Pengaruh berat volume dan kelengasan tanah terhadap serapan hara makro dan pertumbuhan tebu pada ultisol
ALYANDRA, Fikri, Prof. Dr. Ir. Azwar Maas, M.Sc
2009 | Tesis | S2 Ilmu TanahBudidaya tebu di lahan kering dengan sistem ratoon (keprasan) dapat mengakibatkan pemampatan pada tanah. Pemampatan tanah menaikkan BV dan menurunkan porositas sehingga air tersedia menurun. Ultisol adalah jenis tanah yang peka terhadap pemampatan tanah karena tekstur dan kemantapan agregatnya. Tujuan penelitian ini adalah mengetahui : (1) Pengaruh BV tanah terhadap pertumbuhan tebu, (2) Pengaruh tingkat kadar lengas terhadap pertumbuhan tebu , dan (3) Interaksi antara berat volume dan kelengasan tanah terhadap pertumbuhan tebu. Penelitian ini juga mencari tahu pengaruh berat volume dan kelengasan tanah terhadap sifat kimia tanah, ketersediaan beberapa unsur hara tanah, kadar hara di jaringan tanaman dan serapan hara. Penelitian dilaksanakan pada bulan Januari – Juli 2009 di rumah kaca Jurusan Tanah, Fakultas Pertanian, Universitas Gadjah Mada, Yogyakarta, menggunakan percobaan pot. Rancangan percobaan yang digunakan adalah rancangan acak lengkap faktorial 3 x 3. Faktor pertama adalah kadar lengas yang terdiri atas tiga aras yaitu, 25% kapasitas lapangan (A1), 100% kapasitas lapangan (A2) dan jenuh air (A3). Faktor kedua adalah berat volume (BV) yang terdiri atas tiga aras yaitu, BV = 1,0 g/cm3 (B1), BV = 1,2 g/cm3 (B2) dan BV = 1,4 g/cm3 (B3). Hasil penelitian menunjukkan bahwa kenaikan tingkat kelengasan tanah secara nyata menaikkan tinggi tanaman, jumlah daun, panjang batang, berat segar trubus dan akar serta berat kering trubus dan akar. Penampilan terbaik tanaman terdapat pada perlakuan A3 dengan tinggi 317,67 cm, daun berjumlah 10,11, panjang batang 147,33 cm, berat basah trubus 810,72 g, berat kering trubus 173,24 g, berat basah akar 101,83 g dan berat kering akar 26,35 g. Kelengasan juga berpengaruh secara nyata terhadap kadar P daun, kadar Mg daun, dan serapan hara N, P, K, Ca, Mg. Makin besar tingkat kelengasan, maka makin besar serapan hara N, P, K, Ca, Mg. Kadar P tertinggi terdapat pada perlakuan A3 dengan 0,22 % berat kering dan kadar Mg tertinggi tertinggi terdapat pada perlakuan A3 dengan 0,14 % berat kering. Kenaikan berat volume secara nyata menaikkan nilai panjang batang, berat basah trubus, dan kadar K daun. Perlakuan B3 menghasilkan batang terpanjang (106,67 cm) dan trubus dengan berat segar paling berat (495,89 g). Interaksi antar faktor terlihat pada pembentukan panjang batang, berat segar dan berat kering trubus, nilai K daun dan serapan N, P, K, Ca, Mg.
Sugarcane cultivation on dry land by ratoon system could cause soil compaction. Soil compaction increases bulk density, decreases porosity and further more decreases available water. Ultisols are a group of soil which are sensitive to soil compaction due to its texture and agregate stability. This research is conducted to investigate (1) Effect of bulk density, (2) Effect of soil water, and (3) Interaction between bulk density and soil water on the growth of sugarcane. This research also investigate the effect of bulk density and soil water on some soil chemical properties, nutrient availability, tissue nutrient concentration and nutrient uptake by sugarcane. The research was held in January untill June 2009 at the green house of Soil Science Department, Faculty of Agriculture, Gadjah Mada University, Yogyakarta, using pot experiment. The experimental design used was factorial complete randomized design. The first factor was soil water comprised of three levels, i.e 25% field capacity (A1), 100% field capacity (A2) and saturated (A3). The second factor was bulk density comprised of three levels i.e 1,0 g/cm3 (B1), 1,2 g/cm3 (B2) and 1,4 g/cm3 (B3). There were 9 treatment combinations with each treatment repeated three times so there were 27 experiment pots. The result showed that the increase of soil water significantly increases plant height, number of leaves, stalk length, shoot fresh weight, root fresh weight, shoot dry weight and root dry weight. The best sugarcane performance were at A3 treatment with 317,67 of plant height, 10,11 number of leaves, 147,33 cm of stalk length, 810,72 g of shoot fresh weight, 173,24 g of shoot dry weight, 101,83 g of root fresh weight and 26,35 g of root dry weight. Soil water also significantly affect P leaf concentration, Mg leaf concentration, and N, P, K, Ca, Mg uptake. The increase of soil water level increases N, P, K, Ca, Mg uptake. The highest P leaf concentration, and Mg leaf concentration (0,22 % dry weight and 0,14 % dry weight) were because of the influence of A3 treatment. The Increase of bulk density significantly increases plant height, shoot fresh weight, potassium leaf concentration and magnesium uptake. B₃ treatment gives the longest stalk (106,67 cm) and shoot with the heaviest fresh weight (495,89 g). Interaction between factors was seen at the formation of stalk length, shoot fresh weight and dry weight, K leaf concentration and N, P, K, Ca Mg adsorption.
Kata Kunci : Sistem ratoon,Pemampatan tanah,Berat volume,Kelengasan tanah,Ultisol,ratoon system,soil compaction,bulk density,soil water,Ultisol.
