Contribution of slope on physical properties of Inceptisols under cassava (<i>Manihot utilissma</i> L) cultivation in Koto Tangah Lima Puluh Kota Regency

Abstract Cassava is a cash crop planted as monoculture in Lima Puluh Kota Regency. The objective of this research was to identify physical properties of Inceptisol at four slope levels under cassava ( Manihot Utilisma ) plantation in Nagari Koto Tangah Lima Puluh Kota Regency. Soil was sampled by purposive sampling at four different slope levels (0-8%, 8- 15%, 15-25%, and 25-45%) at 0-30 cm soil depth. Parameters analyzed were soil texture, organic matter (SOM) bulk density (BD), total soil pores (TSP), hydraulic conductivity (HC), and aggregate stability (AS). The result showed that the soil had clay to clay loam texture. The clay particles tended to increase by increasing slope level since the steepest slope was found at the lower position. Increasing slope levels from 0-8% to &gt;45%, it showed an increase in soil BD (0.78 to 1.07 Mg m −3 ), decrease in TSP (81.46 to 62.97%), SOM (5.43 to 1.05%), HC (18.26 to 3.87 cm h −1 ), and AS (46.19 to 37.13%). It was concluded that the soil physical properties under cassava plantation in Koto Tangah declined by increasing slope level. Compared to pine forest and other dry land farming next to the site, soil physical properties under cassava plantation was still the best.