Efecto de la fertilización nitrogenada y fosfórica sobre el estado de desarrollo de gramíneas de prados en la montaña de León

Laburpena

Growth stages of 11 grasses of 14 meadows (Order Arrhenatheretalia) located in the Area ofRiaño (Mountain of León, Cantabrian Mountains) were studied. For 10 years, meadows have beenfertilized with two levels of N (low level: <60 kg ha-1year-1; and high level: >60 kg ha-1year-1) and P2O5(low level: <80 kg ha-1year-1; and high level: >80 kg ha-1year-1). Samples were taken at three differentearly harvest dates, each of them related to a possible management of forage resources: zero grazing,conservation through early silage and conservation through late silage. Phenological stage of eachspecies was described through the data from 5-25 stems. Fertilization had little effect on growth stageat early harvest dates; six species: Alopecurus pratensis, Anthoxanthum odoratum, Cynosurus cristatus, Holcuslanatus, Lolium perenne and Poa pratensis showed a more marked relationship between fertilization andphenological stage. Both nitrogen and phosphorus fertilization had a positive effect on C. cristatusgrowth at zero grazing harvest time: boot stage was reached with high level of fertilization whereasthat with low level of fertilization only stem elongation was reached. Fertilization had the opposite effect on A.odoratum at early silage time, which reached a more developed growth stage (anthesis) witha low level of fertilization than with a high level of fertilization (preanthesis – peduncle fully elongated).