land Article Infiltration-Friendly Agroforestry Land Uses on Volcanic Slopes in the Rejoso Watershed, East Java, Indonesia Didik Suprayogo 1,*, Meine van Noordwijk 1,2,3 , Kurniatun Hairiah 1, Nabilla Meilasari 1, Abdul Lathif Rabbani 1, Rizki Maulana Ishaq 1 and Widianto Widianto 1 1 Soil Science Department, Faculty of Agriculture, Brawijaya University, Jl. Veteran no 1, Malang 65145, Indonesia;
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[email protected] Received: 9 June 2020; Accepted: 14 July 2020; Published: 23 July 2020 Abstract: Forest conversion to agriculture can induce the loss of hydrologic functions linked to infiltration. Infiltration-friendly agroforestry land uses minimize this loss. Our assessment of forest-derived land uses in the Rejoso Watershed on the slopes of the Bromo volcano in East Java (Indonesia) focused on two zones, upstream (above 800 m a.s.l.; Andisols) and midstream (400–800 m a.s.l.; Inceptisols) of the Rejoso River, feeding aquifers that support lowland rice areas and drinking water supply to nearby cities. We quantified throughfall, infiltration, and erosion in three replications 1 per land use category, with 6–13% of rainfall with intensities of 51–100 mm day− . Throughfall varied from 65 to 100%, with a zone-dependent intercept but common 3% increase in canopy retention per 10% increase in canopy cover.