research on increased efficiency of N fertilization in lowland rice by using of natural nitrate inhibitor (NI), aims to ) obtain a natural nitrification inhibitors, optimum dose and its impact on the efficiency of nitrogen fertilization on lowland rice. The study consisted of four phases of research including preliminary research, was carried out for 20 months from September 2008 until April 2010. The research be conducted in Balingtan laboratory, at Pati regency, Agriculture Faculty of Gadjah Mada University and on farm research in Trirenggo village at Bantul district. The four stages of the research include research in the laboratory, research in greenhouses and research in farmers' fields, using a completely randomized design method to study phase I and II, and research factorial 3 x 4 +1 for phase III studies in farmers' fields. The results showed, that (1) NI derived from Neem seed powder (NSP) gave the highest inhibition rate around 21.4% compare to without NI, mangrove bark powder (MBP) around 16.9%, and coffee leaf powder (CLP) 12.3%, (2) The application of NI was able to inhibit nitrification and suppress prevent nitrate leaching until 14 DAA. (3) the optimuml dose of two NI materials selected that showed the best performance of nitrification inhibition are NSP and MBP 18.30% and 21.67% at 7 DAA, respectively. In greenhouse experiments, NI had a significant effect on some yield components (number of productive tillers and number of grains per panicle) and grain yield. The treatment which gave the highest grain yield was N+NSP 20% (1.85 g urea + 0.37 g NI NSP pot-1), amounting to 87.7 g pot-1 of grain, 11.7% higher than treatment without NI. Combinations treatment N fertilizer + NI gave average fertilizer effectiveness (RAE) 17.8% better than standard fertilizer. N+NSP 20% treatment gave the highest effectiveness value of fertilizer, agronomic efficiency N (AEN) and uptake efficiency (UEN), and significantly different from the treatment without NI. Results of experiments in farmers' fields (phase III) showed that additional selected NI (NSP) could increase agronomic efficiency (AEN) 7.1% and N uptake efficiency (UEN) by 12.8%. Treatment which gave the best efficiency was NSP 20% with AEN (33.75 kg grain kg-1 N) and UEN 60%. NI treatment influenced yield components number of productive tillers, grain number per clump and the number of panicles per m2, but it did not significantly affect the yield.

Kata Kunci : penghambat nitrifikasi alami, efisiensi pemupukan N, padi sawah