Spatial Modeling of Critical Planting Date for Winter Rye Cover Crop to Enhance Nutrient Recovery

Time of planting plays a critical role in nutrient recovery from soils by a winter rye (Secale cereale L.) cover crop. A delay in planting can significantly decrease cover crop performance. This study evaluated cover crop planting dates for different areas of Massachusetts using a spatial model based on growing degree days. Field studies were conducted during 2004 through 2009 to estimate biomass production and nutrient recovery of rye under various planting dates from mid-August to early October. A spatial model identified the critical planting date (CPD) for all locations in Massachusetts based on field studies combined with long-term weather data collected from 14 weather stations. In eastern areas of Massachusetts (Zone 5), CPD is the third week of September. In this region, there is adequate time for planting winter rye aft er corn (Zea mays L.) is harvested. Critical planting dates for central parts of the state (Zones 3 and 4) are from the first to second weeks of September. Growers in these regions should consider alternative management strategies including selection of shorter season corn hybrids to meet the suggested cover crop planting dates. The suggested critical planting dates (third-fourth week of August) for northwest regions of Massachusetts (Zones 1 and 2) may not be practical because corn silage is usually not ready for harvest until mid-September. The model can be a powerful decision-making tool for researchers and farmers, not only for winter rye in Massachusetts, but it also can be adapted for use with other cover crop species and for use in other regions where cover crops are grown.