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NCR547 North Central Regional Extension.Publication L :::e ~ AUTHORS Dan Undersander Extension agronomist,forages University ofwisconsin Neal Martin Extension agronomist,forages University of Minnesota
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NCR547 North Central Regional Extension.Publication L :::e ~ AUTHORS Dan Undersander Extension agronomist,forages University ofwisconsin Neal Martin Extension agronomist,forages University of Minnesota Dennis Extension Cosgrave agronomist,forages UniversityofWisconsin Keith Kelling Extension soils scientist University ofwisconsin Mike Schmitt Extension soils scientist University of Minnesota John Wedberg Extension entomologist University ofwisconsin Extension agronomist, weed control University of Minnesota Craig Plant Grau pathologist University ofwisconsin Jerry Doll Extension agronomist, weed control University ofwisconsin Marlin E. Rice Extension entomologist Iowa State University ACKNOWLEDGMENTS T he authors wish to thank reviewers from industry and various universities for their suggestions and everyone who supplied photos, including those not specifically mentioned: Steve Bicen, University of Wisconsin anthracnose; aphanomyces, roots; Fusarinm wilt, roots; Phytophthora, roots; root assessment; verticillium wilt, root Jim Ducy title page photo Del Gates, Kansas State University alfalfa weevil, Craig Grau, University of Wisconsin aphanomyces, stunting; bacterial wilt, stuntiug; black stem, lesions; Fusarium wilt, field; Phytophthora, plant; sclerotinia; verticillium wilt, plants Eric Holub, University of Wisconsin aphanomyces, seedling JeHrey S. Jacobsen, Montana State University nutrient deficiencies-all except boron leaf {from Diagnosis of Nutrient Deficiencies in Alfalfa and Wheat) Pioneer Hi-Bred International, Inc. alfalfa closeups; cover photos; cow; inside cover lanie Rhodes, Ohio State University black stem, leaves; common lepto leaf spot leaf spot; Marlin E. Rice, Iowa State University alfalfa weevil, damage; blister beetles; clover leaf weevils; grasshopper; pea aphids; plant bug, adults; potato leajhoppel; adult; spittlebug; variegated cutworm Judy A. Thies, USDA-ARS root-lesion nematodes John Wedberg, University of Wisconsin clover root curculio, damage This publication is a joint effort of: University ofwisconsin- Extension, Cooperative Extension Minnesota Extension Service, University of Minnesota Iowa State University Cooperative Extension Service Produced by: Cooperative Extension Publications, University Editor: Linda Deith Designer: ofwisconsin-extension. Susan Anderson Published by: American Society of Agronomy, Inc. Crop Science Society of America, Inc. Soil Science Society of America, Inc. (i;;) 1994 by the American Society of Agronomy, Inc., Crop Science Society of America, Inc., and Soil Science Society of America, Inc. All rights reserved under the US. Copyright Law of 1978 (RL ) Any and all uses beyond the limitations of the 'Jair use provision of the law require written permission from the publishers; not applicable to contributions prepared by officers or employees of the U S. Government as part of their official duties. Library of Congress Cataloging-in-Publication Data Alfalfa management guide/ authors, Dan Undersander...[et al.]. p. cm. ISBN Alfalfa. I. Undersander, D.J. SB205.A4A '1-dc CIP Establishment... Select Soil type, a field drainage, carefully. and slope.. Control perennial weeds.... Test Autotoxicity soil before planting.... Apply lime before seeding... Nutrient needs during Select Planting. Yield Winterhardiness Persistence. Disease Forage Intended Time Field Seeding establishment. a inoculation. preparation. potential. of quality good resistance. depth seeding. use. variety and rate Seeding with and without a Reduced Seeding compamon equipment. tillage crop. and no-till planting. CONT NT 2 Disease management Anthracnose. Aphanomyces root rot Bacterial Common wilt. leaf spot and Phytophthora Fusarium lepto leaf wilt. spot. root rot Root-lesion nematodes Sclerotinia. Spring Summer black black stem. stem Insect Verticillium management. wilt Alfalfa weevil Aphids. Blister Clover beetles. leaf root weevil. curculio Plant Potato Grasshoppers. bugs. leafhoppers Variegated Spittlebugs. cutworm When to rotate from 15 alfalfa. 40 Production... Fertilize Determine Nitrogen. Phosphate annually. and needs. potash... Secondary nutrients.... Manure Micronutrients management.. Weed management... Weed management before Weed planting. management in the Harvest.42 Forage quality 43 What quality forage is needed?.43 Plant growth and forage quality.44 Harvest management. 44 Cutting schedule. 45 Fall management. 46 Hay and silage management. 