PENETAPAN MINIMUM DATA SET DAN INDEKS MUTU TANAH SEBAGAI LANDASAN PENGELOLAAN LAHAN BERKELANJUTAN

Anna Maria Makalew, Ir. M.Sc., Prof. Dr. Ir. Bambang Hendro Sunarminto, SU.

2011 | Disertasi | S3 Ilmu Tanah

Mutu tanah adalah kapasitas tanah berfungsi, berubah sesuai pengelolaan dan penggunaan lahan. Mutu tanah tidak dapat diukur secara langsung, sehingga perlu ditentukan indikator fisik, kimia, dan biologi yang secara bersama-sama memberikan pengukuran menyeluruh mutu tanah, disebut minimum data set (MDS). Tujuan penelitian adalah mengidentifikasi faktor mutu tanah di lokasi penelitian; menyeleksi atribut tanah dalam faktor mutu tanah untuk selanjutnya menentukan MDS; menetapkan indeks mutu tanah sebagai alat ukur perubahan mutu tanah akibat pengelolaan dan penggunaan lahan; mengamati pengaruh mutu tanah pada hasil jagung (ton ha-1). Lokasi penelitian, Kecamatan Panyipatan Kabupaten Tanah Laut Provinsi Kalimantan, ditentukan sesuai prosedur purpossive stratified sampling. Berdasarkan prinsip pertanian berkelanjutan, sesuai untuk tanah masam, mudah dipasarkan, dan disenangi petani, 3 varietas jagung, Kima, Sukmaraga, dan Bisi-2 ditanam pada 3 lingkungan tanah Typic Hapludox, Plinthic Kandiudult, dan Plinthic Hapludox menggunakan rancangan kelompok acak lengkap dengan 3 ulangan. Pengamatan tanaman dilakukan pada saat silking, yaitu analisis kandungan N, P, dan K jaringan daun serta saat panen, yaitu hasil pipilan kering jagung (ton ha-1) sebagai endpoints. Contoh tanah diambil dari permukaan tanah (0-15 cm sampai 0-20 cm) pada awal penelitian, periode silking, dan saat panen. Sesuai prosedur standar, diteliti 22 parameter biofisik tanah lahan jagung. Faktor mutu tanah diidentifikasi sesuai prosedur reduksi data secara statistik memakai analisis faktor (PFA). Selanjutnya, MDS ditetapkan melalui intersection MDS hasil prosedur reduksi data secara statistik menggunakan prosedur ANOVA dan PFA terhadap 17 atribut dinamis tanah dan MDS hasil expert opinion. Expert opinion dan indeks mutu tanah (IMT) memakai prosedur sesuai Soil Management Assessment Framework (SMAF). Pengaruh IMT terhadap hasil jagung diamati memakai ANOVA(PROC GLM, SAS 9.1). Hasil penelitian mengungkapkan bahwa terdapat 4 faktor mutu tanah lahan jagung Kecamatan Panyipatan. Pertama, faktor perkembangan tanah dengan komposisi P-total (mg 100 g-1), berat volume (BD, g cm-3), kapasitas lengas tersedia (AWC, %), karbon organik tanah (SOC, %). Ke dua, faktor kesuburan tanah dengan komposisi P-tersedia (ppm), pH tanah, dan Ca-tertukarkan (cmol(+) kg-1). Ke tiga, faktor kesuburan tanah dengan komposisi K-tertukarkan (cmol(+) kg-1) dan Mg-tertukarkan (cmol(+) kg-1). Ke empat, faktor bahan organik tanah, yaitu N (%). Indikator mutu tanah MDS meliputi berat volume (BD, g cm-3), kapasitas lengas tersedia (AWC, %), pH tanah, P-tersedia, karbon organik tanah (SOC, %), dan pori terisi air (WFPS, %). IMT ketiga lingkungan tanah, Typic Hapludox adalah 75; Plinthic Kandiudult adalah 71; Plinthic Hapludox adalah 57. Mutu tanah tidak mempengaruhi hasil pipilan kering jagung (ton ha-1).

Soil quality is the capacity of soil to function. Soil quality changes due to management and land use. Soil quality cannot be measured directly. It is required to set soil physical, chemical, and biological indicators, which together provide a comprehensive measurement of soil quality, called the minimum data set (MDS). Research objectives were to identify the soil quality factors; select soil attributes of soil quality factors for determining the MDS; establish research sites soil quality index (SQI) as measurement of changes in soil quality due to management and land use; assess the influence of soil quality on corn yield (t ha-1). Research area, Panyipatan Sub district Tanah Laut Regency South Kalimantan Province was determined using purpossive stratified sampling procedure. Based on the principles of sustainable agriculture, three varieties of corn, Kima, Sukmaraga, and Bisi-2 was grown in three environments, Typic Hapludox, Plinthic Kandiudult, and Plinthic Hapludox using completely randomized block design, each group consisted of three replications. Observations were carried out at silking period, viz. content of N, P, and K of leaf tissues, and at harvest time, the corn yield (ton ha-1) as endpoints. Soil samples of surface soil (0-15 to 0-20 cm) were taken three times, at the beginning of the study, the silking period, and at harvest time. Twenty-two biophysical parameters of land were investigated. Soil quality factors were identified using statistical procedures of data reduction, principal factor analysis (PFA). Furthermore, the MDS was determined through intersection of MDS resulted from statistical data reduction PFA of more than 17 dynamic soil attributes and MDS resulted from expert opinion of the Soil Management Assessment Framework (SMAF). SQI index was determined according to the procedure of SMAF. Effects of soil quality on corn yield were examined using ANOVA (PROC GLM, SAS 9.1). The Research revealed that soil quality factors of Panyipatan District corn land consisted of four common factors. First, soil development factor with composition of P-total (mg 100 g-1), bulk density (BD, g cm-3), available water capacity (AWC, %), and soil organic carbon (SOC, %). Second, soil fertility factor with composition P-available (ppm), soil pH, and Ca-exch (cmol (+) kg-1). Third, soil fertility factor with composition of K-exch (+) kg-1) and Mg-exch (+) kg-1). Fourth, soil organic matter factor, i.e. organic compounds N (%). Soil quality indicators of MDS comprise of bulk density (BD, g cm-3), available water capacity (AWC, %), soil pH, P-available (ppm), soil organic carbon (SOC,%), and water-filled pore space (WFPS,%). Using the equation of SMAF, the SQI of Typic Hapludox was 75, Plinthic Kandiudult was 71, and Plinthic Hapludox was 57. The soil quality did not influence the corn yield (t ha-1).

Kata Kunci : Pengelolaan lahan, mutu tanah