AMELIORASI LAHAN GAMBUT TERDEGRADASI DAN PENGARUHNYA TERHADAP PRODUKSI TANAMAN JAGUNG MANIS

ENI MAFTUAH, SP. MP, Prof. Dr. Ir. Azwar Maas MSc,

2012 | Disertasi | S3 Ilmu Tanah

Pemanfaatan amelioran mutlak diperlukan untuk memperbaiki kondisi gambut terdegradasi sebagai salah satu upaya untuk meningkatkan produktivitas lahannya. Efektivitas bahan amelioran tergantung pada komposisi kimia bahan. Peningkatan efektivitas amelioran dalam memperbaiki kesuburan tanah gambut terdegradasi untuk mendukung produksi tanaman jagung manis dapat dilakukan melalui formulasi beberapa bahan amelioran. Penelitian terdiri dari 4 tahap yaitu: (1) karakterisasi tanah gambut dan bahan amelioran, (2) percobaan inkubasi untuk menentukan potensi amelioran dalam meningkatkan kesuburan tanah gambut terdegradasi, (3) penelitian penentuan jenis dan takaran amelioran yang efektif dalam memperbaiki kesuburan gambut terdegradasi serta pertumbuhan tanaman jagung manis, (4) uji efektivitas jenis dan takaran amelioran terpilih di lahan gambut terdegradasi menggunakan jagung manis, di Ds Kalampangan, Kalimantan Tengah. Lahan gambut terdegradasi yang terpilih untuk penelitian merupakan lahan gambut bekas terbakar pada tahun 1997. Karakteristik lahan di lokasi penelitian antara lain: pH sangat rendah (sekitar 3,53), DHL 0,10 mS cm-1, N tersedia 11,67 mg kg-1 (sangat rendah), P tersedia 6,25 mg kg-1 (sangat rendah) , K tersedia 0,22 cmol(+) kg-1 (rendah), Ca 3,72 cmol(+) kg-1 (rendah), Mg 1,62 cmol(+) kg-1 (rendah), serta pada lapisan bagian atas gambut bersifat hidrofobik. Kemampuan pupuk kandang ayam sebagai amelioran lebih baik dalam memperbaiki kesuburan gambut terdegradasi dibandingkan gulma pertanian in situ, tanah mineral dan purun tikus. Pupuk kandang ayam mempunyai kandungan hara (N, P, K, Ca, Mg) tertinggi dengan rasio C/N < 20 serta kandungan lignin dan selulose paling rendah. Gulma pertanian in situ lebih tinggi kandungan hara N, P, K, Ca dan Mg dibandingkan purun tikus, serta kandungan selulosa dan lignin lebih rendah. Tanah mineral mempunyai kesuburan sangat rendah dengan kandungan N, P, K, dan basa-basa sangat rendah. Jenis dan takaran amelioran mempengaruhi perubahan sifat tanah gambut terdegradasi serta pertumbuhan tanaman jagung manis. Jenis amelioran yang mampu memperbaiki kesuburan tanah, pertumbuhan tanaman dan produksi jagung manis di lahan gambut terdegradasi adalah amelioran yang terdiri: (1) 80% pupuk kandang ayam + 20% dolomit pada takaran 20 t ha-1, (2) 20% pupuk kandang ayam + 20% gulma pertanian in situ + 20% purun tikus + 20% tanah mineral + 20% dolomit pada takaran 15 t ha-1 dan (3) 19,5% pupuk kandang ayam + 71,45% tanah mineral + 9,5% dolomit, pada takaran 20 t ha-1. Amelioran yang direkomendasikan di lahan gambut terdegradasi adalah amelioran yang terdiri 20% pupuk kandang ayam + 20 gulma pertanian in situ + 20% purun tikus + 20% tanah mineral + 20% dolomit pada takaran 15 t ha-1 mampu meningkatkan produksi 42,6% lebih tinggi dibandingkan cara petani di lahan gambut terdegradasi.

Utilization of ameliorant was absolutely necessary to restore the condition and improve the productivity of degraded peatlands. Ameliorant effectiveness depends on the chemical composition of materials. Increased of ameliorant effectiveness in restoring conditions for increase the product of sweet corn on degraded peatlands can be done through the formulation of some materials ameliorant. The research consisted of four stage were: (1) the characteristics of degraded peatlands and ameliorants (2) the laboratory experiment to study the potency of ameliorants for increase the fertility of degraded peat soil, (3) the glass house research to get the type and dose of ameliorants that effective in increasing availability nutrients N, P and K in degraded peat and the growth of corn plants, (4) the effectiveness test of ameliorant type and dose for sweet corn in degraded peat land in Kalampangan village, Kalimantan Tengah. Degraded peat lands that selected for the study was degraded peat land ex-fire in 1997. Characteristics of the land at the sites include: pH is very low (approximately 3.53), EC; 0.103 mS cm-1, available N; 11.67 mg kg-1 (very low), available P; 6.25 mg kg-1 (very low), available K; 0.22 cmol(+) kg-1 (low), Ca; 3.72 cmol(+) kg-1 (low), Mg; 1.62 cmol(+) kg-1 (low), and at the top of the peat layer was hydrophobic. The ability of chicken manure as ameliorant was better than agricultural weed, mineral soil and purun tikus grass. Chicken manure had contains nutrients (N, P, K, Ca, Mg) the highest, ratio of C / N <20 and the content of lignin and cellulose lowest. Agricultural weeds higher content of N, P, K, Ca and Mg compared purun tikus grass, as well as cellulose and lignin content were lower. Mineral soils have very low fertility with the content of N, P, K very low and C/N ratio was quite high. Type and dose ameliorant had been affecting properties of degraded peat soil and the growth of corn plants. Type of ameliorant that can improve soil fertility, increase the availability of N, P, K, the growth and production of corn plants in degraded peatlands were ameliorant formulas: (1) 80% chicken manure + 20% dolomite, at dose 20 t ha-1 (2) 20% chicken manure + 20% agricultural weeds + 20% purun tikus + 20% mineral soil + 20% dolomit, at dose 15 t ha-1 and (3) 19.05% chicken manure + 71.45% mineral soil + 9.5% dolomite at dose 20 t ha-1. Ameliorant that recommended to degraded peat lands was ameliorant formula 20% chicken manure + 20% agricultural weeds + 20% purun tikus + 20% mineral soil + 20% dolomit with dose of 15 t ha-1, that capable to increase is higher compared to farmers in degraded peatlands reached 42.3%.

Kata Kunci : amelioran, karakteristik tanah, gambut terdegradasi, jagung manis