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V. Improvement of Legume Seedling Vigor
LEGUME SEEDLING GROWTH
to excessive soil compaction (Tesar and Jackobs, 1972). Firming is best accomplished by rolling with a heavy roller or by cultipacking. If the needed equipment is not available for this, a weighted spike harrow or an irrigation float or
leveler will compact the soil before seeding.
VII. Seeding Forage Legumes
A. SEED TREATMENT
Before seeding, legume seed should be inoculated with symbiotic bacteria
(Rhizobium spp .).
The symbiotic bacteria are specific for many legumes such as birdsfoot trefoil
and sainfoin but in some cases bacteria will cross-inoculate with several species.
Inoculation is essential when a legume is seeded in an area for the first time, For
successful legume inoculation the following procedures should be adhered to:
1. Select the proper inoculant for the legume t o be grown.
2. Store the commercial culture in a cool, dark place until it will be used.
3. Plant seed within 48 hours after inoculation, or reinoculate.
4. Inoculate in all cases of doubt, and always inoculate on new land.
Small amounts of seed and inoculant may be mixed in a tub or bucket. Larger
amounts may be mixed in a small concrete mixer or by hand on a cement floor
or on the bottom of a truck bed. Addition of sticking agents such as milk or
diluted syrup will help inoculant adhere to seed, Most companies that sell
inoculant also sell sticking agents.
B. CALCULATION OF SEEDING RATES
Seeding rates are recommended to provide a given number of viable seeds per
linear meter of drill row. The percentage of viable seed in a seed lot is calculated
by multiplying germination percentage by purity percentage and dividing by
100. The value obtained is called pure live seed index (PLS). Thus if a seed lot
has a percentage germination and purity of 90 and 85, respectively, the PLS is
90 X SS/lOO = 76.5%. For legumes, the percentage of hard seed is added to the
germination percentage before multiplying it by the purity percentage.
The number of seeds planted per meter of row is dependent upon the number
of seeds per kilogram, the kilograms of seed planted per hectare (ha) and row
spacing. It may be computed as follows:
seed per meter of
= Number of PLS/kg X planting rate in Kg PLS/ha
row m in ha at width to be planted
C . S . COOPER
Thus if a species contains 220,000 PLS/kg, and a planting rate of 6 kg PLS/ha
is desired with 15-cm row spacing, viable seed per linear meter of row would be:
19.8 viable seeds per row meter
The number of seeds that would be seeded per meter of row with a seeding
rate of 1 kg/ha and with several row spacings is shown for some common forage
legumes in Table I. These values are based on seeds per kilogram for nontested
seed lots. To obtain viable seed, multiply values given by 100 and divide by the
percent PLS of the seed lot to be planted.
If one desires to seed a given number of viable seeds per linear meter, he can
calculate seeding rate. For example, if 60 viable seed per meter of row is desired
in 30-cm rows and the seed lot contains 220,000 PLS/kg, computation of
seeding rate of PLS/ha would be:
Planting rate in kg PLS =
Number of viable seed desired per row m X row m/ha
Number of PLS kg
Planting rate in kg PLS/ha = 6o 33’333 = 9.1 @/ha
The numbers of row meter per hectare for different row spacings are as
Row spacing (cm)
Row meter per hectare
Seeding rates for forage legumes vary from region to region and within regions
depending upon seeding site condition. More seeds are sown than number of
plants needed. In humid regions 70% emergence is considered excellent with
good seeding techniques (Tesar and Jackobs, 1972) and the seedlings surviving
the first year are 40 to 50% of the seed sown. A seeding rate of 11.2 kg/ha which
was reported as average for the humid northeastern states in 1962 gave 538 seeds
per square meter. From this seed 215 to 269 plants per square meter survived
the first year. Jackobs and Miller (1970) have shown that this number will give
maximum yield in the first harvest year in Illinois. They also report that 60 to
78 plants per square meter is adequate for maximum yield in subsequent years.
In Montana 7.8 kg/ha of alfalfa provides adequate stands under irrigation.
LEGUME SEEDLING GROWTH
Seed per Meter of Row for Some Common Forage Legumes Seeded at a Seeding Rate of
1 Kg/Ha at Different Row Spacings
Row spacing in cm
Astragalus cicer L.
Coronilla varia L.
Lespedeza cuneata Don.
Lespedeza stipulacea Maxim.
Lespedeza striata Hook Lk Am.
Medicago sativa L.
Melilotus alba Desr.
Melilotus officinalis Lam.
Lotus cornidatus ..I
Onobrychis viciifolia Scop.
Trifolium fragiferum L.
Trifoliurn hybridum L.
