Changes in continuous timothy production with time in a long-term dykeland experiment

Abstract

The effects of 64 yr of various fertility strategies upon forage DM yield, botanical composition, and persistence of timothy (Phleum pratense L.) were evaluated on dykeland fields (Acadia soil) under a continuous (without plowing) hay production system. Fertility treatments during the first 41 yr of this study were: (1) no fertilizer, (2) 18 t manure ha−1 every 4 yr, and (3) 36 kg ha−1 of N and 11 kg ha−1 of P applied annually. The experiment was modified in the 42nd year by increasing the rate of nutrient application to 45 t manure ha−1 every 2 yr, and 153 kg ha−1 of N plus 25 kg ha−1 of P applied annually with one of four levels of K (0, 56, 169 and 282 kg ha−1). The application of manure and commercial mineral fertilizer substantially increased yield over no fertilizer. Evidence of beneficial long-term effects was observed in the manure fertility treatment, while there appears to have been a gradual yield decline associated with commercial mineral fertilizers. Soil and foliar analyses suggest that the depletion of other nutrients not applied in this study and the decreased nutrient availability induced by lowering pH could be responsible for the observed yield decline. The application of potassium did not affect DM yield or the long-term persistence of timothy in this study. The application of manure and mineral fertilizers enhanced the long-term persistence of timothy. Key words: Dykeland, manure, N, P, K, fertilization, yield, persistence, timothy