Soil Aggregate Stability Index on Agricultural, Plantation, and Forest Lands

Abstract

The soil aggregate stability index is one of the critical indicators of soil physical quality, primarily related to the soil's ability to absorb water into the soil and the soil's resistance to rainwater splashing and surface flow erosion in the soil erosion process. The study aimed to determine the soil aggregate stability index class criteria using the dry and wet sieving methods on the OSK 10701 sieve type and to identify the stability of soil aggregates on agricultural land, plantations, and forests around the IPB Dramaga campus. The transformation of the soil aggregate stability class criteria from the conventional sieve to the OSK 10701 sieve types gave excellent results with a coefficient of determination (R2) of 0.89. The soil aggregate stability index differs significantly between soil types and land uses. Podsolic Jasinga has a higher aggregate stability index than Podsolik Dramaga, Regosol Dramaga, and Latosol Dramaga in the upper layer (0-20 cm) and the lower layer (20-40 cm). Forests have a better aggregate stability index than conservation agricultural land, conventional agricultural land, rubber plantations, and oil palm plantations. The difference in stability index between land uses is closely related to soil organic matter contents. Although the soil is denser/more compact, the soil in oil palm and rubber plantations has a lower stability index and is classified as unstable.Indek kestabilan agregat tanah merupakan salah satu indikator kunci kualitas fisik tanah khususnya terkait dengan kemampuan tanah dalam meresapkan air kedalam tanah serta ketahanan tanah terhadap daya percik air hujan dan daya gerus aliran permukaan pada proses erosi tanah. Penelitian ditujukan untuk menentukan kriteria kelas indek kestabilan agregat tanah metoda pengayakan kering dan basah pada tipe ayakan OSK 10701 dan mengidentifikasi kestabilan agregat tanah pada lahan pertanian, kebun dan hutan disekitar kampus IPB Dramaga.  Transformasi kriteria kelas kestabilan agregat tanah dari tipe ayakan konvensional kedalam tipe ayakan OSK 10701 memberikan hasil yang sangat baik dengan koefisien determinasi (R2) 0.89.  Indek kestabilan agregat tanah berbeda nyata antar jenis tanah dan antar penggunaan lahan. Tanah Podsolik Jasinga memiliki kestabilan agregat yang lebih tinggi dibandingkan dengan tanah Podsolik Dramaga, Regosol Dramaga dan Latosol Dramaga baik pada lapisan atas (0-20 cm) maupun lapisan bawah (20-40 cm).  Hutan tanaman mempunyai indek kestabilan agregat yang lebih baik dibandingkan dengan lahan pertanian konservasi, lahan pertanian konvensional, kebun karet dan kebun kelapa sawit.  Perbedaan indeks kestabilan antar penggunaan lahan berkaitan erat dengan kadar bahan organik tanah.  Walaupun tanahnya lebih padat/kompak tanah pada kebun kelapa sawit dan kebun karet mempunyai indek kestabilan yang lebih rendah dan tergolong tidak stabil.