Alfalfa Management Guide E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Serie: ACSESS Books
• Sprache: Englisch

Seitenzahl: 118

Veröffentlichungsjahr: 2021

Beschreibung

Learn how to achieve top yields to maximize profits. This 2011 edition offers the latest information and strategies for alfalfa establishment, production, and harvest. Includes many color photos and charts.

Leseprobe

Table of Contents

Cover

Title Page

Acknowledgments

Copyright

Establishment

Select a field carefully

Test soil before planting

Select a good variety

Planting

Production

Fertilize annually

Irrigation

Manure management

Weed management

Disease management

Insect management

When to rotate from alfalfa

Harvest

Forage quality

Harvest management

Fall management

Hay and silage management

Forage quality terms

End User License Agreement

List of Tables

Chapter 1

Table 1. Alfalfa autotoxicity reseeding risk assessment.

Table 2. Effect of seeding rate on first-year alfalfa dry matter yields.

Chapter 2

Table 3. Pounds of nutrient removed per ton of alfalfa produced, dry matter basi...

Table 4. Sufficiency levels of nutrients, top 6 inches of alfalfa at first flowe...

Table 5. Nutrient deficiency symptoms for alfalfa.

Table 6. Estimate of available sulfur from manure as affected by animal and manu...

Table 7. Alfalfa tolerance and herbicide effectiveness in direct seedings. (Buct...

Table 8. Impact of common weeds on forage quality.

Table 9. Alfalfa tolerance and herbicide effectiveness on common weeds in establ...

Chapter 3

Table 10. Quality standards for legume, grass, and grass–legume mixture.

Table 11. Calculate your risk of alfalfa winter injury. Enter the score for answ...

Table 12. Summary of good hay-making practices.

Table 13. Summary of good alfalfa silage practices.

List of Illustrations

Chapter 1

Figure 1. Effect of autotoxicity on root development of alfalfa.

Figure 2. Effect of waiting periods when establishing alfalfa following alfalfa....

Figure 3. Available nutrients in relation to pH.

Figure 4. First-cutting alfalfa yield relative to soil pH.

Figure 5. Lime availability at different particle sizes.

Figure 6. Yield difference between top and bottom alfalfa entries in Wisconsin A...

Figure 7. Alfalfa seedling development.

Figure 8. Spring and late-summer seeding dates.

Figure 9. Effect of weed management systems for late-summer seedings on yield an...

Figure 10. Alfalfa emergence from various seeding depths.

Figure 11. Stand density during first 12 months (seeded at 12 lb/acre).

Figure 12. First-season yield and relative feed value (RFV) of alfalfa using dif...

Figure 13. Importance of packing soil after seeding.

Figure 14. Effect of seeding equipment on yield and stand in seedling year.

Chapter 2

Figure 15. Average evapotranspiration (ET) by alfalfa cut four times. Alfalfa wa...

Figure 16. Economic action thresholds for control of potato leafhopper (PLH) in ...

Figure 17. Alfalfa stem count and yield potential.

Chapter 3

Figure 18. Forage quality needs of cattle and horses.

Figure 19. Comparison of ADF to in vitro digestibility of alfalfa.

Figure 20. Carbohydrate content of alfalfa roots.

Figure 21. Forage yield relative to quality at different growth stages.

Figure 22. Cutting schedules for different management goals.

Figure 23. Dry matter yields increase with longer intervals between cuttings whi...

Figure 24. Dry matter losses during harvest and storage relative to forage moist...

Figure 25. Fat-corrected milk (FCM) yield as influenced by change in alfalfa mat...

Fig 26. Propionic acid needed to preserve hay.

Figure 27. Conditions for profitable use of inoculant on silage. Shaded areas in...

