Extension Circular 61-135: This circular contains information about determining methods for using Pure Live Seeds. It includes information on calculating mixtures on a PLS basis, Planning seedlings, native harvested mixtures of grasses, and determining the cost of PLS

Burzlaff, D. F.

Swinbank, J. C.

English

DigitalCommons@University of Nebraska

University of Nebraska - LincolnDigitalCommons@University of Nebraska - LincolnHistorical Materials from University of Nebraska-Lincoln Extension Extension1961EC61-135 Pure Live Seed Method forDetermining Requirements for Grass Seedings...D. F. BurzlaffJ. C. SwinbankFollow this and additional works at: http://digitalcommons.unl.edu/extensionhistThis Article is brought to you for free and open access by the Extension at DigitalCommons@University of Nebraska - Lincoln. It has been accepted forinclusion in Historical Materials from University of Nebraska-Lincoln Extension by an authorized administrator of DigitalCommons@University ofNebraska - Lincoln.Burzlaff, D. F. and Swinbank, J. C., "EC61-135 Pure Live Seed Method for Determining Requirements for Grass Seedings..." (1961).Historical Materials from University of Nebraska-Lincoln Extension. 3515.http://digitalcommons.unl.edu/extensionhist/3515~ AGICI s 8S -..9. f-7 \-\- (ol-135" cl lt\ /~ E.G. 61-135 ,~ <;::) ~ :'<f ~ ~ J ~ <"\./ ("..) ~ t'-' ~ .~ '0"' <, <' ,· ~ <::::) •• ) <!.J ......... <i .. ? ~ ~ ~ URE ~~ C:f'\ ~ .... .>.~ IVE > EED METHOD FOR DETERMINING REQUIREMENTS FOR GRASS SEEDINGS ....... . EXTENSION SERVICE UNIVERSITY OF NEBRASKA COLLEGE OF AGRICULTURE AND U . S . DEPARTMENT OF AGRICULTURE COOPERATING E . F. FROLIK. DEAN E . W . JANIKE, DIRECTOR PURE LIVE SEED CPLS) METHOD FOR DETERMINING REQIREMENTS FOR GRASS SEEDINGS D. F. Burzlaff and J. C . SwinbankJ/ The "Pure Live Seed" Method Grass seed lots may vary widely in quality and price. Some lots of seed--especially native grasses--contain inert material, undesirable mixtures, weed seeds, and grass seeds that will not grow. Since only live seeds of the desired crop are of value, the pure live seed way is the business-like way to buy, plant and sell grass seed. It assures farmers and ranchers of full value for their seed dollar and protects producers and handlers of high quality seed against price penalties experienced in competition with low quality seed priced without regard to purity and germination. Pure live seed planting rates supply the desired number of live seeds per acre and better stands can be expected. The term "pure live seed" (PLS) refers to the amount of live seed of the desired crop which is present in any lot of seed material. The percentage of pure live seed present is determined by multiplying the purity times the germination. Seed, if properly labeled, will have information attached to show the purity, germination, weed seeds, hard seeds, other crop seed, and inert matter. Thus, the seed tag supplies the information needed to plan seeding mixtures on a pure live seed basis. Calculating Mixtures on a PLS Basis Calculating mixtures for grass seedings need not be difficult or confusing. Actu-ally, this is not different from determining the amount of crude protein in a 100-pound bag of 40% protein supplement. Similar calculations are performed each time you decide how many pounds of a 45% fertilizer are needed to apply 100 pounds of the needed ele-ment. This circular has been prepared to acquaint you with the procedure for making grass-seeding calculations on the basis of pure live seed content. Each County Extension Office, in cooperation with the Soil Conservation Service and the County ASC Committee, should develop basic mixtures of desirable grasses for each site in the county. An example of a set of mixtures and rates of seeding is pre-sented in Table 1. These seeding rates are determined on the basis of approximately 20 live seeds per square foot. Any grass included in a mixture should be adapted to the soils and climate of the area. Table 2 shows many of the grasses recommended for seeding in Nebraska. The areas of the state in which each grass is adapted for production are indicated. Table 2 shows the approximate number of pounds of PLS of each grass that must be seeded to assure at least 20 live seeds per square foot. This information is used in determining the amount of each species to be included in the mixture. J/ Specialists in Range Management and Agronomy respectively, University of Nebraska Agricultural Extension Service. 