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Bryan, 1974; Niehaus, 1976;Hsiang et al., 1997;Larsen et al., 2004a). Larsen et al. (2004a) found that the time Temperature is among the most influential environmental factors factor was important for the establishment of Kentucky for germination and establishment of grass species. We compared germination response to suboptimal temperature for the turfgrass bluegrass in mixtures. When this species was given a species slender creeping red fescue (Festuca rubra L. var. littoralis time advantage by sowing it up to 35 d earlier than Vasey), perennial ryegrass (Lolium perenne L.), and Kentucky bluered fescue and perennial ryegrass, the established turf grass (Poa pratensis L.). Two cultivars of each species were germiconsisted of a considerably larger proportion of Kennated at five constant temperatures (8, 12, 16, 20, and 24؇C), and tucky bluegrass tillers. Slow establishment of Kentucky germination was recorded one to three times per day. Final germinabluegrass may, however, be due to both slower emertion percentage was little affected by temperature, indicating that the gence (Pommer, 1972; Bø, 1989) and/or slower seedling base temperature for germination (T b ) is relatively constant within growth (Arnott and Jones, 1970; Henderlong, 1971) seed populations. Consequently, germination response to temperature compared to red fescue and particularly perennial ryewas analyzed by a nonlinear regression method, which combined the grass. To get a better understanding of the poor estabthermal time model and the four parameter Weibull function. The analysis provided biologically significant parameters for comparing lishment of Kentucky bluegrass in species mixtures, it the cultivars and species. T b only varied slightly between species, from is relevant to distinguish between species differences in 2.6؇C for red fescue and Kentucky bluegrass to 3.6؇C for perennial germination rate, pre-emergence seedling growth rate, ryegrass. Thermal time to 50% of final germination was 63.9 degreeand post-emergence seedling growth rate. In particular, days for perennial ryegrass, 43.8 for red fescue, and 115.6 for Kentucky it is relevant to study how the different grass species bluegrass, and thermal time from 25 to 75% of final germination was respond in these aspects to various environmental fac-14.9, 11.1, and 35.0 degree-days. Thus, Kentucky bluegrass requires tors. Along with water potential, temperature is one of a longer thermal time to germinate and has a larger variation in the most important factors for seed germination (Bewthermal time requirement within a seed lot. Consequently, low soil ley and Black, 1994). However, there appears to be no temperature results in a relatively slower germination of Kentucky published results that compare the germination response bluegrass, possibly resulting in a poorer competitive ability of this species. This suggests that poor establishment of Kentucky bluegrassto temperature of the grass species red fescue, perennial may partly be due to a larger thermal time required for germination. ryeg...

Production of energy crops is promoted as a means to mitigate global warming by decreasing dependency on fossil energy. However, agricultural production of bioenergy can have various environmental effects depending on the crop and production system. In a field trial initiated in 2008, nitrate concentration in soil water was measured below winter wheat, grass-clover and willow during three growing seasons. Crop water balances were modelled to estimate the amount of nitrate leached per hectare. In addition, dry matter yields and nitrogen (N) yields were measured, and N balances and energy balances were calculated. In willow, nitrate concentrations were up to approximately 20 mg l À1 nitrate-N during the establishment year, but declined subsequently to <5 mg l À1 nitrate-N, resulting in an annual N leaching loss of 18, 3 and 0.3 kg ha À1 yr À1 N in the first 3 years after planting. A similar trend was observed in grass-clover where concentrations stabilized at 2-4 mg l À1 nitrate-N from the beginning of the second growing season, corresponding to leaching of approximately 5 kg ha À1 yr À1 N. In winter wheat, an annual N leaching loss of 36-68 kg ha À1 yr À1 was observed. For comparison, nitrate leaching was also measured in an old willow crop established in 1996 from which N leaching ranged from 6 to 27 kg ha À1 yr À1. Dry matter yields ranged between 5.9 and 14.8 Mg yr À1 with lowest yield in the newly established willow and the highest yield harvested in grass-clover. Grass-clover gave the highest net energy yield of 244 GJ ha À1 yr À1 , whereas old willow, winter wheat and first rotation willow gave net energy yields of 235, 180 and 105 GJ ha À1 yr À1 . The study showed that perennial crops can provide high energy yields and significantly reduce N losses compared to annual crops.

Management of turfgrass on football pitches without pesticides involves a considerable challenge for weed control. By improving conditions for grass growth by cultural practices, weeds may be repressed by stronger competition from the grass. A 3-year field trial on 37 football pitches investigated the effects of various cultural management practices on percentage grass, weed and bare ground, respectively. The trial included twelve different treatments, comprising different combinations of fertiliser level and cultural methods, including two types of spring-tine harrow, vertical cutting, over-seeding, and top-dressing. Some treatments resulted in significant differences in percentage grass and weed cover, but not in percentage bare ground. However, other factors, such as locality of the football pitch, zone on the pitch, month, year, playing frequency, cutting frequency and, particularly, ground cover at the beginning of the trial, also contributed considerably to the variation in ground cover, indicating that established weeds are difficult to eradicate.