[Long term trials with reduced tillage]

amendement du sol application date aradura avena brassica clay soils conservation tillage crop residues crop yield date d'application enmiendas del suelo harrowing hersage hordeum labour loam soils noruega norway paille paja papa ploughing pomme de terre potatoes rastreo rendement des cultures rendimiento de cultivos residuos de cosechas soil amendments sol argileux sol sablolimoneux straw suelo arcilloso suelo franco travail du sol de conservation triticum