Forage establishment: getting it to grow

Table of contents

• Introduction
• Seeding
  • The seedbed
  • Seed placement
  • Seeding date
  • Seeding equipment
  • Seeding rate
  • Calibrate the seeding equipment
  • Row spacing and seeding pattern
  • Legume inoculation
  • Companion crops
  • Weed control
  • Insects
  • Seeding saline areas
  • Evaluation
• Why do forage seedlings fail?

The authors thank the Saskatchewan Forage Council, the Saskatchewan Advisory Council on Forage Crops and the following for their helpful suggestions while drafting this publication: H. Bjorge, G. Chu, D. Clark, B. Dyck, D. Fraser, N. Fraser, B. Goplen, R. Jones, N. Holt, P. Jefferson, L. Moats, C. Nykoluk, K. Stoner and J. Moen for his efforts in coordinating this project.

This publication is sponsored by Saskatchewan Wheat Pool, Ducks Unlimited Canada, Saskatchewan Soil Conservation Association, SeCan Association, Saskatchewan Wetland Conservation Corporation, and PFRA through the Canada-Saskatchewan Agreement on Soil Conservation

PHOTO CREDITS:
Agriculture Canada, PFRA and Research Branch, Ducks Unlimited Canada, Saskatchewan Agriculture and Food, Saskatchewan Agriculture and Food, Saskatchewan Rural Development, Saskatchewan Soil Conservation Association, Saskatchewan Wheat Pool, SeCan Association, H. Bjorge and D. McCartney

Introduction

Proper establishment is an important step in any successful forage stand. This booklet is intended as a guide to help in your preparation and seeding.

Seeding

A few basic guidelines will help you establish a successful forage stand.

• Seed shallowly in firm, moist soil on an appropriate date.
• Minimize competition from weeds, companion crops and pests to allow early development of strong plants.
• Avoid exposing the soil to wind and water erosion.

This publication examines these guidelines in detail, with special emphasis on seeding.

THE SEEDBED

Firmness

The seedbed must be firm to permit shallow seed placement and promote good contact with firm, moist soil. The following usually provide ideal seedbeds:

• Annual crop stubble.
• Chemfallow.
• Summerfallow unworked in the spring before seeding.

Avoid tillage for seedbed preparation as it dries out the soil surface and increases the risk of erosion. If the field must be tilled before seeding, pack it well to restore firmness and preserve moisture. Consider delaying the seeding of tilled fields until a good rain has firmed up the soil and replenished the moisture.

Seedling protection

The seedbed should shelter emerging seedlings from heat, wind and water action. This is particularly important in more arid areas and where the soil is subject to erosion. Standing stubble is excellent for this purpose. A companion annual crop seeded at a liquid rate protects stands seeded in bare fields. See companion crops section.

Crop residues

Crop residues protect soil erosion, but excessive residues make good seed placement difficult. To allow seedling into standing stubble, finely chop excess straw and spread it well; as a last resort, bale it and remove it. Get a good spread of chaff behind the combine.

Weeds

The field should be relatively free of perennial weeds, particularly those which cannot be controlled "in crop" with herbicides. If these are a problem, bring them under control in annual crop rotations before seeding forages.

Control winter annuals with herbicide (e.g., 2, 4-D) applied in the late fall before seeding.

Destroy annual weeds and volunteer grains, before seeding, with "burn-off" herbicide (e.g. glyphosate at 0.4 to 0.5 litres/acre) in preference to tillage.

Herbicide Residues

Residues of some herbicides can damage forage seedlings. If such herbicides have been used in the field proposed for forage, seed only species tolerant to the residues or wait the appropriate time before planting susceptible species. Refer to Weed control in field and forage crops( Saskatchewan Agriculture and Food) and the herbicide label for information on crop tolerances to residues.

Seed Placement

Deep seed placement is the most common cause of failure in forage stand establishment. " An emergent seedling is dependent on the food reserves in the seed for growth until green leaves develop...". Because most forage seeds are small they do not contain sufficient food reserves in the seed to support growth from deep within the soil (Forage manual, Alberta Agriculture). In general, the smaller the seed, the more critical is shallow seed placement.

Optimum Seeding Depth

Optimum seeding depth for most forages is 1 to 2 cm (0.5 to 0.75 inches). On heavy soils the best results can be obtained by seeding close to 1 cm as possible. On more lightly textured soils, the depth may be increased slightly but should not exceed 3 cm (see table 1). Do not seed more deeply in an attempt to " seed to moisture".

Source: Agriculture Canada Research Station, Swift Current

The seed row should be packed after seeding to ensure good contact between the seed and firm, moist soil.

