W. Kalk

A method of energy balancing in crop production and its application in a long-term fertilizer trial

K. Hülsbergen, B. Feil, S. Biermann, 2001 .

Management‐related material and energy balances for the rating of production intensity and environmental acceptability of land use

K. Hülsbergen, S. Biermann, W. Kalk, 1998 .

Emission of methane, nitrous oxide, and ammonia from dung windrows

Hans Jürgen Hellebrand, W. Kalk, H. Hellebrand, 2001, Nutrient Cycling in Agroecosystems.