3 • To see hOW' mixtures are formulated refer to Table 1. Here is an example from Table 1 of the first choice mixture for hardland sites in Sherman County: Species Little bluestem Side-oats grama Western wheatgrass Switchgrass % ofMixture 30 20 20 30 Lbs . PLS Per Acre 1.1 1.0 1.6 1.0 4.7 The percentage figures represent the amount of each grass in the mixture. The amount of each species included depends upon what composition is desired in the forage to be produced. If legumes are included I they usually do not represent more than 20 percent of a forage mixture. The pounds of PLS per acre are determined by multiplying the percentage figure for each species by the number of pounds of PLS required to make a full seeding (Table 2) . In the above example: Little bluestem Side-oats grama Western wheatgrass Switchgrass 30% 20% 20% 30% Planning Seedings on a PLS Basis X X X X 3.5 = 4.5 = 8.0 . = 3.0 = 1 . 0 5 or 1 . 1 * lbs . PLS per acre . 90 lb. or 1 . 0 * lb. PLS per acre 1 . 6 lbs . PLS per acre .90 lb. or 1.0* lb. PLS per acre When planning a grass seeding 1 first consider the purpose of the seeding and the site on which it is to be made. Then select the proper mixture from the list of grass seeding mixtures developed for your county. Let us assume 1 for example I that you desire to make a seeding on 40 acres of land. After some consideration you select the follOW'ing basic mixture: Species Little bluestem Side-oats grama Blue grama Western wheatgrass Percent of Each Species In Mixture SO% 25% 15% 10% Pounds PLS Per Acre 1.8 1.2 . 3 .8 *When computing seeding rates, always remember to increase any fractional value to the next highest tenth of a pound. 4 To determine the amount of PLS required for the seeding 1 multiply the number of acres to be seeded times the pounds of PLS required per acre for each species. This would give you the following information: Lbs. Acres Pounds PLS Grass Mixture PLS/Acre to be seeded to be purchased Little bluestem 50% 1.8 40 72 Side-oats grama 25% 1.2 40 48 Blue grama 15% . 3 40 12 Western wheatgrass 10% .8 40 32 Take this information to the seed dealer to determine the amount of bulk seed you . need to get the required amount of pure live seed. The amount is determined by applying the information on the seed tag to the information in Table 3 . For the example above assume the follow-ing seed quality: Species Little bluestem Side-oats grama Blue grama Western wheatgrass Purity 50% 40% 55% 80% Germination 60% 50% 60% 80% To determine the amount of little bluestem to purchase from seed of the above quality 1 find 11 5 0 11 in the column headed "purity. 11 Follow horizontally along this line to the column for the germination percentage of 60. At this point of intersection is found the number 3. 4. This means for every pound of PLS desired 1 3 . 4 pounds of rna terial must be purchased. For this seeding it would require 3. 4 x 72 I or approximately 2 45 pounds of little blue stem. This procedure is repeated for each species in the mixture 1 using their respective purity and germination values. The seed requirements for making your grass seeding would be: Little bluestem Side-oats grama Blue grama Western wheatgrass PLS and Native Harvested Mixtures of Grasses 245 pounds 240 pounds 37 pounds 52 pounds 574 pounds total What procedure must be follovved when a seeding is planned that consists of a native grass mixture? This mixture may be harvested mixture or a mixture made by the seed dealer. The components of the mixture with the purity and germination values for each must be known at the time the seeding is planned. This means there must be a seed analysis available on all locally harvested seed. 5 Assume in the above situation that little bluestem seed is not available except in a native harvested mixture. This mixture could be of the following analysis: Purity Germination PLS Little bluestem 35.6% 52% 18.5% Big bluestem 5.2% 51% 2.5% Side-oats grama 5.1% 60% 3.1% Inert and foreign rna tter 54.1% This analysis tells us that in each 100 pound bag of this mixture there are 18.5 pounds of little blue stem (PLS) I 2. 