SEEDING DATE

Seed when you have the highest probability of good soil moisture following seeding.

Early spring seeding, to take advantage of good soil moisture, is most likely to produce the best establishment. The later the seeding date, the greater the risk of failure due to drought, high temperatures and competition from weeds. If moisture conditions are good, spring seeding may be slightly delayed for better pre-seeding weed control.

Late fall seeding, allowing the seed to lie dominant through the winter and geminate in the early spring, is a suitable alternative for most forages except sweetclover. Seed after October 15 or after night temperatures drop below freezing. Do not seed sweetclover after August 1 as it may winterkill.

If moisture is abundant, grasses can be successfully estate. fished by seeding around August 15. Legumes, especially alfalfa and sweetclover, should not be seeded at this time because of the risk of winterkill.

SEEDING EQUIPMENT

Forages may be seeded with a wide variety of equipment. Equipment must perform three basic functions: seed metering; seed placement; and seed packing.

SEED METERING

The equipment must be able to meter the required amount of seed accurately.

Seed boxes specially designed for metering fine seeds and large, fluffy seeds are easiest to use. Boxes used for seeding grains, including air seeders, can also be used. Modifications such as agitators may be required to prevent bridging. Some fertilizer metering boxes can also be used for seeding forage.

Mixing seed with fertilizer or other material will increase density and volume and help to ensure a uniform flow through the metering cups or rolls. Premix only enough seed for a day or two. If mixing with fertilizer, use a phosphate formulation such as 11-55-0 at a maximum of 15 pounds per acre. Fertilizer should not be mixed with inoculated legume seed as it may destroy the innoculum. Cracked grain or horticultural vermiculite are other suitable mixing materials.

Some specialized seeders have adjustable row spacings and independent metering for grass and legumes. On conventional equipment, you can achieve the same effect by blocking seed runs and fabricating seed box dividers.

Calibrate the machine carefully to ensure proper seeding rate. Check the seeding rate by using the "Bulk Weight of Seed" or the "Seeds Per Foot of Row" calibration method described in the "Calibrating Seeding Equipment' section.

REQUIREMENTS FOR SEED PLACEMENT

To place the seed at a shallow, uniform depth in contact with the soil, the seeder opener must penetrate surface residue and the soil to the required depth. There must be a method of controlling the depth of penetration. Proper seed placement is easier when seeding into a firm, moist seedbed.

Various types of seed openers can be used:

1. DISC OPENERS are excellent for fields with little surface residue, such as summerfaliow or light crop stubble. Depth control bands on the discs will help to ensure proper seed placement, especially in soft fields (see illustration of depth bands on disc openers, above). Some models may not be able to penetrate dry, unworked soil.
2. HOE TYPE OPENERS can be used in a wide range of conditions. Soil penetration is good. Unless the machine provides individual row depth control, maintaining consistent seeding depth may be difficult in some conditions. Hoe openers have superior ability to penetrate residue cover, provided the shank arrangement allows trash clearance.
3. DISCERS AND CULTIVATORS WITH SWEEPS are seldom suitable for seeding forage; it is difficult to maintain a uniform, shallow seeding depth.
4. GRANULAR APPLICATORS are sometimes used to broadcast seed on tilled soil. The seed can then be lightly incorporated by harrowing and packing.

COULTERS will improve penetration of both disc and hoe type openers through heavy residue and firm soil.

Packing

After seeding, pack the soil to ensure good soil to seed contact. Equipment that packs each row (press wheels) will produce the best results with the least chance that weeds will grow between the rows.

Refer to SEEDING EQUIPMENT FOR FORAGES (Saskatchewan Agriculture and Food) for more information on seeding equipment and calibration methods.

Seeding Rate

Determine the rate of seeding (kg/ha or lbs/acre) taking into account the species being sown, pure live seed (PLS) content of the seed stock, soil and climatic zone (FIGURE 2), and row spacing. Tables 3A & 3B give the recommended rates of seeding for forages for dryland hay and pasture in the different soil zones.

NOTE: When seeding grass alone for pasture in the brown and dark-brown soil zones, increase grass recommended rate by 1.5 x.

