Weed infestation of cereals and bioindication of selected soil properties in organic and conventional farming systems. Pt. 2. Assessment of selected soil properties in 1999 and 2005 using weeds as bioindicators

agricultura alternativa agricultura tradicional agriculture alternative agriculture traditionnelle alternative agriculture campo cereal crops champ cultivos de cereales cultivos de invierno cultivos de primavera culture d'hiver culture de printemps dominant species especies especies dominantes exploitation agricole explotaciones agrarias farming systems farms fields indicator plants infestation luvisol luvisoles luvisols malezas mauvaise herbe plantas indicadoras plante indicatrice poland pologne polonia soil chemicophysical properties soil types species spring crops statistical methods tipos de suelos traditional farming type de sol variedades varieties weeds winter crops