Experiments were carried out in the Vėžaičiai Branch of the Lithuanian Institute of Agriculture (West Lithuania region) in 2002-2005. The aim of this research was to estimate the ecological significance of perennial legumes used as green manure for the biological properties of triticale and rye and for diseases resistance. Residues of the perennial grasses tested and ploughed-in aftermath contributed different contents of nitrogen to the soil. The highest content of nitrogen was contributed to the soil with red clover residues and aftermath. Residues of white clover and aftermath ploughed in as green manure determined more favourable soil properties. This had a positive effect on the formation of biological parameters of cereals grown after white clover, which made it possible without mineral and organic fertilisers to produce on average 3.88 t ha-1 of triticale grain and 3.82 t ha-1 of rye grain, or by 1.09 and 0.28 t ha-1 more compared with their growing after red clover managed in the same way as white clover. Different growing conditions of winter cereals, i.e. different preceding crops, had a significant effect on the occurrence of scald and septoriosis. Poskusi so bili opravljeni v Vėžaičiai Branch na Lithuanian Institute of Agriculture v obdobju od leta 2002 do 2005. Namen raziskave je bil oceniti ekološki pomen trajnih metuljnic, uporabljenih za zeleno gnojenje, na odpornost proti boleznim ter na biološke lastnosti tritikale in rži. Zaorani ostanki zelenih delov preizkušanih metuljnic so imeli različne vplive na vsebnost dušika v tleh. K najvišji vsebnosti dušika so prispevali ostanki rdeče detelje, zaorani ostanki bele detelje pa so imeli ugodnejše učinke na lastnosti tal. Izboljšane talne lastnosti so pozitivno vplivale na parametre rasti, ki so omogočili pridelek 3,88 t ha-1 zrnja tritikale in 3,82 t ha-1 zrnja rži brez uporabe mineralnih ali drugih organskih gnojil. Ko je bil predhodni posevek rdeča detelja, je bil pridelek tritikale manjši za 1,09 t ha-1, pridelek rži pa za 0,28 t ha-1 manjši v primerjavi s pridelkom po zelenem gnojenju z belo deteljo. Različni predhodni posevki so imeli pomemben vpliv na pojavnost ožiga in listne pegavosti.