ABSTRACT
Summary In four regions of Poland experiments begun in 1973 and planned to last 12 years compared cutting and grazing yields of permanent grasslands over 20-30 years old to yields of seven field fodder-production models. The models had 3-, 4- and 6-year rotations. The experiments were located on mineral soils with 28%-50% silt and clay and 2.1%-3.5% humus. The water table depth varied from 44 to 170 cm in spring and from 115 to more than 175 cm in summer. Average precipitation was 375-515 mm during the growing season (April-October) and 523-658 mm annually. Average annual fertilization/ha was as follows: N, 360 kg; P2O5, 150 kg; and K2O, 280 kg. Experiments used the randomized-block method with 4 replications of 36 m2 plots (82 m2 gross). Results after 8 years showed that the average annual yields of green matter were 54-75 t/ha (t = 1000 kg); fodder beet roots, 116-135 t/ha; potatoes, 30-39 t/ha; and broad bean seeds, 3.1-3.5 t/ha. Calculated in comparable units, the yields of digestible protein were higher in pastures and meadows (1.6 t/ha) than in the other models (0.98-1.16 t/ha). Yields of starch from meadows were 7.2 t/ha; from pastures 6.0 t/ha; and from field models 5.8-7.6 t/ha. Starch and protein yields calculated in cereal units were 12.7 t/ha from meadows, 11.2 t/ha from pastures, 11.8 t/ha from the highest-yielding field model, and 9.6-10.8 t/ha from the other field models. These results showed that permanent meadows and pastures lying on mineral soils and under intensive fertilization and exploitation yielded as much as cultivated fields and still maintained a high level of productivity after 8 years of intensive exploitation.