48 Feeding considerations of hay and haylage 50 Weed seeding management year. in 21 established alfalfa Profitable forage production depends on high yields. Land, machinery, and most other operating costs stay the same whether harvesting 3 tons per acre or 6 tons per acre. Top yields in the northern United States have approached 10 tons per acre while average yields are around 3 tons per acre. This booklet describes what it takes to move from a 3-ton yield to 6 or 9 tons per acre. A vigorously growing, dense stand of alfalfa forms the basis for profitable forage production. Profitable stands are the result of carefully selecting fields with well-drained soil, adding lime and nutrients if needed, selecting a good variety, and using appropriate planting practices to ensure germination and establishment. ESTAB SHM NT3 SELECT A FIELD CAREFULLY Soil type, drainage, and slope A lfalfa requires a well-drained soil for optimum production. Wet soils create conditions suitable for diseases that may kill seedlings, reduce forage yield, and kill established plants. You can reduce some disease problems associated with poor drainage by selecting varieties with high levels of resistance and by using fungicides for establishment. Poor soil drainage also reduces soil oxygen movement to roots. Poor surface drainage can cause soil crusting and ponding which may cause poor soil aeration, micronutrient toxicity, or ice damage over winter. Even sloping fields may have low spots where water stands, making it difficult to maintain alfalfa stands. Soils should be deep enough to have adequate water-holding capacity. Alfalfa has a long taproot that penetrates more deeply into the soil than crops such as corn or wheat which have more fibrous, shallow roots. Under favorable conditions, alfalfa roots may penetrate over 20 feet deep. This great rooting depth gives alfalfa excellent drought tolerance. Sloping fields where erosion is a problem may require use of erosion control practices such as planting with a companion crop or using reduced tillage to keep soil and seed in place until seedlings are well rooted. Control perennial weeds The auto toxic compound, Fields should be free of perennial medicarpin, is water soluble and is weeds such as quackgrass. If not concentrated mainly in the leaves. A controlled before seeding, these weeds may re-establish faster than the new waiting period after destroying the old stand is necessary to allow this toxic alfalfa seedlings and reduce stand compound to degrade or move out of density. Weed management is discussed the root zone of the new seedlings. in more detail in the Production Weather conditions influence the section. Fields should be free from herbicide carryover that may affect growth of the new alfalfa and/ or companion crop. This is especially important dl1ring droughts or on fields where high herbicide application rates or late-season applications oflong-acting herbicides were used. A t t.. ty alfalfa. U O OXICI Alfalfa plants produce a toxin that can reduce germination and growth of new alfalfa seedings. This phenomenon is known as auto toxicity. The extent of the toxin's influence increases with the age and density of the previous stand and the amount of residue incorporated prior to seeding. speed with which the toxins are removed. Breakdown is more rapid under warm, moist soil conditions. Ideally, grow a different crop for one season after plowing down or chemically killing a 2-year or older stand before seeding alfalfa again in the same field. This is the best and safest way to manage new seedings of Alfalfa planted, left, in soil from a corn field (no autotoxicity) and, right, in soil from an alfalfa field (autotoxicity). 4 A A A MANAG M NT G u D TEST SOIL BEFORE PLANTING p roper fertility management, including an adequate liming program, is the key to optimum economic yields. Proper fertilization of alfalfa allows for good stand establishment and promotes early growth, increases yield and quality, and improves winterhardiness and stand persistence. Adequate fertility also improves alfalfa's ability to compete with weeds and strengthens disease and insect resistance. Fields differ in their fertilizer needs. Soil testing is the most convenient and economical method of evaluating the fertility levels of a soil and accurately assessing nutrient requirements. Most soil testing programs make recommendations for ph and lime, phosphorus, potassium, and several of the secondary nutrients and micronutrients. Optimal soil test levels for alfalfa differ among states due to varying subsoil fertility, nutrient buffering capacities, soil yield potentials, and different management assumptions. For more detailed information on soil test recommendations, contact your local Extension office. E s T A B SHM NTS Apply before Because lime reacts very slowly Liming is the single most impor- with soil acids, it should be applied tant fertility concern for establishing 12 months-preferably longer-before and maintaining high yielding, high seeding. For typical 4- to 6-year crop quality alfalfa stands. Benefits of liming rotations, the best time to apply the alfalfa include: recommended amount oflime is when.increased stand establishment and coming out of alfalfa. This allows more persistence, time for reaction with the soil. The.more activity of nitrogen-fixing accompanying tillage for rotation crops Rhizobium bacteria