Infiltration Rate as Affected by an Alfalfa and No-till Cotton Cropping System

Previous studies measured a long-term increase in infiltration rate in a sandy loam soil with time when alfalfa (Medicago sativa L., cv. WL514) was grown. Cotton (Gossypium hirsutum L.) was direct- planted into alfalfa to determine if the high infiltration rates meas- ured under alfalfa culture could be maintained in cotton under either a till or no-till system. Treatments were no-till or tillage to the 0.15- m depth just before the cotton was planted. Prior compaction levels created by harvest traffic applied to the alfalfa made the soil loose or compacted. Cotton was planted flat and irrigated as a basin. In- filtration rates measured 2 h after water was applied and averaged for the season were 101 (no-till, loose), 56 (till, loose), 82 (no-till, compacted), and 42 mm/h (till, compacted). All the infiltration rates were much higher than normally measured for cotton in these soils. Water flow in the 5-yr-old alfalfa was determined to be mainly through the soil macropore system. High infiltration rates measured in the no-till cotton were also probably the result of flow through the macropores.