PLANT CERTIFIED SEED

Where possible, producers are advised to plant only certified forage seed because of the guaranteed germination and purity. If there is a question on the quality of your seed, request to have a copy of the seed analysis report. For seed of low quality or high dormancy, adjust the bulk seeding rate by using the PLS (pure live seed) index. The formula for this adjustment follows:

Recommended seeding rate
( % actual gemmination/100) X (% actual purity/100)
= adjusted seeding rate

CALIBRATE THE SEEDING EQUIPMENT

The seeding equipment must be adjusted to meter the required amount of seed as the seeder passes over the field. Two methods may be used:

1. Calibration by Bulk Weight of Seed.
2. Calibration by Number of Seeds per Foot of Row.

CALIBRATION BY BULK WEIGHT OF SEED

Weigh the seed metered out for a fraction of an acre and then calculate the rate per acre. The following procedure is based on 1 /50th of an acre.

1. Determine the row spacing of the seeder.
2. Determine the circumference of the wheel (distance travelled per revolution) that drives the metering melanism on the seeder.
3. Jack the drill up so this wheel clears the ground and turns freely.
4. Place a quantity of seed over a number of seed cups in the drill box; turn the drive wheel until the seed is flowing uniformly from the cups covered with seed.
5. Randomly select six drill runs metering seed and set up containers or bags to collect the seed metered by these runs.
6. Calculate the number of drive wheel revolutions necessary to calibrate the drill according to Table 4.
7. Rotate the drive wheel the required number of revolutions as determined in step 6; collect the seed metered out in the containers as set up in step 5.
8. Weigh the total amount of seed (in ounces) collected in the containers set up in step 5.
9. Calculate the seeding rate using the following formula:
   weight of seed collected (in ounces) X 50 /16= pounds per acre
10. Adjust seeding rate and repeat steps 7 to 9 until the desired rate is achieved.

EXAMPLE

You are using a seeder with 7inch row spacings. The circumference of the meter drive wheel is 9.5 feet. By using Table 4 you determine that the number of drive-wheel revolutions required to calibrate a drill with 7 inch row spacings (249 divided by 9.5) is 26. Rotate the drive wheel 26 sums. Weight of the seed collected from the six runs is 3 ounces. The seeding rate is

3 X 50/ 16 = 9.40 lbs/acre

Note: This is but one of many formulae for calculating seeding rate by bulk seed weight. The operator's manual for your seeder, or other reference material at hand, may have other equally effective methods of calibrating your equipment.

CALIBRATION BY COUNTING SEEDS PER FOOT OF SEED ROW

Most recommended seeding rates are given in pounds per acre (see tables 3A & 3B). Each forage species has an approximate number of seeds per pound (see table 5). You can calibrate the seeding rate can by determining the number of seeds required per foot of drill row to achieve the desired seeding rate and adjusting the machine to meter out this number of seeds per foot of drill row.

Follow these steps to calibrate the drill using this method:

1. Determine the desired seeding rate per acre from Table 3A & 3B.
2. Using Table 5, determine the number of seeds required per square foot to achieve the desired rate.
3. Determine the row spacing of the seeding machine being used.
4. From Table 6 determine the number of seeds per foot of row required to achieve the desired seeding rate at the given row spacing.
5. Fill the drill box, run the drill and check to see that all the drill runs are metering uniformly.
6. Run the drill for a short distance over a hard surface such as a road, tarpaulin plywood.
7. Count the number of seeds per foot of drill row in several drill rows.
8. Adjust and repeat steps 6 & 7 until the desired rate is achieved.

EXAMPLE

A mixture of crested wheatgrass and alfalfa is to be seeded at a rate of 5 & 2 lbs/acre respectively. Drill row spacing is 8".

From TABLE 5 determine the number of seeds required per square foot to achieve these rates:

Crested wheatgrass 5 lbs X 4 seeds/lbs/acre = 20

Alfalfa 2 lbs X 4.6 seeds/lbs/acre = 9

Total = 29

From TABLE 6 it is determined that, to average 29 seeds per square foot, approximately 20 seeds are required per foot of drill row at 8 inch spacings.

ROW SPACING AND SEEDING PATTERN

Row spacing can affect productivity over the long term. Wider rows minimize competition for moisture between plants and increase production when moisture is deficient. But rows spaced too widely provide poor ground cover, particularly under heavy grazing, and can result in severe weed infestations between rows and increased potential for erosion.

What row spacing should you use? Consider the soil zone, soil texture and purpose of the stand. Use Table 7 as a guide to row spacing.

Seeding alfalfa in alternate rows, or cross seeding, will help to maintain more alfalfa in the stand than when the two forages are seeded in the same row. This may provide slightly higher yields and quality of forage. But ground cover is reduced by alternate row seeding, increasing the potential for erosion.

LEGUME INOCULATION

Legumes team up with bacteria called RHIZOBIA to "fix" free nitrogen from the air. This fixation leads to higher yields and accumulates nitrogen in the soil for future crop production.

