Browsing by Subject "Agronomy"
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Item Agronomy Gleanings, 1978 - 1981(University of Minnesota, 1978) University of Minnesota: Department of Agronomy and Plant GeneticsItem Agronomy Gleanings, 1982 - 1985(University of Minnesota, 1982) University of Minnesota: Department of Agronomy and Plant GeneticsItem Agronomy Gleanings, 1985 - 1987(University of Minnesota, 1985) University of Minnesota: Department of Agronomy and Plant GeneticsItem Agronomy Gleanings, 1988 - 1990(University of Minnesota, 1988) University of Minnesota: Department of Agronomy and Plant GeneticsItem Agronomy Gleanings, 1991 - 1993(University of Minnesota, 1991) University of Minnesota: Department of Agronomy and Plant GeneticsItem Agronomy Gleanings, 1994 - 1995(University of Minnesota, 1994) University of Minnesota: Department of Agronomy and Plant GeneticsItem Agronomy Gleanings, 1996 - 1998(University of Minnesota, 1996) University of Minnesota: Department of Agronomy and Plant GeneticsItem Agronomy Gleanings, 1999 - 2000(University of Minnesota, 1999) University of Minnesota: Department of Agronomy and Plant GeneticsItem Agronomy Gleanings, 2002(University of Minnesota, 2002) University of Minnesota: Department of Agronomy and Plant GeneticsItem Agronomy Gleanings, 2003(University of Minnesota, 2003) University of Minnesota: Department of Agronomy and Plant GeneticsItem Agronomy Gleanings, 2004(University of Minnesota, 2004) University of Minnesota: Department of Agronomy and Plant GeneticsItem Agronomy Gleanings, 2005(University of Minnesota, 2005) University of Minnesota: Department of Agronomy and Plant GeneticsItem Agronomy Gleanings, 2006(University of Minnesota, 2006) University of Minnesota: Department of Agronomy and Plant GeneticsItem Agronomy Gleanings, 2007(University of Minnesota, 2007) University of Minnesota: Department of Agronomy and Plant GeneticsItem Agronomy Gleanings, 2008(University of Minnesota, 2008) University of Minnesota: Department of Agronomy and Plant GeneticsItem Agronomy Gleanings, 2009(University of Minnesota, 2009) University of Minnesota: Department of Agronomy and Plant GeneticsItem Agronomy Gleanings, 2011(University of Minnesota, 2011) University of Minnesota: Department of Agronomy and Plant GeneticsItem Fertilizer Guidelines for Agronomic Crops in Minnesota(University of Minnesota Extension, 2023-07-27) Kaiser, Daniel EItem Nitrogen Management for Corn Following Alfalfa: Field, Literature, and Geographic Analyses(2013-12) Yost, Matt AlanFirst- and second-year corn (Zea mays L.) following alfalfa (Medicago sativa L.) often require less supplemental N than corn grown continuously or following soybean [Glycine max (L.) Merr.]. The results of seven on-farm trials indicated that alfalfa can provide the entire N requirement of first-year corn no-till planted following alfalfa terminated in the fall. Eight other on-farm trials also indicated that first-year corn following alfalfa often does not require supplemental N (fertilizer or manure). The conclusion that first-year corn following alfalfa often requires no fertilizer N has been supported for decades, yet no research has identified site-specific conditions that cause first-year corn to respond to supplemental fertilizer N. The most widely used predictive test, the presidedress soil nitrate test (PSNT), had limited success in identifying response to N when trials from this study were combined with literature research; the test was 55% accurate across 94 site-years. An end-of-season test used to assess N supply to corn, the corn stalk nitrate test (CSNT), also was not successful in 11 trials at identifying when first-year corn would have required fertilizer N. An analysis of the literature was conducted to identify site-specific conditions that cause first-year corn following alfalfa to respond to N. Soil texture and alfalfa termination timing on medium-textured soils were significant covariates for identifying responsiveness to fertilizer N in first-year corn. First-year corn following alfalfa rarely required fertilizer N when alfalfa harvested for ¡Ý2 yr was fall-terminated on medium-textured soils; corn following alfalfa harvested 1 yr responded more frequently. The frequency of response to fertilizer N increased greatly when alfalfa was grown on coarse- or fine-textured soils and when alfalfa was terminated in the spring on medium-textured soils. For these conditions, combinations of alfalfa stand age and weather conditions explained much of the variation in whether a site would respond to N and the economically optimum N rate (EONR) at various price ratios (PRs) of fertilizer N/corn grain. The regression models developed to predict fertilizer N response appear robust, but require independent validation. Alfalfa also provides N to the second consecutive corn crop following alfalfa termination. Results from 28 on-farm trials in Minnesota and Iowa revealed that second-year corn required fertilizer N only 50% of the time. The same trend occurred when these trials were combined with 39 trials in the literature. The PSNT had higher accuracy for second-year corn (65%) than for first-year corn, but improvements in accuracy are still necessary in order for this test to be a reliable tool for growers. A geographic analysis revealed that growers in the U.S. Corn Belt region of the upper midwestern United States (North Dakota, South Dakota, Nebraska, Minnesota, Iowa, and Wisconsin) rotate alfalfa more frequently than in other parts of this region and that alfalfa phase length, soil texture, and year affect the type of crops grown for 2 yr following alfalfa termination. Supplemental files include data and references used for the literature analysis (Supplemental Table S4.1; Supplement S4.2), data used for analysis of second-year corn response to N (Supplemental Table S5.1), and alfalfa hectare estimates by state and year for the geographic analysis (Supplemental Table S6.1).Item Production Of Native Plants For Seed, Biomass, And Natural Products(2020-03) Freund Saxhaug, KatrinaNative and naturalized perennial plants are important components of sustainable agricultural systems, providing a wide range of ecosystem services including marketable products. Although demand for these products is increasing, there is limited information on the establishment and production of native and naturalized perennial plants. Through field and greenhouse studies, four native and naturalized perennial plant species were evaluated for their seed yield, biomass yield, and phytochemical (natural product) production. Canada milk vetch (Astragalus canadensis L.), purple coneflower (Echinacea purpurea Moench [L.]), and showy tick trefoil (Desmodium canadense L.) were evaluated in the field for seed and biomass production over three consecutive years. Seed yield decreased in all three species over time, whereas biomass yields over time varied by species. Seed and biomass yields, on a per hectare basis, decreased as the number of rows decreased, and there was little effect of plant community richness or diversity. An untargeted metabolomics approach was taken to evaluate phytochemical production in purple coneflower tissues. Several bioactive compounds were provisionally identified in purple coneflower tissues, and seed tissue possessed a similar profile to that of root. Although the plant community did not affect the overall metabolomic profile of purple coneflower, levels of specific compounds in leaf, stem, and root tissue were affected. Similar biomass yield and metabolomics approaches were applied to fireweed (Chamaenerion angustifolium (L.) scop., syn. Epilobium angustifolium L.) grown in a hydroponic system. Shoot dry weight increased logistically with increasing mineral concentration of the nutrient solution. Although the abundance of most provisionally identified compounds decreased with increasing mineral nutrient concentration, commercially-relevant oenothein B and miquelianin were not affected by mineral nutrient treatments. Native and naturalized perennial plants on the agricultural landscape can provide numerous ecosystem services, including marketable products such as seed for restoration plantings, biomass for fuel and forage, and bioactive phytochemicals for medicinal and supplemental purposes. In order to incentivize the establishment of native and naturalized perennials for such marketable products, research on the productivity of specific plants is needed. The research presented in this dissertation provides the groundwork for four native and naturalized Minnesota species.