Individual study: Seeding Rate and Planting Arrangement Effects on Growth and Weed Suppression of a Legume-Oat Cover Crop for Organic Vegetable Systems
Brennan E.B., Boyd N.S., Smith R.F. & Foster P. (2009) Seeding Rate and Planting Arrangement Effects on Growth and Weed Suppression of a Legume-Oat Cover Crop for Organic Vegetable Systems. Agronomy Journal, 101, 979-988
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Pest regulation: Grow cover crops in arable fields
A replicated, randomized, controlled study in 2003–2005 in two irrigated fields in the Salinas and Hollister Valleys, California, USA (partly the same study as (11)), found fewer weeds in plots that were sown with more cover crop seeds, compared to fewer. Implementation options: Fewer weeds were found in plots that were sown with more cover crop seeds, compared to fewer, in seven of 12 comparisons (336 kg seeds/ha: 0–2% of dry matter was weeds; 112 kg seeds/ha: 0–10%). Similar numbers of weeds were found in plots that were sown in a grid (two passes of the seed drill, in perpendicular rows, with half as many seeds/pass as conventional passes), compared to conventionally (one pass, in parallel rows) (data not reported). Methods: In Hollister, there were twenty-four 12 x 12 m plots. Half were sown in a grid, and half were sown conventionally. In Salinas, there were nine 12 x 15 m plots. All plots were sown with cover crops in November 2003–2004 (112, 224, or 336 kg seeds/ha). The seeds were a mixture of oats and legumes (beans, peas, and vetch). Biomass was measured four times/year in December–April 2004–2005 (one quadrat/plot, 100 x 50 or 50 x 50 cm).