To maximize N fixation, the seed must be "inoculated", or coated with an appropriate strain of RHIZOBIUM, at the time of planting. As the seed germinates the bacteria infect the plant through the root hairs and become established in nodules on the plant roots.

When inoculating legumes, remember:

1. Rhizobium strains are species specific; i.e., pea inoculant is ineffective on alfalfa and vice versa. Be sure to use the proper strain.
2. The inoculant is a live culture with a limited shelf life. Check expiry date on bag and do not use outdated product. The inoculant is sensitive to sunlight and heat. Store in a cool, dark place. Refrigerate if storing for extended period of time. Do not freeze.
3. Ensure that the inoculant "sticks" to the seed.
   1. Purchase inoculant with commercially prepared "sticker" ready to mix with the seed or prepare your own "sticker" using a 10% solution of corn syrup, milk powder, or honey.
   2. Wet the seed down and then add the inoculant slowly as the seed is being mixed.
4. Ensure that the seed is thoroughly coated. Mix with a shovel, cement mixer or mix mill, depending on the quantity being inoculated.
5. As an alternative, have your seed supplier pre-inoculate the seed shortly before seeding.
6. Avoid using seed treatments that may be toxic to the inoculant.
7. Do not mix inoculated seed directly with phosphate fertilizer; high concentrations of fertilizer salts may kill the RHIZOBIA.
8. If seeding is delayed, store the seed in a cool, dark place; the RHIZOBIA will remain viable for 3-4 days. If seeding is delayed longer than that, the seed should be reinoculated.

Field check for rhizobia activity

Check to see if the legumes are fixing nitrogen by examining the roots in mid-summer. Dig up a few plants and gently shake the soil away from the roots. Numerous small, swollen nodules on the roots should be visible. The inside of the nodule should be pink.

For more detailed information, please refer to FARM FACTS: LEGUME INOCULATION (Saskatchewan Agriculture and Food and Saskatchewan Rural Development).

COMPANION CROPS

Companion crops compete with forage seedlings for moisture, light and nutrients. This competition reduces the vigour and increases the mortality rate of forage seedlings, resulting in lower yields in the year following establishment, and sometimes for several years thereafter. Companion crops are not recommended in the brown soil zone.

On the other hand, a companion crop can provide some production from the field in the year of establishment, suppress weeds, and protect the seedlings from heat, wind and water action.

Should you seed a companion crop? Consider soil moisture, soil type, erosion potential, climatic zone, seedling vigour, and the value of immediate production versus longer term forage yield losses.

If you use a companion crop, manage it to minimize competition with forage seedlings.

1. Select the least competitive companion crop: flax, oats, wheat, barley, canola in that order.
2. Seed the companion crop at a reduced rate: one-quarter to one half the normal rate.
3. Seed the companion crop in rows at right angles to the forage seed rows or in alternate rows to the forage.
4. Remove the companion crop as early as possible after heading, preferably as hay or silage. If the crop is to be harvested for grain, use an early maturing variety and harvest as soon as ready. Bale and remove or chop and spread the straw and spread the chaff. Forage seedlings are easily smothered by a cover of straw or chaff.
5. Cut the companion crop to leave a tall stubble (6 to 8 inches) to provide protection to the seedlings and trap snow.

In using a companion crop, strive to provide a good environment for the forage seedlings, not to produce a "bumper" companion crop.

WEED CONTROL

Weeds compete with forage seedlings for moisture, light and nutrients and should be controlled to promote strong forage establishment. Investing in weed control in the establishment year can reduce problems in later years.

Perennial weeds, particularly those which cannot be controlled "in crop" with herbicides, should be brought under control in annual crop rotations before planting the forage.

Mowing is the most common method of weed control in a seedling forage stand. Mowing removes competition and prevents the weeds from producing seed. Timing is important. If weed growth is heavy remove it from the field by salvaging it for silage or hay.

Mowing does not effectively control green foxtail (wild millet), which is very competitive with forage seedlings, particularly grass. If the infestation is severe, control it with an appropriate herbicide.

A variety of herbicides is available for controlling weeds in forages. Refer to WEED CONTROL IN FIELD CROPS AND FORAGES for infommation on selection, weeds controlled, rates and timing of herbicide application. The degree to which you want a "weed-free" stand will determine whether the expense of herbicides is warranted.

Once well-established, forages are highly competitive and will compete with most weeds if managed properly.

INSECTS

Grasshoppers can quickly wipe out an emerging forage stand. Vigilance in detection and prompt control measures are the keys to crop protection.

