• Effect of Different Herbicides on Various Legume Crops in Interior Alaska

      Sparrow, Stephen D.; Conn, Jeffrey S. (Agricultural and Forestry Experiment Station, School of Agriculture and Land Resources Management, University of Alaska Fairbanks, 1992-09)
      One of the major problems in the production of successful forage/green manure legume crops in Alaska is weed control. Many species of legumes are slow to establish from seeds as their seedlings are relatively noncompetitive with weeds such as chickweed, common lambsquarters, and mustards. These weeds, if not controlled, can cause total failure of new legume crop stands. Many of the herbicides that are very effective in controlling the common Alaskan weeds in barley cannot be used in legume crops since they will also kill or severely damage legumes. Only a few herbicides are available for controlling broadleaf weeds in legumes. Of these, several are labeled for “established” plants only. Very little work has been done in Alaska on the effect of herbicides on legumes. The spectrum of weeds to be controlled is different from those in most temperate agricultural areas where these herbicides were developed and tested. Also, root systems of established plants in cold subarctic soils are closer to the surface than is normally true in temperate regions, thus they may be more susceptible to herbicide injury. Therefore, we decided to do a preliminary study to determine the effects of several different herbicides on selected legumes, some non-legume crops, and weeds at two sites in interior Alaska.
    • Evaluation of Forage Legume Potential at Fairbanks, Point Mackenzie, and Soldotna

      Panciera, Michael T.; Sparrow, Stephen D.; Gavlak, Raymond G.; Larson, Warren E. (Agricultural and Forestry Experiment Station, School of Agriculture and Land Resources Management, University of Alaska Fairbanks, 1990-06)
      Forage legumes have a high crude protein content and some residual nitrogen from these crops can be utilized by other species that follow legumes in crop rotations. Irwin (1945) compiled the results of early research covering a wide range of legumes, both annual and perennial, at several locations within Alaska, but neither the yields nor the persistence of these crops were comparable to native and introduced grasses. Recommended legumes included field peas and vetches in combination with cereal grains and either alsike or sweetclover in combination with bromegrass for silage (Sweetman et al., 1950). Perennial legume yields (0.5 to 1.9 tons per acre) were low when compared to perennial grasses at the Matanuska Research Farm in southcentral Alaska (Klebesadel, 1980,1983). These low yields were attributed to poor winterhardiness and consequent winterkill of most of the legumes. Formation of ice sheets, direct exposure to lethal temperatures (due to lack of snow cover), and desiccation reduce the ability of perennial legumes to survive winters in southcentral Alaska (Klebesadel, 1974). Yield potentials for perennial grasses may exceed 4.5 tons per acre (Mitchell, 1982), while forage legumes may produce from 0.5 to 2.4 tons per acre in research studies and demonstrations (Klebesadel, 1980; Mitchell, 1986). Husby and Krieg (1987) reported average crude protein contents for Alaska hays to be in the range of 8.3 to 11.8%. Changes in the production potential of Alaskan dairy cattle have effectively redefined the quality of forage that must be produced for the dairy industry. Current milk production potential for Alaska dairy cattle (14,800 lb/yr) requires high concentrations (>16%) of crude protein in the ration (Brown et al., 1989; NRC, 1988). On a dry matter yield basis legumes do not compare well with grasses, but high crude protein content and the cost of protein supplements in Alaska justify further research with both annual and perennial leguminous forage crops. Experiments were conducted to evaluate forage legumes for yield, quality, and persistence potential at three locations in Alaska. Preliminary results from these experiments are presented.
    • Nitrogen-Fixation by Legumes in Interior Alaska

      Sparrow, Stephen D.; Cochran, Verlan L.; Sparrow, Elena B. (Agricultural and Forestry Experiment Station, School of Agriculture and Land Resources Management, University of Alaska Fairbanks, 1990-11)
      Legumes are notable for their ability to convert atmospheric dinitrogen into forms of nitrogen which are usable by plants. This is done in association with bacteria (called Rhizobium) which inhabit nodules of the plant roots. This process is called nitrogen-fixation. Legumes are important as forage and food crops due to their high protein content. Some are also useful for soil conservation purposes. There was no information on nitrogen fixation by legume crops in Alaska. This research was initiated to determine how much nitrogen different types of legumes can fix in interior Alaska.