5 pounds of big bluestem (PLS) 1 and 3.1 pounds of s_ide-oats grama (PLS). Since big blues tern is adapted to this site I it may be substituted for some of the little blue stem in the mixture. In this case 21 pounds of big bluestem and little blue-stem (PLS) would be available in each 100 pounds of bulk material. The seeding called for 68 pounds PLS of little bluestem. Using the above mixture it would require 325 pounds of bulk material to provide this amount of pure live seed. In addition this 325 pounds would furnish 10 of the necessary 48 pounds PLS of side-oats grama. Determining the Cost of Pure Live Seed Traditionally I grass seed prices have been quoted on the bulk seed basis. However, because of widespread interest in the pure-live seed method many dealers are now quot-ing on a PLS basis. The cost of the pure live seed in any bulk seed lot can be determined by multiplying the purity times the germination and dividing the result into the bulk seed price. Here is the formula: Bulk Seed Price = Cost of Pure Live Seed Purity x Germination Example: Step l -- Substitute appropriate figures in the formula: Bulk Seed Price 75¢/lb. = Cost of PLS 50% (Purity) x 60% (Germination) Step 2 -- Determine the cost of PLS: $0.75 = .50 X .60 $0.75 .3000 = $2.50 for each pound of Pure Live Seed This formula provides a means of comparing the "actual" or "real" value of different lots of seed. The price per pound of pure live seed and not the bulk seed price deter-mines which seed lot is the better buy. 6 Farmers who buy grass seed on a pure live seed basis for the first time may be concerned because the price per pound of pure live seed is greater than .that of bulk seed. As the formula shows, the cost of the seed that will grow is no greater and in many cases may be less than that offered at a low bulk seed price. It should also be borne in mind that pure live seed planting rates are based on the amount of live seed needed to give the desired stand. Acknowledgment The authors express appreciation toE. C. Conard, Associate Professor of Agronomy, University of Nebraska, for helpful suggestions and other assistance in the preparation of this publication. 7 co 1st CHOICE Percent of PLS Table 1. (Example) Suggested Seeding Mixtures For Sherman County 2nd CHOICE Percent of PLS 3rd CHOICE Percent of SQecies Mixture Lbs/Acre Species Mixture Lbs/Acre Species Mixture Hardland Hard land Hard land Little bluestem 30 l.l Switchgrass 25 .8 Western Side-oats grama 20 l.O Big bluestem 25 1.5 wheatgrass 20 Western Indian grass 25 1.3 Intermediate wheatgrass 20 1.6 Side-oats grama 25 1.2 wheatgrass Switchgrass 30 l..:.Q 4.8 or 60 4.7 Bromegrass Alfalfa 20 Sandy land Sandy land Sandy land Sand bluestem 30 2.4 Switchgrass 50 1.5 Sand lovegrass 40 Switchgrass 30 l.O Sand lovegra s s 50 .5 I1;1termediate Prairie sandreed 20 . 7 2 .0 wheatgrass 40 Sand lovegrass 20 .2 Alfalfa 20 4.3 Wetland Wetland Wetland Big bluestem 25 1.5 Reed Tall wheatgrass 50 Indian grass 25 1.3 canarygrass 40 .8 Switchgrass 50 Switchgrass 30 l.O Bromegrass 40 2. 6 . Red clover 20 _J_ Redtop 20 _J_ 4.5 3.5 - --- --- - -PLS Lbs/Acre 1.6 6.0 3.9 . 8 6. 3 or 8. 4 . 6 4.0 . 