Examine sweetclover fields until the plants are well established, since the sweetclover weevil may attack and destroy very young seedlings.

For insect control recommendations, refer to the Saskatchewan Agriculture and Food publications INSECT CONTROL IN FIELD CROPS and GRASSHOPPER CONTROL.

SEEDING SALINE AREAS

The accumulation of salts in some soils can restrict plant growth and make it difficult to establish a forage stand.

There are two keys to success:

1. Select species that are tolerant of salinity.
2. Seed when salt concentrations are at their lowest.

Salt concentrations vary considerably from one area of a field to another. Select a mixture of species with a broad range of salt tolerance to achieve the best cover and productivity.

TABLE 8A lists forage mixtures recommended for soils affected by different levels of salinity and flooding. Measure salinity levels in the field with a conductivity meter (EM38), or have soil samples analyzed by a soil testing laboratory. EM38s may be available for loan from Saskatchewan Rural Service Centres or PFRA Area Conservationists.

TABLE 8B Native Seed Mixture for Saline Soils (lbs/ac or kg/ha)

Salt concentrations at the soil surface develop when water moves up, bonging the salt with it, and then evaporates from the surface.

Continuous cropping using salt tolerant crops such as barley, and maintaining a residue cover on the surface, will help to minimize this concentration. Snow melt and rainfall will temporarily dilute and leach salts out of the surface soil layer.

Seeding shallowly in late fall into standing stubble allows the seed to lie dominant over winter and germinate in early spring when salt concentrations are low. This increases the probability of successful establishment.

In general, crops on saline land require higher amounts of phosphorous for root development. Saline soils are high in nitrates; however, some supplemental nitrogen applied at time of seeding may be helpful in achieving successful establishment. Potassium and sulphur are not required.

Failures in forage establishment on saline soils are not uncommon. Repeated attempts may be required to achieve a satisfactory stand. For more information on establishing forage on saline soils, refer to THE NATURE AND MANAGEMENT OF SALTAFFECTED LAND IN SASKATCHEWAN (Saskatchewan Agriculture and Food.)

EVALUATION

Forages, particularly grasses, develop and establish slowly. Producers should not be too hasty in writing off a field.

Four to six weeks after germination, evaluate fields planted in late fall and spring. Evaluate initial density and distribution during this inspection. Note weed and insect problems and take appropriate action. Inspect fields a second time in the summer and/or the following spring. Early fall plantings cannot be accurately evaluated until the following year. Examine sweetclover two to four weeks after seeding, since the sweetclover weevil may attack and destroy very young seedlings.

Use a consistent representative random sampling technique to get an objective evaluation of the entire field. Generally, three to four forage plants per square foot will pro" vice an adequate stand. This will vary with management objectives and forage species in the mixture.

Consider not only the density of the stand, but also the health and vigour of the seedlings. A grass seedling should have a permanent root system developing. Some tillering or rhizome development should be evident in well established plants. Alfalfa should have a well-developed tap root, with secondary and tertiary roots and a well-developed crown set below the soil surface.

Why Do Forage Seedings Fail?

A partial guide to forage establishment problems.

Many of the forage seeds you plant will not survive. To compensate, plant more seeds than the number of plants you require for a mature, productive stand. Losses can occur any time, from germination to maturity. If losses are excessive at any stage, establishment may fail. Why do some plants live while others die?

1. SEEDS MAY FAIL TO GERMINATE
   1. Seed is not viable.
   2. Seed is dominant.
   3. Insufficient air seed sown deeply in wet, heavy soil may lack oxygen to geminate.
   4. Inadequate moisture and/or temperature for germination alternating temperature and moisture levels can lower seed viability and result in death.
2. SEEDLINGS MAY DIE AFTER GERMINATION
   1. Loose seedbed seed in loose, dry soil may geminate after a light rain but dry out and die before developing a supporting root system.
   2. Seed too deep and unable to emerge.
   3. Soil baked and crusted; emerging seedlings cannot penetrate it.
   4. Toxicity in the soil herbicide residues, fertilizer concentrations.
3. SEEDLINGS MAY DIE AFTER ESTABLISHMENT
   1. Drought insufficient moisture to sustain growth.
   2. Competition for moisture and nutrients from companion crops and weeds.
   3. Grasshopper damage.
   4. Winter kill seedlings insufficiently developed to withstand winter temperatures.
   5. Flooding and/or inadequate drainage.
   6. Species not adapted to conditions saline soil, acidic soil, winter hardiness, drought tolerance.
   7. Low soil fertility.
   8. Diseases.

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