Pemetaan Spasial Air Tersedia dan Simpanan Karbon Tanah Berdasarkan Variasi Posisi Lereng di Candibinangun, Pakem, Sleman

Farid Setiawan Suryadi, Riska Ayu Purnamasari, S.Si., M.Agr.Sc., Ph.D.; Andi Syahid Muttaqin, S.Si., M.Si., Ph.D.; Tantriani, S.P., M.Agr., Ph.D.

2026 | Skripsi | ILMU TANAH

Tanah bersifat kontinu dan menunjukkan variasi karakteristik secara horizontal maupun vertikal akibat perbedaan faktor pembentuk tanah dan proses pedogenesis. Variasi tersebut tercermin pada kemampuan tanah dalam menyimpan air tersedia dan mengakumulasi karbon, namun informasi distribusi spasial kedua parameter tersebut di Kalurahan Candibinangun masih terbatas. Penelitian ini bertujuan menganalisis pola perubahan karakteristik tanah berdasarkan posisi lereng dan kedalaman, serta memetakan distribusi spasial air tersedia dan simpanan karbon tanah. Penelitian menggunakan metode Stratified Purposive Sampling pada tiga strata posisi lereng (atas, tengah, bawah) dan tiga kedalaman (0-20, 20-40, 40-60 cm). Data dianalisis menggunakan Two-Way ANOVA, korelasi Spearman, serta interpolasi spasial Ordinary Co-Kriging dengan data DEMNAS sebagai kovariat. Hasil penelitian menunjukkan tanah didominasi tekstur geluh pasiran dengan KPK dan C-organik tergolong rendah. Kedalaman tanah berpengaruh signifikan terhadap C-organik, simpanan karbon, dan berat volume, di mana ketiganya menurun seiring bertambahnya kedalaman kecuali berat volume yang meningkat. Air tersedia tidak menunjukkan perbedaan nyata antar posisi lereng maupun kedalaman, namun lapisan top soil memiliki nilai air tersedia yang lebih rendah dibanding lapisan bawah. Simpanan karbon menunjukkan hubungan sangat kuat dengan C-organik (r=0,93) dan terkonsentrasi pada lereng atas serta lapisan top soil, dengan nilai tertinggi mencapai 110 ton/ha. Hasil ini menunjukkan bahwa kandungan bahan organik merupakan faktor utama yang mengendalikan distribusi simpanan karbon sehingga pengelolaan bahan organik dan irigasi menjadi penting untuk mendukung keberlanjutan lahan di wilayah penelitian.

Soil is a continuous natural body that exhibits both horizontal and vertical variation due to differences in soil-forming factors and pedogenic processes. This variation is reflected in the soil's capacity to retain available water and accumulate carbon, yet spatial information on both parameters in Candibinangun remains limited. This study aimed to analyze patterns of soil characteristic change across slope and depth gradients, and to map the spatial distribution of soil available water and carbon stock. A Stratified Purposive Sampling method was applied across three slope strata (upper, middle, lower) and three depth (0-20, 20-40, 40-60 cm). Data were analyzed using Two-Way ANOVA, Spearman correlation, and Ordinary Co-Kriging spatial interpolation with DEMNAS data as a covariate. The result showed that soil was dominated by sandy loam texture with low cation exchange capacity and organic carbon content. Soil depth significantly affected organic carbon, carbon stock, and bulk density, where the first two decreased with increasing depth while bulk density increased. Available water did not differ significantly across slope or depth, although the topsoil layer showed lower available water value than deeper layers. Carbon stock showed a very strong correlation with organic carbon (r=0.93) and was concentrated at higher slopes and in the topsoil layer, reaching maximum value of 110 tons/ha. These findings indicate that organic matter content is the dominant factor controlling carbon stock distribution, highlighting the importance of organic matter and irrigation management to support sustainable land use in the study area.

Kata Kunci : air tersedia, co-kriging, karakteristik tanah, simpanan karbon, spasial