TY - JOUR T1 - Regional climatological probabilities to increase success and reduce risk in rain-fed cover crop management JF - Journal of Soil and Water Conservation SP - 377 LP - 384 DO - 10.2489/jswc.71.5.377 VL - 71 IS - 5 AU - B.M. Svoma AU - C.J. Gantzer Y1 - 2016/09/01 UR - http://www.jswconline.org/content/71/5/377.abstract N2 - A key component of successful cover crop management is the timely termination of the winter cover crop in spring to prevent reduction of soil moisture through transpiration. For the Great Plains and Midwest, a 33 year daily record of temperature and precipitation is used to develop empirical probabilities of prolonged low soil moisture storage for a surface with a growing cover crop in April. The potential for spring soil moisture loss from a growing cover crop and a subsequent lack of rainfall generally increases from north to south, and especially from east to west, and in time through the month of April. There are exceptions to this pattern as some areas (e.g., Iowa and Nebraska) display decreases in the probabilities of low soil moisture storage events (a week with four or more days of storage less than 10% of available water capacity) through April and in some northern areas (e.g., North Dakota and western Minnesota) precipitation remains relatively infrequent through April, leading to high frequencies of low soil moisture storage events in late April. The probability of low storage events exceeds 0.54 for drier areas with lower water-holding capacity soils especially in the last two weeks of April, while areas with frequent precipitation, cooler temperatures, and higher water-holding capacity soils display much lower probabilities (<0.18) through April. Although precipitation frequency increases substantially through April in Kansas, Nebraska, and South Dakota, timely termination is critical in these areas as well as North Dakota and western Minnesota. In other areas (e.g., the tri-state border of Minnesota, Wisconsin, and Iowa) termination may be delayed, as prolonged low soil water storage is unlikely. While interannual trends in mean and variability were not evident in the observational record used here, it is known that models project drier and more variable future spring conditions, high-lighting the need for information to support timely cover crop termination in spring. ER -