Cool‐season lawn performance as influenced by ‘Microclover’ inclusion and supplemental nitrogen

Lawns require a steady supply of nitrogen (N) to maintain green color and seasonal shoot density. Excess N fertilization can lead to surface and groundwater contamination, suggesting a need for alternative turf fertilization strategies that reduce the reliance on frequent N applications. Grass‐legume mixtures may be one solution since legumes, like white clover ( Trifolium repens L.), biologically fix atmospheric N and add it to the soil via mineralization. This field study evaluated the growth, appearance and persistence of a cool‐season grass and grass‐legume mixture containing a low growing Trifolium repens , ‘Microclover’ (MC) with and without supplemental N fertilization (0 vs. 98 kg N ha −1 yr −1 ) over two growing seasons. Turf with MC and receiving supplemental N produced the most dry matter yield (DMY) 15583 kg ha −1 and the highest mean visual appearance. By contrast, unfertilized turf without MC produced the least DMY, 3815 kg ha −1 , and the poorest appearance, which lacked vigor and was negatively affected by leaf blighting diseases. The unfertilized turf with MC produced moderate growth, 8754 kg ha −1 , with an acceptable appearance. Clover populations decreased over time in both the unfertilized and fertilized grass‐legume mixtures but less so where supplemental N was not applied. This decline in clover could possibly be remedied by periodic overseeding. In summary, these results suggest that a cool‐season grass‐clover lawn mixture can provide a persistent and visually acceptable lawn that would require less reliance on supplemental N fertilization.