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Perubahan Beberapa Sifat Fisika-Mekanika Tanah Akibat Lintasan Traktor pada Lahan dengan Berbagai Kemiringan

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Penelitian bertujuan untuk menelaah sejauh mana peningkatan frekuensi lintasan traktor dalam pengolahan tanah di lahan-lahan miring yang dapat menurunkan stabilitas agregat tanah dan produktivitas tanah telah dilakukan dengan mengamati dan menganalisis perubahan sifat fisika-mekanika tanah di bawah jejak lintasan roda traktor poros-dua. Penelitian ini dilaksanakan dari bulan April sampai dengan bulan Oktober 2004 pada tanah Fluventic Eutrudepts yang berada pada ketinggian 751 m di atas permukaan laut. Metode penelitian yang digunakan mencakup: 1) analisis sidik ragam berdasarkan rancangan acak terpisah dengan pola faktorial, terutama untuk mengamati pengaruh perlakuan terhadap produktivitas lahan yang direpresentasikan oleh kedelai (Glycin max L.). Rancangan ini terdiri dari 3 taraf perlakuan kemiringan lahan sebagai petak utama (K), yaitu; k1 = 0 %-5 % (relatif datar), k2 = 6% -10 % (agak miring), dan k3 = 11 %-15 % (miring/kritis), dan 6 taraf perlakuan frekuensi lintasan pengolahan sebagai anak petak (L), yaitu: l0 = tanpa lintasan, l1 = satu kali lintasan, l2 = tiga kali lintasan, l3 = lima kali lintasan, l4 = tujuh kali lintasan, dan l5 = sembilan kali lintasan. Masing-masing perlakuan diulang dua kali; dan (2) analisis regresi dan korelasi, digunakan untuk mengamati hubungan antara frekuensi lalu-lintas pengolahan tanah dengan perubahan sifat fisika- mekanika tanah sebagai indikator perubahan stabilitas dan produktivitas lahan.Variabel yang diamati adalah : bobot isi tanah, porositas total, indeks stabilitas agregat tanah, permeabilitas tanah, konsistensi tanah, indeks plastisitas tanah, erodibilitas tanah, laju infiltrasi,indeks kerucut tanah, tahanan gesek, dan produktivitas lahan dengan indikator komponen dan hasil kedelai, yaitu; panjang akar, bobot akar, dan hasil kedelai. Hasil penelitian secara umum mengindikasikan bahwa persentase maksimal perubahan sifat fisik dan mekanik tanah yang terjadi di kemiringan k1, k2 dan k3 pada lintasan pengolahan l2 sampai l4 masih dapat ditolerir, karena kestabilan lahan berada pada nilai IS >30 dan dengan hasil kedelai, walau rendah, masih bervariasi pada tingkat lokal (hk 0,6-1,9 ton/ha). Dari hasil "analisis sidik ragam" hasil tanaman kedelai berinteraksi secara nyata pada l0-l5 dan k1-k3. Secara kuantitatif hasil penelitian menunjukkan bahwa perubahan sifat fisik-mekanik tanah dan semua komponen pertumbuhan serta hasil kedelai berbeda nyata pada peningkatan frekuensi lintasan dan kemiringan lahan. Sedangkan secara kualitatif, dari hasil analisis regresi-korelasi, indikasi di atas menunjukkan adanya hubungan polinomial atas hasil kedelai dan indeks stabilitas agregat dengan reliabilitas R2 dari 0,96 sampai 1.00 pada peningkatan frekuensi lintasan l0-l5 di tiga kemiringan lahan k1-k3. 

The research aimed to investigate how far increasing frequency of tractor traffic tillage on slopy ground could deteriorate land stability and soil productivity has been carried out by observing and analyzing the changes of soil physical-mechanical properties underneath wheel tracks of a 2-WD tractor. The experiment was conducted from April to October 2004 on a Fluventic Eutrudepts soil situated at an altitude of 751 m above sea level. Research method employed, encompassing: (1) variance analysis due to factorial split-plot random design, to observe the effect of the treatments on soil productivity as indicated by soybean plant (Glycin max L.). The design consisted of three levels of treatments of land slope as the main plots, where: k1 = 0 %-5 % (relatively flat), k2 = 6 %-10 % (rather slopy), dan k3 = 11%-15 % (slopy/critical), and six levels of treatments of traffic tillage frequency as split plots, where: l0 = no traffic, l1 = one time traffic, l2 = three times traffic, l3 = five times traffic, l4 = seven times traffic, and l5 = nine times traffic, each at two replications, respectively; and (2) regression and corelation analysis that was used to observe the relation of traffic tillage frequency and changes of soil physical-mechanical properties as indications of land stability and productivity changes. Data observed were: soil bulk density, total porosity, stability index of soil aggregates, soil permeability, moisture content, soil consistency, soil plasticity, soil erodibilit, infiltration rate, soil one index, soil shear strength, and land productivity indicated by yield components of soybean plant, i.e.; root length, root weight, and yield of soybean plant. Results of the research generally indicated that maximum percentage of soil physical-mechanical changes occurred in k1 to k3 at l2 was tolerable for its soil stability index was greater than 30 in which the yield of soybean - relatively low though, varied at the local level within 0.6-1.9 tonnes a hectare. Obtained from "variance analysis" the yield of soybean interacted significantly at l0-l5 as well as at k1-k3. Quantitatively, the results showed that the changes of soil physical-mechanical properties as well as growth components and yield of soybean were significantly different at increasing frequency of tillage traffic and land slopes. While qualitatively, obtained from regression-correlation analysis the above indication showed polynomial relations of a reliability R2 of 0.96 to 1.00 for yield of soybean plant and stability index of soil aggregates at increasing frequency of traffic tillage of l0-l5 in the three land slopes of k1-k3..

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D975

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Bandung : ., 2005

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Indonesia

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NONE

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