Non-Peer ReviewedIn two field experiments conducted in 1978-79, fall application of incorporated urea, or banded aqua ammonia, produced much less increase in yield and N-uptake than did spring application for barley grain. However, when the fall-applied fertilizers were placed in constricted nests (one nest per each 45 x 45 cm area) the yield and N-uptake were nearly as great as with spring application. The mechanism by which nests avert losses from fall-applied N is through slowing of nitrification, and possibly through lessening of immobilization of fertilizer N by straw. Indirect evidence suggests that placement in nests is more effective than inhibitors of nitrification in reducing losses from fall-applied N fertilizers. The two field experiments in 1978-79, and three experiments in 1977-78 with fall-applied . urea showed that band placement improved yield in comparison to incorporation, but the banding was inferior to nesting. More specifically, yields with incorporation, banding, nesting, and spring incorporation were 960, 1240, 1560, and 1830 kg/ha, respectively. In the same order, values for % uptake of fertilizer N, were 31, 38, 53, and 66 %. Taking all of the eight experiments which have been conducted with nesting during the past four years, average yield increases were 1030, 1750, and 1980 kg/ha for fall incorporation, fall nesting, and spring incorporation,
respectively. This work has been restricted to northern Alberta and northern Saskatchewan, and the feasibility of practical field-scale techniques of nesting, or application of large pellets, has not yet been investigated, but nevertheless the benefit of fall nesting is large enough to suggest work on this topic by
other researchers in other areas of the prairie provinces
