Yield and quality of mixed seed crops of timothy (Phleum pratense) and clovers (Trifolium spp.) in an organic cropping system

摘要

Seed production of timothy (Phleum pratense L.) in mixed crops with alsike (Trifolium hybridum L.), white (T. repens L.) or red (T. pratense L.) clover was evaluated in an organic cash crop system. No fertilizer was applied except for household compost in the sowing year. While the first year crops of the alsike clover/timothy and red clover/timothy leys were harvested for clover seed, the first year crop of the white clover/timothy ley and all second year crops were harvested for timothy seed. The botanical composition of the alsike clover/timothy crop averaged 89/11 in the first ley year, and 8/92 in the second year. The corresponding yields averaged 443 kg ha(-1) clover seed and 849 kg ha(-1) timothy seed, respectively. Second year seed yields of timothy from mixtures with red and white clover were, in turn, 7% higher and 44% lower than from the corresponding mixture with alsike clover. First year seed yields of alsike clover from the alsike clover/timothy combination, and first year yields of timothy from the timothy/white clover combination were mostly rejected because of insufficient purity. In contrast, first year seed yields of red clover from the red clover/timothy combination, and second year yields of timothy from all combinations, never failed to met the international requirement of maximum 1% contamination of one particular species in certified seed.