8 5.4 5 .5 1.5 7.0 Table 2. Grasses commonly seeded for the establishment of permanent cover in Nebraska and recommended planting rates in terms of pure-live-seed. (Select a grass mixture which will result in about 20 live seeds per square foot--select column applicable to area of the state and the site condition.) Eastern .1/Required Pounds Central Western Pure-Live-Seed Per Eligible Acre (to plant ap-Grasses Hard- Sandy Wet Hard- Sandy Wet Hard-! Sandy Wet proximately 2 0 live and Legumes land land land seeds per sq. ft.) Bromegrass - - - - - - - 6.5 Tall fescue - - - - 4.0 Orchardgrass - - - - - 2.0 Intermediate wheatgrass - - - - - - 10.0 TaU wheatgrass - - - - - 11.0 Crested wheatgrass - - - - 5 .0 Russian wildrye - - 5 .0 Redtop - - - .4** Blue grarna - - - - - - 1.5 Side-oats grama - - - - - - 4.5 Buffalo grass - - 4.0* Sand bluestem - - - 8.0 Big bluestem - - - - - - - - 6.0 Little bluestem - - - - - - 3.5 Indian grass - - - - - - - - 5.0 Switchgrass - - - - - - - - 3.0 Sand lovegrass - - - - - 1.0 Prairie sandreed - - - 3.5 Green needlegrass - - - - 5.0 Slender wheatgrass - - 5 .5 Western wheatgrass - - - - - - - - 8.0 Canada wildrye - - - - - 7.5 Reed canarygra s s - - - - 2.0 Alfalfa - - - - - - - - 4.0 Sweet clover - - - - - - - - - 3.5 Red clover - - - - - 3.5 Alsike clover - - - 1.5 Birdsfoot trefoil - - - - - 2.5 Hairy vetch - - - - - 24.0*** Lespedeza - - 4.0 * Based on treated seed at the rate of approximately 4 pure live burs per square foot. ** Provides for approximately 40 pure live seeds per square foot. *** Provides for approximately 10 pure live seeds per square foot. .1/ A planting rate of 20 pure live seeds per square foot is considered adequate under good conditions of seedbed preparation and weather. Somewhat higher rates are suggested where obtaining a full, usable stand in a minimum time justifies the added cost. 9 Table 3. Pounds of Grass Seed Material Required to Yield One Pound of Pure Live Seed % : Percent Germination Purity : 100 : 95 : 90 : 85 : 80 : 75 : 70 : 65 : 60 : 55 : 50 : 45 : 40 : 35 : 30 : 25 : 20 15 : 10 100 95 90 85 80 75 70 65 ...... 60 o-55 . . 1.0 . 1.1; 1.2; 1.2; 1.3; 1.4; 1.5; 1.6; 1.7; 1.9; 2.0; 2.3; 2.5; 2.9; 3.4; 4.0; 5.0; 6.7; 10.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 . 1.2: 1.2: 1.3: 1.4: 1.5: 1.6: 1.7: 1.8: 2.0: 2.2: 2.4: 2.7: 3.1: 3.6: 4.3: 5.3: 7.1: 10.6 . . . . . . . . . . . . . . . . . 1.2 . 1.2: 1.3: 1.4: 1.4: 1.5: 1.6: 1.8: 1.9: 2.1: 2.3: 2.5: 2.8: 3.2: 3.8: 4.5: 5.6: 7.5: 11.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 . 2 . 1 . 3 : 1 . 4 : 1 . 4 : 1 . 5 : 1 . 6 : 1 . 7 : 1 . 9 : 2 . 0 : 2 . 2 : 2 . 4 : 2 . 7 : 3 . 0 : 3 . 4 : 4 . ·0 : 4 . 8 : 5 . 9 : 7 . 9 : 11 . 8 . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 . 1.4: 1.4: 1.5: 1.6: 1.7: 1.8: 2.0: 2.1: 2.3: 2.5: 2.8: 3.2: 3.6: 4.2: 5.0: 6.3: 8.4: 12.5 . . . . . . . . . . . . . . . . . 1.4. 1.5:1.5:1.6:1.7:1.8:2.0:2.1:2.3:2.5:2.7:3.0:3.4:3.9:4.5:5.4:6.7:8.9:13.4 I e I e • e e e • I ' t e e e e . . . . . . . . . . . . . . . . . 1.5. 1.6:1.6:1.7:1.8:2.0:2.1:2.2:2.4:2.6:2.9:3.2:3.6:4.1:4.8:5.8:7.2:9.6:14.3 . . 1.6. 1.1; 1.8; 1.9; 2.o; 2.1; 2.2; 2.4; 2.6; 2.8; 3.1; 3.5; 3.9 .; 4.4; 5.2; 6.2; 7.7;10.3; 15.4 . . . . . . . . . . . . . . . . . . . . 1.7. 1.8:1.9:2.0:2.1:2.2:2.4:2.6:2.8:3.1:3.4:3.8:4.2:4.8:5.6:6.7:8.4:11.2:16.7 1.9 . 2.0 ~ 2.1 ~ 2.2 ~ 2.3 ~ 2.5 ~ 2.6 ~ 2.8 ~ 3.1 ~ 3.4 ~ 3.7 ~ 4.1 ~ 4.6 ~ 5.2 ~ 6.1 ~ 7.3 ~ 9.1 ~12.2 ~ 18.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 . 2.0 . 2.2. 2.3. 2.4. 2.5. 2.7. 2.9. 3.1. 3.4. 3.7. 4.0: 4.5: 5.0: 5.8: 6.7: 8.0:10.0:13.4: 20.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 : 2 . 3 : 2 . 4 : 2 . 5 : 2 . 7 : 2 . 8 : 3 . 0 . 3 . 2 . 3. 5 . 3. 8 . 4. 1 . 4. 5 : 5 . 0 : 5 . 6 : 6. 4 : 7. 5 : 8. 9 : 11.2 : 14. 9 : 2 2 . 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 : 2 . 5 : 2 . 7 : 2 . 8 : 3. 0 : 3. 2 : 3. 4 . 3. 6 . 3 . 9 : 4. 2 : 4. 6 . 5 . 0 : 5 . 6 : 6. 3 : 7. 2 : 8. 4 : 10 . 0 : 12 . 5 : 16. 7 : 2 5 . 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 : 2 . 9 : 3. 1 : 3. 2 : 3. 4 : 3. 6 : 3. 9 : 4. 1 : 4. 4 : 4. 8 : 5. 7 : 5 . 8 : 6. 4 : 7. 2 : 8. 2 : 9. 6 :11 . 5 :14. 3 :19. 1 : 2 8. 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 : 3.4 : 3.6: 3.8: 4.0: 4.2: 4.5: 4 ,8: 5.2: 5.6: 6.1: 6.7: 7.5: 8.4: 9.6:11.2 :13.4:16.7:22.3: 33.