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A four-year trial was established in Truro, Nova Scotia on the ploughed pasture in 2002 to identify the optimal combinations of organic amendments and crop rotations varying in proportions of forages.
A 3×3 factorial within three blocks included two factors of forages and organic amendments. The first factor forage levels (0, 1, and 2 year's forages in a 4-year crop rotation) were represented by three different 4-year crop rotations: wheat(w)/soybean(b)/barley (b)/potato (p), w/b/forage (f)/p, and w/f/f/p, respectively. For rotations including forages, the timothy and red clover were underseeded in the cereal of the previous year. For the second factor, organic amendments were alfalfa meal, monogastric compost from poultry manure, and ruminant compost from beef cattle and/or sheep manure. The nutrient application rates were based on soil test recommendations. We assumed N availabilities were 30% for alfalfa meal, 25% for ruminant compost, and 50% for monogastric compost in the application year, respectively. For all amendments, 20% of total P was assumed to be available and 90% of total K.
In underseeded plots where forages were seeded in the previous crop,
the nitrogen application rate was reduced by 50%. In 2003 there was no
organic amendment application. The organic amendments had no significant
effects (p=0.05) on N, P, or K uptake during the first two years of rotations.
However, total N and P uptake were significantly (p=0.05) higher in a
0-year forage crop rotation, total K uptake were significantly (p=0.05)
higher in a 2-year crop rotation. There was significantly amendment by
forage interactions on total K uptake.
© 2012, Organic Agriculture Centre of Canada (OACC)