may result in two or three remixings, of the lime with the soil. This should.added calcium and magnesium,. th H t h d. raise e p o t e esire d 1eve 1by t he.improved soil structure and tilth, ti~e alfalfa is replanted..increased availability of phosphorus and molybdenum (figure 1), and.decreased manganese, iron and aluminum toxicity (figure 1). For maximum returns, lime fields to at least ph 6.7 to 6.9. Field trials performed in southwestern Wisconsin show that yields drop sharply when soil ph falls below 6.7 (figure 2)..., Figure 2. first-cutting alfalfa yield relative to soil ph Figure 1.Available nutrients in relation to ph ~ u O ~ ~ i 0 -.. Qj... ȯ E ... ~ ph Source: /MJllenhaupt and Undersandel; UniversityoJWisconsin, acidic ph basic 6 -A A A MANAG M NT G u D Lime effectiveness is determined by its chemical purity and the fineness to which it is ground. Figure 3 illustrates the greater effectiveness of more finely ground lime. To achieve the same ph change, coarse aglime must be applied further in advance and at higher rates than fine aglime but is usually less expensive per ton. It may not be necessary to re-lime as often where some coarse lime is used. When comparing prices, be sure to evaluate materials on the basis of amounts oflime needed to achieve similar effectiveness. The relative effectiveness of various liming materials is given by its lime grade, effective calcium carbonate equivalency (ECCE), effective neutralizing power (ENP), or total neutralizing power (TNP).soil Aglime should be broadcast on the surface of the soil, disked in, and then plowed under for maximum distribution and neutralization of acids in the entire plow layer. Plowing without disking may deposit the lime in a layer at the plow sole. For high rates oflime ( 6 tons/acre), apply half before working the field; work the remaining half into the soil after plowing or other field preparation. Liming materials come in several forms. Calcitic products contain calcium-based neutralizers while dolomitic sources contain both calcium and magnesium. Both are equally effective for changing soil ph. Some claims are made that when the calcium to magnesium ratios in the are low, calcitic limestone should be used. Research evidence does not support these claims, as virtually all midwestern and northeastern soils have ratios within the optimal range. Dolomitic limestone itself has a calcium to magnesium ratio within the normal range for plant growth. The addition of calcitic limestone or gypsum for the purpose of adding calcium or changing the calcium/magnesium ratio is neither recommended nor cost effective. Several by-products, such as papermilllime sludge and water treatment plant sludge may be used as liming materials. Since the relative effectiveness of some of these materials is highly variable, be sure you know its Figure 3. Lime availability at different particle sizes. ellectlve «. neutr ali zmg. power. III C ~ M Qj ~ 60 Qj Dl C ] 40 c.... ~ QI c ~ 60 aglime particle size (mesh) E s T A B SHM NT7 Nutrient needs during establishment Tillage during establishment provides the last opportunity to incorporate relatively immobile nutrients during the life of the stand. Typical nutrient additions tend to include phosphorus, potassium, and sulfur. Phosphorus. Adequate soil phosphorus levels increase seeding success by encouraging root growth. Phosphorus is very immobile in most soils. Wisconsin research confirms that at low to medium soil test levels incorporated phosphorus is more than twice as efficient as topdressed phosphorus. Potassium. Research has shown that although potassium has relatively little influence on improving stand establishment, yield and stand survival are highly dependent on an adequate potassium supply. When soil tests are in the medium range or below, sufficient potassium should be added to meet the needs of the seeding-year crop including the companion crop. Sulfur. Elemental sulfur, where needed, can be used as the sulfur source and may be applied at seeding. Elemental sulfur must be converted to sulfate-sulfur before it can be used by plants. This process is relatively slow, especially when sulfur is top dressed. Therefore, incorporating moderately high rates (50 lb/acre sulfur) of elemental sulfur at establishment will usually satisfy alfalfa sulfur requirements for the life of the stand. The cost of this treatment should be compared to the cost of annual top dressed applications of sulfate-sulfur. Nitrogen. Recent research has shown that small additions of nitrogen may enhance establishment and firstyear yields. Apply 25 to 30 Ib/acre nitrogen when alfalfa is direct seeded J on coarse-textured soils with 10 organic matter contents «2%). Appl)' 20 to 35 Ib/acre nitrogen when seeding alfalfa with a companion crop and apply 40 to 55 Ib/acre nitrogen if you will be harvesting, the companion crop as silage..l,j. Manure may be successfully applied prior to alfalfa establishment if adequate weed control practices are followed. Recent Minnesota and Wisconsin research has shown that preplant manure