Using Magnesium and Phosphorus Fertilization to Improve the Macronutrient Quality of Stockpiled Tall Fescue Missouri Fertilizer and Lime Council

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1 Using Magnesium and Phosphorus Fertilization to Improve the Macronutrient Quality of Stockpiled Tall Fescue 2 Missouri Fertilizer and Lime Council Grant Proposal Investigator: Dale G. Blevins, Professor of Agronomy, University of Missouri Objective: To determine if phosphorus (P) and magnesium (Mg) concentrations in leaves of stockpiled tall fescue during winter can be increased by fertilization with both P and Mg. The acreage involved makes this research important to the Missouri fertilizer industry. Missouri leads the nation in tall fescue production and is second in beef calf production (Missouri Farm Facts, 2). Of the 13 million acres of tall fescue pasture in Missouri, much of it is on soils low in plant available P (Bray I). Production of forage on these soils might have an impact on the macronutrient quality of tall fescue. Our previous work has shown that P fertilization of tall fescue pastures improved leaf P and Mg concentrations (Reinbott and Blevins 1997). Currently, it is recommended that cattle producers stockpile tall fescue to reduce winter feeding costs. However, there is very little information available on the macronutrient quality of stockpiled tall fescue and management practices to improve it. Procedure: During summer 26, an established stand of tall fescue (K31, endophyte infected) will be selected at the University of Missouri Southwest Research Center near Mt. Vernon. Soil samples will be tested for P, Mg, Ca, and K concentrations. During the third week of August, forage will be removed from the plot area. Plots of 1 x 25 with 5 foot alleys will be treated with combinations of, 5, 1, or 2 lbs P/acre and or 5 lbs Mg/acre. Each treatment combination will be replicated six times. From mid-ober through mid-il, 2 of the most recently collared leaves will be harvested monthly from each plot. Samples will be dried, ground and digested in nitric acid in a microwave accelerated digestion system (CEM Corp.). Digested samples will be filtered, diluted and K will be determined by flame ionization, Mg and Ca by atomic absorption, and P by colorimetric analysis. This study will be completed after two years of harvests. Data will be analyzed by SAS and graphs will be prepared by plotting macronutrient concentrations versus month of the year and treatments. Current status/importance of research area: Very little research has been reported on the macronutrient concentrations of stockpiled tall fescue during winter and early spring. One study from West Virginia reported the effects of nitrogen fertilization on the quality of stockpiled tall fescue and found that levels of P and Mg in the forage dropped during the winter months (Collins and Balasko, 1981). Our current and past research funded by this Fertilizer and Lime Board indicates that high rates of P fertilization increase P concentrations of stockpiled tall fescue leaves and produce levels that are above the requirements for lactating beef cows in late winter and early spring (Fig. 1). In addition, leaf Mg concentrations were higher in the P treated plots compared to the untreated plots (Fig. 2). However, by late winter leaf Mg concentrations fell below levels required by lactating beef cows, therefore diets of lactating beef cows grazing stockpiled tall fescue may need to be supplemented with grain, alfalfa hay or mineral blocks to provide Mg in the late winter and early spring. Our earlier work indicated a boost in Mg levels in tall fescue leaves during ch and il only when P was also applied to low P soils or when soil P levels were high (Reinbott and Blevins, 1997). Application of Mg fertilizer alone failed to increase leaf Mg levels on low P soils. Fertilization of low P soil with both P and Mg could raise the concentrations of these elements in leaves to levels where they remain above the recommend levels for lactating beef cows in late winter and early spring. We have made significant progress

2 in P fertilization studies for increasing tall fescue leaf P concentration, however, we need to improve Mg levels during the late winter (Fig. 3 & 4). Results from our latest study confirm that in late winter and early spring leaf Mg concentrations of most P treatments fall below the.2% required for lactating beef cows (Fig. 4). The next logical step is to determine if Mg fertilization combined with P fertilization of stockpiled tall fescue maintains the required levels of P and Mg for lactating beef cows in winter and early spring. Timetable for proposed research: In early 26, soil will be sampled at several tall fescue sites at the Southwest Center and analyzed at the University of Missouri Soil Testing Laboratory. A site with an established stand of tall fescue and soil P levels (Bray I) below 1 lbs/acre will be selected for this project. During the third week in August, tall fescue forage will be removed. Plot areas will be flagged then treated with the combinations of P and Mg fertilizer. Leaf samples will be collected monthly from mid-ober to mid-il. Harvested samples will be dried, ground, digested and analyzed for macronutrient concentrations. On the third weeks of May and August hay yields will be taken, measured, dried, ground and analyzed for macronutrient levels. These data will be analyzed and compared to the nutrient requirements of grazing beef cows. During the summer of 28, results form this two year study will be prepared for publication in a refereed journal. Strategy for application and transfer of knowledge: The results of this study will be presented at Southwest Center Field Days, as well as several meetings of the Missouri Cattlemen s Association, Forage meetings in the state, and at the North Central Extension-Industry Soil Fertility Conference. The final results of this research will be presented at the annual meeting of the American Society of Agronomy and published in a refereed journal. Reference List: Reinbott, T.M. and D.G. Blevins Phosphorus and magnesium fertilization interaction with soil phosphorus level: Tall fescue yield and mineral element content. J. Production Agriculture 1: Collins, M., and Balasko, J.A Effects of N fertilization and cutting schedules on stockpiled tall fescue. I. Forage yield. Agron. J. 73:8-87. List of Figures: P % P 12.5 P 25 P Figure 1. Phosphorus concentrations of stockpiled tall fescue leaves treated with, 12.5 or 25 lbs P/acre. Means ± S.E. (n = 18) for each month. The bold line at.2% indicates the nutrient