Trifolium pratense L.
Trifolium repens L.
Trifolium subterraneum L.
Vicia sativa L.
Cicer milk vetch
4 4 1,472 6.6
White sweet clover
Yellow sweet clover
8.4 16.8 25.3
7.3 14.5 21.6
23.2 46.3 69.6
14.9 29.8 44.4
12.6 25.2 37.8
13.2 26.5 39.6
17.2 34.4 51.6
17.2 34.4 51.6
24.8 49.6 74.4
19.9 39.7 59.4
46.4 92.7 139.2
18.2 36.4 54.6
53.0 105.9 158.4
C. DRILL CALIBRATION
Dnlls may be calibrated by weighlng the seed delivered over a given area or by
converting kilograms of seed per hectare to number of seeds per row meter and
then counting the number of seeds delivered per meter of row. The latter
method is the easiest. Run the drill over hard ground or a canvas tarp and count
the seed per meter of row. Adjust drill setting until desired number is obtained.
Table I gives the number of seed per meter of row of a number of legumes at a 1
kg/ha seeding rate and at different row spacings. To obtain number of seeds per
row meter multiply number of kilograms of PLS to be seeded by the value given
for the row spacing to be used. For example, at a 10-kg PLS rate of seeding for
alfalfa seeded in 15-cm row spacing, 66 seeds should be seeded per meter of row.
For calibrating drills for seeding mixtures, mix the grass and legume in proper
proportion and then count the number of seed of the legume per meter. Grass
seed will automatically be seeded in the right proportion.
Legumes and grasses establish best when seeded in alternate rows where they
don’t compete against each other in early stages of development. Blocking off
every other feed in the grain box for grass seed and alternate feeds in the legume
box is an easy method of alternate row seedings. One-half-kilogram cloth bags
filed with sand effectively block feeds.
C. S. COOPER
Forage legume seed may be broadcast or drilled. Broadcast seedings are seldom
successful in the arid regions of the West but sometimes are successful in humid
areas. Best results are obtained if seed is broadcast in early spring when the soil
surface is cracked from freezing and thawing. Broadcast seed should be covered
by harrowing lightly.
Cultipacker seeders are used extensively for legume seedings. They consist of
two corrugated rollers. The first roller firms the soil and leaves a small groove up
to 2.5 cm deep. Seed, metered from a drill box, is broadcast into the grooves.
The second roller covers the seed and firms the soil around it.
Grain drills with a legume seed box do an excellent job of seeding, provided
that the seedbed is firm and/or depth bands are used. Depth bands can be made
locally or purchased from equipment dealers.
The single disk drill is excellent for seeding hard and brushy seedbeds. Double
disk drills are better on stubble or well-prepared seedbeds. Deep furrow drills
place the seed in the bottom of a furrow, but it is covered at the normal seeding
depth. These drills are effective in arid regions where snow and rainfall tend to
concentrate in the bottom of the furrow. A danger of deep furrow planting is
that in loose or erodable soils the furrows may fill in and cover the seed too
The most reliable seeding method, where soil fertility is a problem, is band
seeding. With this method, special drills place fertilizer in a band 3-6 cm deep.
Seed is then drilled directly over the fertilizer band at a depth of 0.5 to 1.5 cm
and the soil is firmed over the seed with press wheels. Press wheels are an asset to
any drill when seeding legumes.
E. SOD SEEDING
Sod seeding has increased with the improvement of seeding equipment and the
development of herbicides to control competition. Seeding success with no-till
equipment is dependent upon: (1) reduction of competition, ( 2 ) slicing the sod
for seed placement, (3) placement of seed at the proper depth, (4) firming soil
over the seed, and ( 5 ) adequate moisture and fertility for good germination and
growth. In Maryland, an offset concave disk placed between the leading straight
coulter and spearpoint opener of a commercial grassland drill has consistently
given good stands of birdsfoot trefoil and crown vetch. Deere and Co. is
marketing a Power-Till seeder developed by the University of Kentucky (Ackley,
1975). This machine has sawlike cutter wheels which cut through surface residue
and existing sod to open up a precise seed slot in the soil surface. Cutter wheels
Seeding and Seeding Year Management Chart'
(1) Prior to seeding
Prior to seeding
Select quality seed of
To help insure good stands of adapted
recommended varieties free
Inoculate legume seed with proper To provide symbiotic bacteria for
bacteria, if needed
Prior to seeding
Level field if gravity irrigation is
to be used
Prepare a firm seedbed
Prior to seeding
Provide adequate fertility
Prior to seeding
(2) At seeding
Seed at recommended depth
(3) Immediately after seeding Frequent observation to note soil
crusting prior to emergence; if
crusting occurs, go over land
with light cultipacker
To insure uniform distribution of
To bring seed in close contact with
moisture and nutrients; prolongs
moisture retention for germination;
to help control depth of seeding
To stimulate development, decrease
Pastures with highly adapted
species; weed control
Production of nitrogen by
legumes for use by grass;
increased productivity; cheap
source of nitrogen
Good uniform stands; rapid
Good stands and maximum
To allow seed to emerge with energy
Uniform emergence and good
To break up soil crust to allow
Better emergence and stands
TABLE I1 (continued)
(4) Dunng establishment
Frequent check of soil moisture; if To provide adequate water for seedling Rapid seedling development;
dry, apply enough water to wet
seedling root zone
To increase photosynthetic activity of Vigorous seedlings, good stands;
Frequent observation of weed
higher yields in fust and
competition; if weed competition seedlings
strong, mow with guards set high or
subsequent production years
spray with proper herbicide
(5) Do not seed with companion crop in close row spacing; if used, space companion crop in 18- to 21-inch Less competition to forage
rows. Use the same drill setting as normal for companion crop but plug 1/2 or 2/3 of spouts to obtain
seedlings; increases chances for
seeding success; increases forage
(6) Avoid grazing until late fall of seeding year.