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 : 4.0 : 4.3: 4.5: 4.8: 5.0: 5.4: 5.8: 6.2: 6.7: 7.3: 8.0: 8.9:10.0:11.5 :13.4:16.0:20.0:26.7: 40.0 . . . . . . . . . . . . . . . . . . 20 : 5.0 : 5.3: 5.6: 5.9: 6.3: 6.7: 7.2: 7 . 7: 8.4: 9.1:10.0:11.2:12.5:14.3:16.7:20.0:25.0:33.4: 50.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 : 6.7 : 7.1: 7.5: 7.9: 8.4: 8.9: 9.6:10.3:11.2:12.2:13.4:14.9:16.7:19.1 :22.3:26.7:33.4:44.5: 66.7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 : 10.0 :10.6:11.2:11.8:12.5:13.4:14.3:15.4:16.7:18.2:20.0:22.3:25.0:28.6:33.4:40.0:50.0:66.7:100.0 The information in Table 3 is in 5% gradations. Seed analyses seldom come out as a whole number ending in "0" or 11 5 11 • It is sufficiently accurate to use the nearest whole number. For example: 37.50% to 42.49% would be considered as 40%. 42.50% to 47.49% would be considered as 45%. 

EC61-135  Pure Live Seed Method for Determining Requirements for Grass Seedings...

UNL | Libraries

University of Nebraska - Lincoln
DigitalCommons@University of Nebraska - Lincoln
Historical Materials from University of Nebraska-
Lincoln Extension Extension
1961
EC61-135 Pure Live Seed Method for
Determining Requirements for Grass Seedings...
D. F. Burzlaff
J. C. Swinbank
Follow this and additional works at: http://digitalcommons.unl.edu/extensionhist
This Article is brought to you for free and open access by the Extension at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for
inclusion in Historical Materials from University of Nebraska-Lincoln Extension by an authorized administrator of DigitalCommons@University of
Nebraska - Lincoln.
Burzlaff, D. F. and Swinbank, J. C., "EC61-135 Pure Live Seed Method for Determining Requirements for Grass Seedings..." (1961).
Historical Materials from University of Nebraska-Lincoln Extension. 3515.
http://digitalcommons.unl.edu/extensionhist/3515
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EED METHOD FOR 
DETERMINING REQUIREMENTS 
FOR GRASS SEEDINGS ....... . 
EXTENSION SERVICE 
UNIVERSITY OF NEBRASKA COLLEGE OF AGRICULTURE 
AND U . S . DEPARTMENT OF AGRICULTURE 
COOPERATING 
E . F. FROLIK. DEAN E . W . JANIKE, DIRECTOR 
PURE LIVE SEED CPLS) METHOD 
FOR DETERMINING REQIREMENTS FOR GRASS SEEDINGS 
D. F. Burzlaff and J. C . SwinbankJ/ 
The "Pure Live Seed" Method 
Grass seed lots may vary widely in quality and price. Some lots of seed--
especially native grasses--contain inert material, undesirable mixtures, weed seeds, 
and grass seeds that will not grow. Since only live seeds of the desired crop are of 
value, the pure live seed way is the business-like way to buy, plant and sell grass 
seed. It assures farmers and ranchers of full value for their seed dollar and protects 
producers and handlers of high quality seed against price penalties experienced in 
competition with low quality seed priced without regard to purity and germination. 
Pure live seed planting rates supply the desired number of live seeds per acre and better 
stands can be expected. 
The term "pure live seed" (PLS) refers to the amount of live seed of the desired crop 
which is present in any lot of seed material. The percentage of pure live seed present 
is determined by multiplying the purity times the germination. Seed, if properly labeled, 
will have information attached to show the purity, germination, weed seeds, hard seeds, 
other crop seed, and inert matter. Thus, the seed tag supplies the information needed 
to plan seeding mixtures on a pure live seed basis. 
Calculating Mixtures on a PLS Basis 
Calculating mixtures for grass seedings need not be difficult or confusing. Actu-
ally, this is not different from determining the amount of crude protein in a 100-pound 
bag of 40% protein supplement. Similar calculations are performed each time you decide 
how many pounds of a 45% fertilizer are needed to apply 100 pounds of the needed ele-
ment. This circular has been prepared to acquaint you with the procedure for making 
grass-seeding calculations on the basis of pure live seed content. 
