4 ABSTRAK
Analisis laboratorium untuk mengkaji penyediaan Fosfat (P) di Tanah Ultisol akibat pemberian bahan organik. Penelitian ini didesain menggunakan rancangan acak lengkap, menginkubasikan tiga jenis bahan organik; kompos; pupuk kandang ayam dan pupuk hijau dengan dosis 0; 5; 10 dan 15 ton/ha sebanyak tiga ulangan. Diinkubasi selama 20 hari dan senantiasa dalam keadaan kapasitas lapang. Parameter yang diamati adalah pH H2O, kadar C-organik, P-tersedia, P-larut, P-Al, P-Fe dan P-total tanah.
Hasil analisis menunjukkan bahwa pemberian bahan organik meningkatkan nilai pH, kadar C-organik, P-tersedia dan P-larut tanah tetapi menurunkan kadar P-Al dan P-Fe tanah dan tidak berpengaruh pada kadar P-total tanah. Penyediaan P di tanah Ultisol akibat pemberian bahan organik berasal dari P-Al dan P-Fe yang bebas. Pupuk hijau lamtoro (Leucaena leucocephala) lebih baik dari kompos dan pupuk kandang ayam dalam menyediakan P-tersedia.
Kata Kunci: Bahan organik, Fosfat, Ultisol
5 ABSTRACT
Laboratory analysis to study the availability of Phosphate (P) in Ultisols by organic matters application. This study was designed using a complete randomized design, three of organic matters; compost; chicken manure and green manure was applicated to the Ultisols, with dosages 0; 5; 10 and 15 ton/ha, this study replicated three times. Incubated for 20 days and always in field capacity. Parameters measured were soil pH H2O, organic-C, available-P, soluble-P, Al-P,
Fe-P and total-P.
The result of analysis showed that the application of organic matters increases the pH value, levels of organic-C, available-P and soluble-P but decreases levels of Al-P and Fe-P. There was no significance in total soil P levels. Avaibility of P in the Ultisols due to the application of organic matters released from the Al-P and Fe-P. The green manure lamtoro (Leucaena leucocephala) is better than compost and chicken manure in released available-P.
Keywords: Organic matter, Phosphate, Ultisols.