[Sulfur levels of grassland plots show great variations within farms]

analyse de sol azote azufre carence en substance nutritive chemical composition clay soils composition chimique crops cultivos deficiencias nutritivas grasslands herbage loess loess soils netherlands nitrogen nutrient balance nutrient deficiencies plante de culture praderas riesgo risk risque sandy soils soil testing soil types sol argileux sol de loess sol sableux soufre suelo arcilloso suelo arenoso sulphur tipos de suelos type de sol