Effects of extensification programmes in agriculture on segetal vegetation

Published source details Hilbig W. (1997) Auswirkungen von Extensivierungsprogrammen im Ackerbau auf die Segetalvegetation. Tuexenia, 17, 295-325.
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This study is summarised as evidence for the following.

	Action	Category
	Increase crop diversity Action Link
	Provide or retain set-aside areas in farmland Action Link
	Reduce fertilizer, pesticide or herbicide use generally Action Link

Increase crop diversity

A replicated, controlled study in summer 1991-1994 in the Province of Bayern, Germany (Hilbig 1997) found that farms in the Bavarian Cultural Landscape Programme (Bayerisches Kulturlandschaftsprogramm), an extensification programme, had more plant species than control farms (15.6 vs 13.8 plant species). There are no restrictions on fertilizer or pesticide use but some less common crops (e.g. flax and grass seeds) can be included in the crop rotation in this extensification programme. The study did not measure the actual number of crops in rotation on these farms. Vegetation was surveyed between June and September on total areas between 100 and 400 m². Cereal crops were surveyed yearly, cut set-asides several times a year. Note that no statistical analyses were performed on the data.
Provide or retain set-aside areas in farmland

A replicated, controlled study in summer 1991-94 on three to six arable farms and two experimental sites in the Province of Bayern, Germany (Hilbig 1997) found more plant species on rotational set-asides (17.4 species) than on control fields (10.8 species). Moreover, naturally regenerated set-asides held more plant species (range 18.3 to 32.2 spp.) than set-asides with sown clover-grass mixtures (range 16.0 to 18.9 spp.). This effect was still visible the following year, when cereal was grown on the former set-aside fields (range 13.3 to 14.2 spp. on cereal after natural regenerated set-aside vs 12.0 to 12.4 spp. on cereal after sown set-aside). Rotational set-asides were taken out of production for one year and either left to regenerate naturally or sown with a clover-grass-mix. Controls were often cereal fields. Vegetation was surveyed between June and September on total areas between 100 and 400 m². Cereal crops were surveyed yearly, cut set-asides several times a year. Note that no statistical analyses were performed on these data.
Reduce fertilizer, pesticide or herbicide use generally

A replicated, controlled study in summer 1991-1994 on up to 13 farms and two experimental sites in the Province of Bayern, Germany (Hilbig 1997) found that the two management types with restricted pesticide use (organic farming and controlled contract production, ‘KVA’) had a more positive effect on plant species richness (average ranges for the sites: organic: 18.4-22.6 species, KVA: 16.9-19.0 spp., controls: 12.4 to 14.6 spp.) than the Bavarian culture landscape programme or control farms (15.6 and 13.8 spp. respectively). Farms under organic or controlled contract production both had restrictions concerning pesticide use. In the Bavarian culture landscape programme, no such restrictions existed but some less common crops (e.g. flax and grass seeds) can be included in the crop rotation. Vegetation was surveyed between June and September on total areas between 100 and 400 m². Cereal crops were surveyed yearly, cut set-asides several times a year. Note that no statistical analyses were performed on these data.