Guide

Cover

Title Page

Acknowledgments

Copyright

Table of Contents

Begin Reading

Forage quality terms

End User License Agreement

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Alfalfa Management Guide

Authors

Dan Undersander

Extension agronomist, forages University of Wisconsin

Mark Renz

Extension agronomist, weed control University of Wisconsin

Craig Sheaffer

Research agronomist University of Minnesota

Glen Shewmaker

Extension agronomist University of Idaho

Mark Sulc

Extension agronomist

The Ohio State University

Acknowledgments

The 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 Wisconsinanthracnose; aphanomyces, roots; Fusarium wilt, roots; Phytophthora, roots; root assessment; verticillium wilt, root

Dennis Cosgrove, University of Wisconsinautotoxicity

Jim Ducytitle page photo

Del Gates, Kansas State Universityalfalfa weevils

Craig Grau, University of Wisconsinaphanomyces, stunting; bacterial wilt, stunting; black stem, lesions; Fusarium wilt, field; Phytophthora, plant; sclerotinia; stand assessment; verticillium wilt, plants

B. Wolfgang Hoffmann, University of Wisconsinalfalfa plant, page 1; alfalfa flowers

Eric Holub, University of Wisconsinaphanomyces, seedling

Jeffrey S. Jacobsen, Montana State Universitynutrient deficiencies—all except boron leaf (from Diagnosis of Nutrient Deficiencies in Alfalfa and Wheat)

Pioneer Hi-Bred International, Inc. alfalfa closeups; cover photo ; cow; inside cover

Lanie Rhodes, Ohio State Universityblack stem, leaves; common leaf spot; lepto leaf spot

Marlin E. Rice, Iowa State Universityalfalfa weevil, blister beetles; clover leaf weevils; grasshopper; pea aphids; plant bug, adults; potato leafhopper, adult; spittlebug; variegated cutworm

Judy A. Thies, USDA-ARSroot-lesion nematodes

John Wedberg, University of Wisconsinalfalfa blotch leafminer; clover root curculio, damage

Thanks also to Bruce Gossen and R´eal Michaud, research scientists at Agriculture and Agri-Food Canada, for their contributions to the disease maps.

This publication is a joint effort of:University of Wisconsin-Extension,Cooperative Extension

Minnesota Extension Service,University of Minnesota

Iowa State UniversityCooperative Extension Service

Published by:

American Society of Agronomy, Inc.Crop Science Society of America, Inc.Soil Science Society of America, Inc.

© 2015 by American Society of Agronomy, Inc., Crop Science Society of America, Inc., and Soil Science Society of America, Inc.

All rights reserved. No part of this publication may be reproduced or transmitted without permission from the publishers.

The views expressed in this publication represent those of the individual Editors and Authors. These views do not necessarily reflect endorsement by the Publisher(s). In addition, trade names are sometimes mentioned in this publication. No endorsement of these products by the Publisher(s) is intended, nor is any criticism implied of similar products not mentioned.

ISBN: 978-0-89118-347-1

Library of Congress Control Number:2015956808

Editor: Lisa Al-AmoodiDesigner: Patricia Scullion

Editor previous editions: Linda DeithDesigner previous editions: Susan Anderson

Printed in the USA.

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.

Establishment

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.

Select a field carefully

Soil type, drainage, and slope

Alfalfa 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 the movement of soil oxygen 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

Fields should be free of perennial weeds such as quackgrass. If not controlled before seeding, these weeds may re-establish faster than the new alfalfa seedlings and reduce stand density.

Weed management is discussed in more detail in the Production section.

Fields should be free from herbicide carryover that may affect growth of the new alfalfa and/or companion crop. This is especially important after drought years and on fields where high herbicide application rates or late-season applications of long-lasting herbicides were used.

Autotoxicity

Alfalfa plants produce toxins that can reduce germination and growth of new alfalfa seedings. This phenomenon is known as autotoxicity. The extent of the toxin’s influence increases with the age and density of the previous alfalfa stand when it was killed.