application can maintain or even increase yields the first two years. When spreading manure avoid compacting soil and be sure that the manure is adequately incorporated so that seed is not planted directly into high-manure application zones. SELECT A GOOD VARIETY p lant breeders have developed alfalfa varieties with greater yield potenrial and disease resistance and improved forage quality. But with over 250 varieties available, how does one select an alfalfa variety? The major factors leading to profitability are:.yield potential,.persistence (percent stand remaining or estimated from winterhardiness and disease resistance ratings),.winterhardiness,.disease resistance, and.forage quality. As illustrated in table 1, yield has the largest effect on profitability, persistence next, and other factors have a lesser effect. Table'.Factors Influencing dollar return per acre for alfalfa from milk production. Source: Undersandet; University ofwisconsin, CP = crude protein; ADF = acid detergent fiber; NDF = neutral detergent fibel: ~ 8 - -A A A MANAG M N T G u D Yield potential Look for varieties with high yields in university trials. Compare new varieties to Vernal, a winterhardy check variety. Comparing varieties to the same check, planted within the trial, also allows comparison across several trials. New varieties should perform better than Vernal. In Wisconsin and Minnesota variety trials over the last 10 years, the top varieties have yielded up to 0.89 tons more per acre than Vernal for each year of stand life (figure 4). For short-term stands, select varieties by yield from 2- to 3-yearold stands. For long-term stands, select by yield from 4- to 5-year-old stands. Varieties will perform differently in various growing regions. Look for top yields of a variety grown in a site with as similar a soil type and climate to your farm as possible. Also, look for top yield over several sites. This indicates stability for high yield and is important because soils may vary on your farm and weather conditions change from year to year. Persistence Compare stand survival ratings or yields of 4- to 5-year-old stands to determine relative persistence of varieties. Persistence in northern locations is most dependent on winterhardiness because of the severity of winter temperatures (figure 5), while farther south persistence is more dependent on disease resistance levels. In the absence of stand survival ratings or yields of 4- to 5-year-old stands, use winterhardiness and disease resistance to estimate persistence. Figure Source: USDA 5. Winterhardiness zones.,~ i.!!: ~ Winterhardiness Winterhardiness is dependent on cold tolerance, fall dormancy, and resistance to root and crown diseases. Lack of winterhardiness may result in winter injury and winterki1l. Winter injury slows spring growth-meaning fewer shoots for first cutting and a lower yield. The best indicator of winterhardiness is stand survival ratings (count oflive plants) the spring following a severe winter. Generally, varieties with less winterhardiness have greater yield potential because of faster regrowth. Planting several fields of alfalfa, each with different winterhardiness ratings ensures stand survival of some fields in severe winters and increases yield potential in others. cm~a '1, CC range minimum of average temperatures 10 for each zone zone 1- below -50 F zone 2CJ-50 to -40 F zone 3G-40 to -30 F zone 4~-30 to -20 F zone to -]0 F zone6~-]o to o F :# m Figure 4. Yield increase over Vernal of top five varieties in Wisconsin and Minnesota from 1980 to The two plants on right show severe winter injury. Damaged plants are slow to regrow and produce few stems. s T A B SHM NT9 Disease resistance Diseases may cause seedling death, reduce stand density, lower yields, and shorten stand life. The best disease management strategy is to select varieties with high levels of disease resistance. Determine potential for diseases on your farm and select alfalfa varieties with resistance to as many of them as possible. Knowing which diseases have occurred in your fields will help you choose varieties with the appropriate resistance. Look over the descriptions and pictures in the disease section of this booklet, learn to recognize them and select resistant varieties if the disease is occurring in your field. To estimate the potential for each disease to occur in your area, refer to the maps in the disease management section. Forage quality Many new varieties coming on the market have improved forage quality. Evaluate alfalfa varieties based on estimated digestibility, intake and relative feed value compared to Vernal, the standard variety. Intended use Most alfalfa is planted for harvest as hay or haylage with plans to keep stands as long as they are productive. Special situations may require different variety selection criteria. For example, when a short rotation is desired or when nitrogen for other crops is needed, yield is more important than persistence so select varieties with high yields in the first tw
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