Soil Strength and Water Infiltration Under Reduced and Conventional Tillage in a Typic Haplustepts of Lamongan District

. The ability of upland non-irrigated soil to absorb and store water is critical to to provide sufficient moisture for crop grown in dry season. The objective of this study was to evaluate the effects of tillage, reduced (RT) and conventional tillage (CT), on infiltration rate and soil penetration resistance (soil strength) in soil with ustic moisture regime planted with corn. The experiment was conducted on a site, which had been continuously planted with corn twice a year. The predominant soil was Typic Haplusteps. Six positions, 15 meters a part, were chosen within each treatment to measure infiltration rate and soil strength. The mean infiltration rate values were higher under CT (91.87 ± 18.99 mm h-1) than under RT (64.36 ± 30.97 mm h-1). The amount of water infiltrated in CT is 1.4 times higher than in RT. The RT induced the formation of near surface compacted layer with a soil strength of 850 kPa, 2 times higher than under CT at the same depth. The compacted layer is expected to be responsible for lowering infiltration rate under RT. The highest correlation (R2 = 0.83) between qs and Ksat under RT was found at the second depth (8 to 12-cm) and third depth (16 to 20-cm) for CT (R2 = 0.73) indicating that soil layer with the highest soil strength was responsible to control water infiltration. The infiltration models tested (Parlange, the Green and Ampt, and Kostiakov) fit well with the measured data (r2 = 0.99–1.00). It is recommended to conduct deep tillage (20 – 25 cm) once a year to maintain favorable soil structure for water infiltration and root growth