Herbage, Phosphorus, and Nitrogen Yields of Winter‐Season Forages on High‐Phosphorus Soil

In climates where cool seasons can produce a forage crop, annual grasses and forbs can be used on dairies to recycle nutrients back to the animals and to phytoremediate soils high in P or N. In north‐central Texas, on a Windthorst fine sandy loam (fine, mixed, thermic, Udic Paleustalf) with 250 mg P kg −1 , an on‐dairy trial measured yields of dry matter (DM), N, and P, as well as fiber fractions of five cool season legumes, six grasses, and two brassicas. Some grasses yielded >8 Mg herbage DM during high rainfall years, whereas the most productive legumes and brassicas could only match half that production. Because the soils were high in nitrate‐N and plant‐available P, concentrations of these were high in herbage, resulting in >150 kg N ha −1 yield in seven of the entries and >20 kg P in eight entries during a high‐rainfall year. Potential for extracting, fixing, and sequestering N and P, combined with generally low fiber concentrations, indicated that some of these forages hold promise for nutrient recycling or phytoremediation of high‐N or ‐P dairy soils with the added benefit of producing nutritious forage for the dairies.