Double Cropping for Forage Crop: How Much Soil Water is Needed to Sow?
August 9, 2012
Forage is scarce and values are high. Crop maturity will be early this summer and fall with expectation of early harvests. Some failed corn and soybeans have been or will be cut for forage. This may create an opportunity for planting a cool season forage crop to be grazed or harvested for hay.
Soil water has been very much depleted in rainfed fields. Water in the surface soil is well below the permanent wilting point. Sowing after a rainfall that does not adequately restore soil water will have a high risk of failed crop establishment.
Under rainfed conditions we suggest that sowing of forage crops be delayed under rainfed conditions until at least two inches of rainfall are received within a one-week period or, for medium and fine texture soils, that precipitation has wetted the soil to at least the 8-inch depth. Wetting should be deeper for sandy soils. A successful crop will still require additional rainfall as the crop will need 4-5 inches of water for each ton of dry weight production, but this sowing guideline gives a good probability of successful crop establishment.
Extension Soils Nutrient Management Specialist
Extension Forage Specialist