Integrating botanical diversity and management of agricultural grassland

Published source details Geijzendorffer I.R. (2007) Integrating botanical diversity and management of agricultural grassland. PhD thesis. University College Dublin.
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This study is summarised as evidence for the following.

	Action	Category
	Reduce chemical inputs in grassland management Action Link
	Restore/create species-rich, semi-natural grassland Action Link

Reduce chemical inputs in grassland management

A replicated, randomized study of three intensive cattle farms in Ireland over three to five years (Geijzendorffer 2007) found that the number of plant species per field was significantly higher with reduced fertilizer application on only one of three farms, although numbers per quadrat increased with decreased fertilizer application at all sites. At Johnstown Castle, the total number of species per field with no fertilizer application (10 species) was significantly higher than fields with 225 (5-7 species) or 390 kg N/ha (6-8 species). There was no significant difference at Solohead (80 kg N: 5-8 species, 175 kg N: 5-10 species, 225 kg N: 3-8 species, 350 kg N: 6-9 species) or Grange (88 kg N: 10-13 species, 225 kg N: 8-15 species). However, the average number of species per quadrat decreased with increasing levels of fertilizer (e.g. Johnstown Castle: 0 kg N: 4 species, 390 kg N: 3 species; Solohead: 80 kg N: 3 species, 350 kg N: 2 species; Grange: 88 kg N: 4 species, 225 kg N: 3 species). Fertilizer treatments were applied in a randomized block design with two to five replicates per treatment. Vegetation was sampled in 50 quadrats (3 dm³) in each field, three to five years after the treatments commenced.
Restore/create species-rich, semi-natural grassland

A replicated, randomized study of sown grassland species on an intensive cattle farm in Ireland (Geijzendorffer 2007) found that for individual species, the maximum growth rate was either higher at a fertilization rate of 225 kg nitrogen/ha than at 90 kg N/ha, or did not differ. On dry soils, species either experienced slightly more competition with members of the same species at 90 kg N/ha than at 225 kg N/ha, or there was no difference between treatments. Twelve plant species were sown in mixtures of one, two or three species in equal amounts, comprising one species plus perennial rye grass Lolium perenne plus a production/weed grass or legume. Sowing was in April 2004 at a rate of 1.5 or 3 g/m² in plots of 1.5 x 1.5 m at a dry and wet site. High (225 kg N/ha) or low (90 kg N/ha) fertilization rates were applied with three replicates for each seed mixture and soil type in a randomized block design. Biomass was recorded weekly for four to five weeks following cuts in alternate months. Botanical composition and weekly changes in green plant area and relative growth rates were also recorded.