Each County Extension Office, in cooperation with the Soil Conservation Service 
and the County ASC Committee, should develop basic mixtures of desirable grasses for 
each site in the county. An example of a set of mixtures and rates of seeding is pre-
sented in Table 1. These seeding rates are determined on the basis of approximately 
20 live seeds per square foot. 
Any grass included in a mixture should be adapted to the soils and climate of the 
area. Table 2 shows many of the grasses recommended for seeding in Nebraska. The 
areas of the state in which each grass is adapted for production are indicated. 
Table 2 shows the approximate number of pounds of PLS of each grass that must be 
seeded to assure at least 20 live seeds per square foot. This information is used in 
determining the amount of each species to be included in the mixture. 
J/ Specialists in Range Management and Agronomy respectively, University of Nebraska 
Agricultural Extension Service. 
3 
• 
To see hOW' mixtures are formulated refer to Table 1. Here is an example from Table 1 
of the first choice mixture for hardland sites in Sherman County: 
Species 
Little bluestem 
Side-oats grama 
Western wheatgrass 
Switchgrass 
% ofMixture 
30 
20 
20 
30 
Lbs . PLS Per Acre 
1.1 
1.0 
1.6 
1.0 
4.7 
The percentage figures represent the amount of each grass in the mixture. The 
amount of each species included depends upon what composition is desired in the forage 
to be produced. If legumes are included I they usually do not represent more than 20 
percent of a forage mixture. 
The pounds of PLS per acre are determined by multiplying the percentage figure for 
each species by the number of pounds of PLS required to make a full seeding (Table 2) . 
In the above example: 
Little bluestem 
Side-oats grama 
Western wheatgrass 
Switchgrass 
30% 
20% 
20% 
30% 
Planning Seedings on a PLS Basis 
X 
X 
X 
X 
3.5 = 
4.5 = 
8.0 . = 
3.0 = 
1 . 0 5 or 1 . 1 * lbs . PLS per acre 
. 90 lb. or 1 . 0 * lb. PLS per acre 
1 . 6 lbs . PLS per acre 
.90 lb. or 1.0* lb. PLS per acre 
When planning a grass seeding 1 first consider the purpose of the seeding and the 
site on which it is to be made. Then select the proper mixture from the list of grass 
seeding mixtures developed for your county. 
Let us assume 1 for example I that you desire to make a seeding on 40 acres of land. 
After some consideration you select the follOW'ing basic mixture: 
Species 
Little bluestem 
Side-oats grama 
Blue grama 
Western wheatgrass 
Percent of Each Species 
In Mixture 
SO% 
25% 
15% 
10% 
Pounds 
PLS Per Acre 
1.8 
1.2 
. 3 
.8 
*When computing seeding rates, always remember to increase any fractional value 
to the next highest tenth of a pound. 
4 
To determine the amount of PLS required for the seeding 1 multiply the number of 
acres to be seeded times the pounds of PLS required per acre for each species. This 
would give you the following information: 
Lbs. Acres Pounds PLS 
Grass Mixture PLS/Acre to be seeded to be purchased 
Little bluestem 50% 1.8 40 72 
Side-oats grama 25% 1.2 40 48 
Blue grama 15% . 3 40 12 
Western wheatgrass 10% .8 40 32 
Take this information to the seed dealer to determine the amount of bulk seed you 
. need to get the required amount of pure live seed. The amount is determined by applying 
the information on the seed tag to the information in Table 3 . 
For the example above assume the follow-ing seed quality: 
Species 
Little bluestem 
Side-oats grama 
Blue grama 
Western wheatgrass 
Purity 
50% 
40% 
55% 
80% 
Germination 
60% 
50% 
60% 
80% 
To determine the amount of little bluestem to purchase from seed of the above quality 1 
find 11 5 0 11 in the column headed "purity. 11 Follow horizontally along this line to the 
column for the germination percentage of 60. At this point of intersection is found the 
number 3. 4. This means for every pound of PLS desired 1 3 . 4 pounds of rna terial must 
be purchased. For this seeding it would require 3. 4 x 72 I or approximately 2 45 pounds 
of little blue stem. 
This procedure is repeated for each species in the mixture 1 using their respective 
purity and germination values. The seed requirements for making your grass seeding 
would be: 
Little bluestem 
Side-oats grama 
Blue grama 
Western wheatgrass 
PLS and Native Harvested Mixtures of Grasses 
245 pounds 
240 pounds 
37 pounds 
52 pounds 
574 pounds total 
What procedure must be follovved when a seeding is planned that consists of a native 
grass mixture? This mixture may be harvested mixture or a mixture made by the seed 
dealer. 
