Teknik Isotop 15N untuk Mengevaluasi Pengaruh Biochar dan Bakteri Penambat Nitrogen terhadap Serapan Nitrogen Tanaman Padi Sawah
Abstract
Abstrak.  Penelitian ini dilakukan untuk menguji pengaruh dari biochar yang berasal dari cangkang kelapa sawit dan juga keefektifan bakteri penambat N pada tanaman padi sawah varietas MIRA 1, dengan menggunakan teknik isotop 15N. Rancangan penelitian yang digunakan yaitu Rancangan Acak Lengkap dengan 3 ulangan. Perlakuan yang diberikan meliputi K0 = Kontrol; K1 = NPK; B1 = Biochar 2 t ha-1; B2 = Biochar 4 t ha-1; B3 = Biochar 2 t ha-1 + NPK;    B4 = Biochar 4 t ha-1 + ½ NPK; B5 = Biochar 2 t ha-1 + pupuk hayati ABC; B6 = Biochar 4 t ha-1 + pupuk hayati ABC; B7 = Biochar 2 t ha-1 + pupuk hayati ABC + ½ NPK; B8 = Biochar 4 t ha-1 + pupuk hayati ABC + ½ NPK; B9 = pupuk hayati ABC. Hasil penelitian menunjukkan bahwa pemberian perlakuan B8 (biochar 4 t ha-1 disertai dengan pupuk hayati ABC dan NPK ½ rekomendasi) mampu memberikan nilai serapan N dan hasil tanaman tertinggi. Teknik 15N menunjukan bahwa sumbangan N tertinggi diperoleh dari perlakuan pupuk K1 (pemupukan NPK 100%). Biochar pada sawah memiliki efek pada peningkatan berat kering biji dan jerami, dan jika disertai dengan pupuk hayati, formula ABC + biochar dapat mengurangi penggunaan pupuk NPK hingga 50%.
Abstract. The aim of the research was to assess the impact of biochar derived from coconut shell and the effectivity of nitrogen fixing bacteria for the lowland rice, MIRA 1 variety, by using 15N isotope technique. The research design was complete randomized design with 3 replications. The treatments included: K0 = control; K1 = NPK; B1 = Biochar 2 t ha-1; B2 = Biochar 4 t ha-1; B3 = Biochar 2 t ha-1 + NPK; B4 = Biochar 4 t ha-1 + ½ NPK; B5 = Biochar 2 t ha-1 + Biofertilizer ABC; B6 = Biochar 4 t ha-1 + Biofertilizer ABC; B7 = Biochar 2 t ha-1 + Biofertilizer ABC + ½ NPK; B8 = Biochar 4 t ha-1 + Biofertilizer ABC + ½ NPK; B9 = Biofertilizer ABC. The result shows that B8 treatment resulted in the highest nitrogen uptake and crop yield. The 15N isotope technique showed that the highest nitrogen supply was derived from K1 treatment (100% NPK fertilizer application. Biochar on paddy fields has an effect on increasing dry weight of grain and dry weight of straw, and if accompanied by biofertilizer of ABC formula + biochar, it can reduce the use of NPK fertilizer by 50%.
