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Herbage from legumes or legume-rich swards potentially has lower concentrations of water soluble carbohydrates (= wsc) and a higher buffering capacity (= bc) than grass grown in pure stands. The analysis of three forage legumes (= Trifolium repens, Tri-folium pratense and Lotus corniculatus) in monoculture and mixtures (= 50/50) with the grass species Festuca rubra demonstrates, that the ratio of wsc concentration to bc is critical low, especially when the herbage is harvested at physiological young stages to obtain a higher forage quality. This means an increased risk for silage mak-ing, especially at DM contents which are below 30%. New breedings of the grass spe-cies Lolium perenne with higher sugar contents offer a possibility to increase the wsc concentration in grass/legume mixtures. Our studies show, that the tested high-sugar grass is suitable to increase the wsc concentrations in mixture. However, the grass has grown in monoculture. A present project is focussed on the open question if the advantage of high-sugar varieties is also evident in legume/grass mixtures.

Humus balances are intended to serve as instruments to support humus management in practice. Still, urgent need for adaptation especially with regard to apllication in organic farming has been stated. Results presented in this paper show that there in fact is a difference in humus repro-duction between conventional and organic farming that is not recognized in balance methods. In addition, the results exhibit a big uncertainty in balance results. They are pointing out basic problems of humus balance methods that are likely to be caused by an insufficient consideration of site-specific factors of the humus household and their interaction with farming.