A combination of dairy manure and commercial fertilizer brought higher grass yields than either nutrient source alone in a Cornell University study.

Fields of orchardgrass, tall fescue and reed canarygrass received nitrogen fertilizer at spring green-up, or half the total amount then and after the first cutting. In another treatment, a third of the total was applied in spring and after the first two cuttings. Those treatments were compared with two manure applications or three applications of manure plus fertilizer.

Compared to a single N application, split applications increased grass yield about 5%, and three-way splits brought an 8% gain, say the researchers. Ma-nure application resulted in 20% lower yield than commercial N, while a combination of manure and fertilizer beat fertilizer alone by 10%.