The components of the mixture with the purity and germination values for each must 
be known at the time the seeding is planned. This means there must be a seed analysis 
available on all locally harvested seed. 
5 
Assume in the above situation that little bluestem seed is not available except in a 
native harvested mixture. This mixture could be of the following analysis: 
Purity Germination PLS 
Little bluestem 35.6% 52% 18.5% 
Big bluestem 5.2% 51% 2.5% 
Side-oats grama 5.1% 60% 3.1% 
Inert and foreign rna tter 54.1% 
This analysis tells us that in each 100 pound bag of this mixture there are 18.5 
pounds of little blue stem (PLS) I 2. 5 pounds of big bluestem (PLS) 1 and 3.1 pounds 
of s_ide-oats grama (PLS). 
Since big blues tern is adapted to this site I it may be substituted for some of the 
little blue stem in the mixture. In this case 21 pounds of big bluestem and little blue-
stem (PLS) would be available in each 100 pounds of bulk material. The seeding called 
for 68 pounds PLS of little bluestem. Using the above mixture it would require 325 pounds 
of bulk material to provide this amount of pure live seed. In addition this 325 pounds 
would furnish 10 of the necessary 48 pounds PLS of side-oats grama. 
Determining the Cost of Pure Live Seed 
Traditionally I grass seed prices have been quoted on the bulk seed basis. However, 
because of widespread interest in the pure-live seed method many dealers are now quot-
ing on a PLS basis. 
The cost of the pure live seed in any bulk seed lot can be determined by multiplying 
the purity times the germination and dividing the result into the bulk seed price. Here 
is the formula: 
Bulk Seed Price 
= Cost of Pure Live Seed Purity x Germination 
Example: 
Step l -- Substitute appropriate figures in the formula: 
Bulk Seed Price 75¢/lb. 
= Cost of PLS 50% (Purity) x 60% (Germination) 
Step 2 -- Determine the cost of PLS: 
$0.75 
= 
.50 X .60 
$0.75 
.3000 = $2.50 for each pound of Pure Live Seed 
This formula provides a means of comparing the "actual" or "real" value of different 
lots of seed. The price per pound of pure live seed and not the bulk seed price deter-
mines which seed lot is the better buy. 
6 
Farmers who buy grass seed on a pure live seed basis for the first time may be 
concerned because the price per pound of pure live seed is greater than .that of bulk 
seed. As the formula shows, the cost of the seed that will grow is no greater and in 
many cases may be less than that offered at a low bulk seed price. It should also be 
borne in mind that pure live seed planting rates are based on the amount of live seed 
needed to give the desired stand. 
Acknowledgment 
The authors express appreciation toE. C. Conard, Associate Professor of Agronomy, 
University of Nebraska, for helpful suggestions and other assistance in the preparation 
of this publication. 
7 
co 
1st CHOICE 
Percent 
of PLS 
Table 1. (Example) Suggested Seeding Mixtures 
For 
Sherman County 
2nd CHOICE 
Percent 
of PLS 
3rd CHOICE 
Percent 
of 
SQecies Mixture Lbs/Acre Species Mixture Lbs/Acre Species Mixture 
Hardland Hard land Hard land 
Little bluestem 30 l.l Switchgrass 25 .8 Western 
Side-oats grama 20 l.O Big bluestem 25 1.5 wheatgrass 20 
Western Indian grass 25 1.3 Intermediate 
wheatgrass 20 1.6 Side-oats grama 25 1.2 wheatgrass 
Switchgrass 30 l..:.Q 4.8 or 60 
4.7 Bromegrass 
Alfalfa 20 
Sandy land Sandy land Sandy land 
Sand bluestem 30 2.4 Switchgrass 50 1.5 Sand lovegrass 40 
Switchgrass 30 l.O Sand lovegra s s 50 .5 I1;1termediate 
Prairie sandreed 20 . 7 2 .0 wheatgrass 40 
Sand lovegrass 20 .2 Alfalfa 20 
4.3 
Wetland Wetland Wetland 
Big bluestem 25 1.5 Reed Tall wheatgrass 50 
Indian grass 25 1.3 canarygrass 40 .8 Switchgrass 50 
Switchgrass 30 l.O Bromegrass 40 2. 6 . 
Red clover 20 _J_ Redtop 20 _J_ 
4.5 3.5 
- --- --- - -
PLS 
Lbs/Acre 
1.6 
6.0 
3.9 
. 8 
6. 3 or 8. 4 
. 6 
4.0 
. 8 
5.4 
5 .5 
1.5 
7.0 
Table 2. Grasses commonly seeded for the establishment of permanent cover in Nebraska 
and recommended planting rates in terms of pure-live-seed. 