3 .45 Mg % P 12.5 P 25 P Figure 2. Magnesium concentrations of stockpiled tall fescue leaves treated with, 12.5 or 25 lbs P/acre. Means ± S.E. (n = 18) for each month. The bold line at.2% indicates the nutrient % Phosphorus LP 1LP 5LP LP Figure 3. Phosphorus concentrations of stockpiled tall fescue leaves treated with, 5, 1, or 2 lbs P/acre. Means ± S.E. (n = 6) for each month. The bold line at.2% indicates the nutrient % Magnesium LP 1LP 5LP LP Figure 4. Magnesium concentrations of stockpiled tall fescue leaves treated with, 5, 1, or 2 lbs P/acre. Means ± S.E. (n = 6) for each month. The bold line at.2% indicates the nutrient

4 Budget: Category Year 1 Year 2 Salary Research Assistant (5%) $16, $17, Benefits 4, 4,25 Supplies (fertilizer, chemicals, DI H 2 O, pipettes, nitric acid) 2, 2, Travel to Mt. Vernon 1, 1, Total $23, $24,25 Resume: Dale G. Blevins - Professor of Agronomy Present Address Division of Plant Sciences phone Agriculture Building fax University of Missouri blevinsd@missouri.edu Columbia, MO Education B.S. in Chemistry, Southwest Missouri State University, 1965 M.S. in Soils (Plant Nutrition), University of Missouri, 1967 Ph.D. in Plant Physiology, University of Kentucky, 1972 Experience present, Professor, Agronomy Department, U. Missouri, Columbia Associate Professor, Agronomy Department, U. Missouri, Columbia Assistant Professor, Agronomy Department, U. Missouri, Columbia Assistant Professor, Botany Dept., U. yland, College Park Postdoctoral Research Associate, Department of Botany and Plant Pathology, Oregon State University, Corvallis Awards 1982 Gamma Sigma Delta Superior Research Award for Junior Faculty in Agriculture 1983 Amer. Soybean Assoc./ ICI International Soybean Researchers Recognition Award 1983 Gamma Sigma Delta Superior Graduate Teaching Award 1992 Fellow of the American Society of Agronomy 1992 Fellow of the Crop Science of America 1992 Distinguished Faculty Award, UMC Alumni 1993 Kemper Teaching Award, UMC Selected Publications Reinbott, T.M. and D.G. Blevins Phosphorus and magnesium fertilization interaction with soil phosphorus level: Tall fescue yield and mineral element content. J. Production Agriculture 1: Reinbott, T.M., D.G. Blevins and M.K. Schon Content of boron and other elements in main stem and branch leaves and seed of soybean. J. Plant Nutrition 2:

5 Blevins, D.G. and T.M. Reinbott Impact of phosphorus nutrition on magnesium, calcium and water status of plants. Current Topics in Plant Physiology: An American Society of Plant Physiologists Series 19: Blevins D.G. and K.M. Lukaszewski Boron in plant structure and function. Annual Review of Plant Physiology and Plant Molecular Biology 49: kwell, J. and D.G. Blevins The Minolta Spad-52 leaf chlorophyll meter: An exciting new tool for education in the plant sciences. The American Biology Teacher 61: Reinbott, T. M. and D.G. Blevins Phosphorus nutritional effects on root hydraulic conductance, xylem water flow and flux of magnesium and calcium in squash plants. Plant and Soil 29: Waters, B.M. and D.G. Blevins. 2. Ethylene production, cluster root formation and localization of iron (III) reducing capacity in Fe deficient squash roots. Plant and Soil 225: Smith, G.J., W.J. Wiebold, T.L. Niblack, P.C. Scharf and D.G. Blevins. 2. Yield components of soybean plants infected with soybean cyst nematode and sprayed with foliar applications of boron and magnesium. J. Plant Nutrition 23: Smith, G.J., W.J. Wiebold, T.L. Niblack, P.C. Scharf and D.G. Blevins. 21. Macronutrient concentrations of soybean infected with soybean cyst nematode. Plant and Soil 235: Lock, T.R., R.L. Kallenbach, D.G. Blevins, T.M. Reinbott, G.J. Bishop-Hurley, R.J. Crawford, Jr. and M.D. Massie. 21. Soil phosphorus may be important to beef herd health and performance. Better Crops with Plant Food 85:4-8. Waters, B.M., D.G. Blevins and D.J. Eide. 22. Characterization of FRO1, a pea (Pisum sativum) ferric-chelate reductase involved in root Fe uptake and tissue Fe distribution. Plant Physiol. 129:1-1. Lock, T.R., R.L. Kallenbach, D.G. Blevins, T.M. Reinbott and G.J. Bishop-Hurley. 22. Adequate soil phosphorus decreases the grass tetany potential of tall fescue pasture. Online. Crop Management doi:1.194/cm rs. Lock, T.R., R.L. Kallenbach, D.G. Blevins, T.M. Reinbott, G.J. Bishop-Hurley, R.J. Crawford, M.D. Massie and J.W. Tyler. 2. Plant Management Network. June 8:1-8. Reinbott, T.M., S. P. Conley, and D. G. Blevins. 2. No-Tillage Corn and Grain Sorghum Response to Cover Crop and Nitrogen Fertilization Agron. J. 96: Blevins, D.G., M. Massie and W. McClain. 2. Phosphorus fertilization improves quality of stockpiled tall fescue. Better Crops with Plant Food 88:7-9. Bolanos, L., K. Lukaszewski, I. Bonilla and D. Blevins. 2. Why boron? A Reviw. Plant Physiology and Biochemistry 42: Todd, C.D., P.A. Tipton, D.G. Blevins, P. Piedras, M. Pineda and J.C. Polacco. 2. Update on ureide degradation in legumes. J. Experimental Botany. doi:1.193/jxb/erj13