EFFECT OF WATER AND ORGANIC FERTILIZER MANAGEMENTS ON SOIL REDOX POTENTIAL, NITROGEN UPTAKE, AND RICE PERFORMANCES UNDER SYSTEM OF RICE INTENSIFICATION

RIZKI MAFTUKHAH, Prof. Dr. Ir. Sigit Supadmo Arif, M.Eng.

2014 | Tesis | S2 Teknik Pertanian

Pengelolaan air dan pupuk organik akan berpengaruh terhadap ketersediaan nutrisi dalam tanah dan produktivitas padi. Peningkatan efisiensi input pada produksi padi perlu ditingkatkan karena air yang terbatas, harga pupuk yang tinggi, dan dampak negatif dari penggunaan input kimia. System of rice intensification (SRI) adalah salah satu sistem yang direkomendasikan dengan irigasi terputus-putus, tanam satu bibit, tanam bibit muda, jarak lebar, dan menggunakan pupuk organik. Penelitian ini bertujuan untuk mempelajari pengaruh pengelolaan air dan pupuk organik terhadap kimia tanah (potensial redoks, nitrogen total, dan besi tersedia) dan produksi padi. Selain itu, juga dikembangkan model sederhana penyerapan nitrogen oleh tanaman dengan keseimbangan air. Penelitian pot dilakukan dengan kerangka kerja SRI dengan irigasi genangan terus-menerus (CF), terputus-putus (IT), dan kapasitas lapang (FC); diinteraksi dengan empat dosis pemupukan organik yang berbeda (F100, F50, F0, dan LF). Hasil penelitian menunjukkan bahwa soil Eh berbeda nyata antara tiga pengelolaan air (p < 0.05), dimana FC memiliki nilai tertinggi diikuti oleh IT dan CF. Namun, pupuk organik tidak berbeda nyata. Nitrogen total dan besi tersedia mengalami penurunan selama penelitian. Jumlah anakan meningkat signifikan pada perlakuan IT daripada CF dan FC (p < 0.05). Namun, pengelolaan air dan pupuk organik tidak berpengaruh nyata terhadap tinggi tanaman. Hasil ini berdampak pada produksi padi dan biomasa, dimana IT secara signifikan berdampak positif terhadap produksi dan biomassa. Penambahan pupuk organik secara signifikan menurunkan jumlah anakan dan berdampak negatif terhadap produksi dan biomasa. Selanjutnya, model penyerapan nitrogen oleh tanaman padi menunjukkan bahwa IT memiliki nilai error yang rendah (nilai prediksi hamper sama dengan observasi). Penelitian ini menggambarkan bahwa irigasi terputusputus memberikan lingkungan yang sesuai untuk tanaman padi dan memerlukan waktu untuk meningkatkan produksi dengan menggunakan pupuk organik. Pengaruh pengelolaan air dan pupuk organik harus diteliti secara terus-menerus pada lahan sawah untuk mengevaluasi kesuburan tanah dan produksi padi pada periode yang panjang. Kata kunci: air, pupuk organik, potensial redoks ,penyerapan nitrogen,produksi padi

Water and fertilizer managements on rice production system affected the change of nutrient availability of soil and rice yield. Regarding on water scarcity, high fertilizer cost, and negative environmental impacts due to high agrochemicals, it’s necessary to improve resource use efficiency on rice cultivation. Recently, system of rice intensification (SRI) is the recommendations which use intermittent irrigation, single seedlings, early transplanting, wide spacing, and organic fertilizer. The aims of this study are to learn the effect of different water and organic fertilization managements on soil chemical properties (redox potential, total nitrogen, and available iron) and rice performances. We also develop a simple model of nitrogen uptake by rice plant via water balance. Pot experiments were conducted under SRI framework with continuous flooding (CF), intermittent (IT), and field capacity (FC) irrigation; together with four different doses of organic fertilization (F100, F50, F0, and LF). Our experiment resulted soil Eh was significantly different between three water management treatments (p < 0.05) where FC resulted highest soil Eh, followed by IT and CF; but organic fertilization was not significant. Total nitrogen and available iron were decreased during experiment. Under IT condition, number of tillers was significantly higher than CF and FC conditions (p < 0.05). On the other hand, water management and organic fertilization had no significant effect on plant height. This result also affected on biomass and rice yield; where IT condition significantly increased yield and biomass followed by CF and FC due to number of tillers. By added organic fertilizer, number of tiller was significantly reduced and negatively affected on yield and biomass. Further, nitrogen uptake modeling resulted that Standard error (STE) of IT was low which means the value of prediction close to observation data. Present study describes that IT condition provides the good environment on rice plant and need times to improve productivity by used organic fertilizer. The effects of water and organic fertilizer managements should be examined continuously in rice field to evaluate soil fertility and rice performances on long-term period. Key words: water, organic fertilizer, redox potential, nitrogen uptake, yield

Kata Kunci : air, pupuk organik, potensial redoks ,penyerapan nitrogen,produksi padi; water, organic fertilizer, redox potential, nitrogen uptake, yield