Better establishment. Less winter
injury; more productive stands
(7) Gear all management operations to meet needs of the forage seeding.
‘After Cooper et QL (1973).
LEGUME SEEDLING GROWTH
rotate in the direction of travel at 730 rpm, leave a slot 1.3 to 2.0 cm wide, and
deposit loose soil in the slot. Seed is metered into the seed slot and firmed with
packer wheels. A sprayer attachment then sprays a narrow band of herbicide,
approximately 10 cm wide over the slot area to retard plant competition until
seedlings have sufficient growth t o be competitive.
V I I I . Seeding Management Practices
Once legumes are seeded, periodic checking of the new seeding can pay
dividends. Soil crusts that form before emergence may be broken up with a light
cultipacker. Weed competition following emergence may be controlled with
chemicals such as 2-4-D-B or by clipping just above the young seedling. Management practices for seeding and establishing a new legume seeding are presented
in Table 11. Close adherence to these management principles will greatly increase
the chances of seeding success.
Aside from improving the vigor of legume seedlings, improvement of establishment practices is the major means of increasing seeding success. The often
recommended firm seedbed needed for good establishment is seldom obtained in
farm practice. Likewise, depth regulator bands which insure placement of seed at
desired depth are too seldom used. There is a major need for seeding equipment
designed specifically for seeding grasses and legumes. This equipment should
insure the placement of the seed at the proper depth in a firm seedbed. It should
also provide for simultaneous seeding of two species in alternate rows at
different depths and should provide for band placement of fertilizer below seed.
Proper application of the present state of knowledge concerning growth of
the legume seedling should obtain successful establishment of legumes.
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YIELDS AND CULTURAL ENERGY REQUIREMENTS
FOR CORN AND SOYBEANS
WITH VARIOUS TILLAGE-PLANTING SYSTEMS
C B Richey. D R Griffith. and S D Parsons
Purdue Agricultural Experiment Station. Lafayette. Indiana
I1. Tillage-Planting Systems . . . . . . . . . . . . . . . . . .
A . Definition of Tillage-Planting System ............................
B. High-Energy Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C. Moderate-Energy Systems ......................................
D Low-Energy Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
111. Influence of Tillage-Planting System on Yields ........................
A Corn ......................................................
B. Soybeans ..................................................
IV. Yield Factors Influenced by Tillage-Planting System ....................
A . Early Planting ...............................................
B . Soil Compaction .............................................
C. Weed Control ...............................................
D . Fertilizer Placement ..........................................
E . Moisture Conservation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
F . Soil Erosion Prevention .......................................
G . Insect and Disease Control .....................................
V. Energy Requirements for Various Tillage-Planting Systems . . . . . . . . . . . . . .
A . Operations in Low-, Medium-, and High-Draft Soils ..................
B . Various Tillage-Planting Systems in Low-, Medium., and High-Draft Soils .
C. Corn Tillage Savings ..........................................
D . SoybeanTillage Savings .......................................
VI . Projecting Energy Savings with Reduced Tillage .......................
VII . Conclusions ...................................................
Tradition has it that the Pilgrims were introduced to corn by the Indians.The
Indians used a low-energy tillage-planting system wherein they dug a hole.
dropped in a fish for fertilizer. and then planted a hill of corn .
As plows and mechanical planters became available. farmers were able to
substitute animal power for manual labor and thus multiply their output per