The autotoxic compounds are water soluble and are concentrated mainly in the leaves. The compounds impair development of the seedling taproot by causing the root tips to swell and by reducing the number of root hairs (Figure 1). This limits the ability of the seedling to take up water and nutrients and increases the plant’s susceptibility to other stress factors.

Figure 1. Effect of autotoxicity on root development of alfalfa.

Source: Jennings, Nelson, and CouttsUniversities of Arkansas and Missouri, 1998

Surviving plants will be stunted and continue to yield less in subsequent years (Figure 2). A waiting period after destroying the old stand is necessary to allow the toxic compounds to degrade or move out of the root zone of the new seedlings. Weather conditions influence the speed with which the toxins are removed. Breakdown is more rapid under warm, moist soil conditions. The autotoxic compounds are removed more rapidly from sandy than more heavy textured soils. However, while the compounds are present, the effect on root growth is much more severe in sandy soils.

Figure 2. Effect of waiting periods when establishing alfalfa following alfalfa. Note that even though the number of plants is similar for all but fields planted with no waiting, yield increases dramatically.

Source: Cosgrove et al., University of Wisconsin-River Falls, 1996.

To ensure good stands, calibrate seeding depths and rates carefully and plant in a firm, moist soil.

Ideally, grow different crop for one season on sandy soils or two seasons on medium to heavy soils 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.

Test soil before planting

Proper 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.

Effect of autotoxicity on alfalfa stands when alfalfa is seeded (a) immediately following alfalfa plowdown, (b) 4 weeks later, and (c) after 1 year.

Advanced Techniques

Reseeding recommendations

Reseeding stands within 1 year carries a certain amount of risk of yield and stand failure due to autotoxicity. Use Table 1 to calculate the risk. If reseeding, consider the following:

Never interseed to thicken a stand that is 2 years old or older. Young plants that have been interseeded often look good early but die out over summer because of competition for light and moisture from the established plants.

In stands where the likelihood of successfully interseeding alfalfa is low, consider interseeding red clover or a grass species such as ryegrass or orchard-grass. These species will most likely establish well and provide good yield until new stands can be re-established.

Reseeding establishment failures

Disk down a seeding failure and reseed either in the late summer after a spring seeding or the following spring. Autotoxic compounds are not present the first year.

Reseed gaps in new seedings as soon as possible within 1 year of initial seeding.

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, and potassium. Soil tests for secondary nutrients and micronutrients are questionable. 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.

Table 1. Alfalfa autotoxicity reseeding risk assessment.

points

score

1

.

Amount of previous alfalfa topgrowth incorporated or left on soil surface

Fall cut or grazed

1

0 to 1 ton topgrowth

3

More than 1 ton topgrowth

5

2

.

Disease resistance of the variety to be seeded

High disease resistance

1

Moderate disease resistance

2

Low disease resistance

3

3

.

Irrigation or rainfall potential prior to reseeding

High (greater than 2 inches)

1

Medium (1 to 2 inches)

2

Low (less than 1 inch)

3

4

.

Soil type

Sandy

1

Loamy

2

Clayey

3

5

.

Tillage prior to reseeding

Moldboard plow

1

Chisel plow

2

No-till

3

6

.

Sum of points from Questions 1–5

7

.

Age of previous alfalfa stand

Less than 1 year

0

1 to 2 years

0.5

More than 2 years

1

8

.

Reseeding delay after alfalfa kill/plowdown

12 months or more

0

6 months

1

2 to 4 weeks

2

Less than 2 weeks

3

Your total score (multiply points from 6, 7, and 8)

Alfalfa reseeding risk

If you score:

The autotoxity risk is:

Recommendation

0

low

Seed

4–8

moderate

Caution—potential yield loss

9–12

high

Warning—yield loss likely

>13

very high

Avoid reseeding—likely stand and yield loss

Source: Craig Sheaffer, Dan Undersander, and Paul Peterson, Universities of Minnesota and Wisconsin, 2004.

Apply lime before seeding