Production ability of clover-grass mixtures on heavy soils of the East Slovakian Lowland under irrigation conditions

abonos nitrogenados application rates azote clay soils cultivo mixto dose d'application dose d'irrigation dosis de riego essai feed grasses foin hay heno irrigation rates lolium perenne mixed cropping nitrogen nitrogen fertilizers pruebas rendement rendimiento riego complementario sol argileux suelo arcilloso supplemental irrigation trials trifolium repens yields