Submitted to: Biology and Fertility of Soils
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/1999
Publication Date: 11/1/2000
Citation: Cochran, V.L., Pugin, J.A., Sparrow, S.D. 2000. Effects of migratory geese on nitrogen availability and primary productivity in subarctic barley fields. Biology and Fertility of Soils. 32(4): 340-346. Interpretive Summary: Migratory geese affect agricultural production by removing biomass and by depositing fecal nutrients. This study used 15N as a tracer to examine the quantitative effects of goose fecal nitrogen contributions on agricultural production. Barley (Hordeum vulgare cv Datal ) was grown for production of 15N-labeled grain and straw. Two Canada geese (Branta canadensis taverners) were fed the grain after harvest to obtain 15N labeled and unlabeled feces. Net nitrogen mineralization and micro-plot studies both indicated that in comparison to barley grain and straw, goose feces provided the greatest amount of available nitrogen to the soil and to subsequent crop, and consequently higher barley yields (59 and 62% increase, respectively). However, carbon mineralization was greater from grain with 56 % evolved compared to 49 and 26 % for feces and straw, respectively. Goose feces also provided the greatest addition of N for the barley plants, with fertilizer nitrogen recovery efficiency (FNRE) of 16%, compared to FNRE of 10% from the grain amendment, and 1.2% from the straw amendment. The amount of N available in fecal material from leftover grain consumed by grazing geese is 3 to 6 kg ha-1. This is small compared to total crop needs, but it is a potential source of mineral N during the critical early growth of crops grown in cool, high latitude soils.
Technical Abstract: Geese migrating out of Alaska in the fall feed on barley grain left in the fields after harvest. This grain is an important energy source for their long flight south. Geese consuming this leftover grain have two potential benefits to the producer. The first is to reduce the amount of volunteer barley in next year's crop; thus, reducing the need for weed control. The other benefit is to increase the availability of the nitrogen in the left over grain. Fertilizer nitrogen is often positionally unavailable because of limited precipitation during crop emergence. Grazing by geese has the potential to increase the availability of soil N by 3 to 6 pounds per acre. This is small in comparison to total crop needs, but it is available at a critical time for use by emerging crops.