(Select a grass mixture which will result in about 20 live seeds per square foot--select 
column applicable to area of the state and the site condition.) 
Eastern 
.1/Required Pounds 
Central Western Pure-Live-Seed Per 
Eligible Acre (to plant ap-
Grasses Hard- Sandy Wet Hard- Sandy Wet Hard-! Sandy Wet proximately 2 0 live 
and Legumes land land land seeds per sq. ft.) 
Bromegrass - - - - - - - 6.5 
Tall fescue - - - - 4.0 
Orchardgrass - - - - - 2.0 
Intermediate 
wheatgrass - - - - - - 10.0 
TaU wheatgrass - - - - - 11.0 
Crested 
wheatgrass - - - - 5 .0 
Russian wildrye - - 5 .0 
Redtop - - - .4** 
Blue grarna - - - - - - 1.5 
Side-oats grama - - - - - - 4.5 
Buffalo grass - - 4.0* 
Sand bluestem - - - 8.0 
Big bluestem - - - - - - - - 6.0 
Little bluestem - - - - - - 3.5 
Indian grass - - - - - - - - 5.0 
Switchgrass - - - - - - - - 3.0 
Sand lovegrass - - - - - 1.0 
Prairie sandreed - - - 3.5 
Green needlegrass - - - - 5.0 
Slender 
wheatgrass - - 5 .5 
Western 
wheatgrass - - - - - - - - 8.0 
Canada wildrye - - - - - 7.5 
Reed canarygra s s - - - - 2.0 
Alfalfa - - - - - - - - 4.0 
Sweet clover - - - - - - - - - 3.5 
Red clover - - - - - 3.5 
Alsike clover - - - 1.5 
Birdsfoot 
trefoil - - - - - 2.5 
Hairy vetch - - - - - 24.0*** 
Lespedeza - - 4.0 
* Based on treated seed at the rate of approximately 4 pure live burs per square foot. 
** Provides for approximately 40 pure live seeds per square foot. 
*** Provides for approximately 10 pure live seeds per square foot. 
.1/ A planting rate of 20 pure live seeds per square foot is considered adequate under good 
conditions of seedbed preparation and weather. Somewhat higher rates are suggested 
where obtaining a full, usable stand in a minimum time justifies the added cost. 
9 
Table 3. Pounds of Grass Seed Material Required to Yield One Pound of Pure Live Seed 
% : Percent Germination 
Purity : 100 : 95 : 90 : 85 : 80 : 75 : 70 : 65 : 60 : 55 : 50 : 45 : 40 : 35 : 30 : 25 : 20 15 : 10 
100 
95 
90 
85 
80 
75 
70 
65 
...... 60 
o-
55 
. . 
1.0 . 1.1; 1.2; 1.2; 1.3; 1.4; 1.5; 1.6; 1.7; 1.9; 2.0; 2.3; 2.5; 2.9; 3.4; 4.0; 5.0; 6.7; 10.0 
. . . . . . . . . . . . . . . . 
. . . . . . . . . . . . . . . . 
1.1 . 1.2: 1.2: 1.3: 1.4: 1.5: 1.6: 1.7: 1.8: 2.0: 2.2: 2.4: 2.7: 3.1: 3.6: 4.3: 5.3: 7.1: 10.6 
. . . . . . . . . . . . . . . . . 
1.2 . 1.2: 1.3: 1.4: 1.4: 1.5: 1.6: 1.8: 1.9: 2.1: 2.3: 2.5: 2.8: 3.2: 3.8: 4.5: 5.6: 7.5: 11.2 
. . . . . . . . . . . 
. . . . . . . . . . . . . . . . . 
1 . 2 . 1 . 3 : 1 . 4 : 1 . 4 : 1 . 5 : 1 . 6 : 1 . 7 : 1 . 9 : 2 . 0 : 2 . 2 : 2 . 4 : 2 . 7 : 3 . 0 : 3 . 4 : 4 . ·0 : 4 . 8 : 5 . 9 : 7 . 9 : 11 . 8 
. . . . . . . . . . . 
. . . . . . . . . . . . . . . 
1.3 . 1.4: 1.4: 1.5: 1.6: 1.7: 1.8: 2.0: 2.1: 2.3: 2.5: 2.8: 3.2: 3.6: 4.2: 5.0: 6.3: 8.4: 12.5 
. . . . . . . . . . . . . . . . . 
1.4. 1.5:1.5:1.6:1.7:1.8:2.0:2.1:2.3:2.5:2.7:3.0:3.4:3.9:4.5:5.4:6.7:8.9:13.4 
I e I e • e e e • I ' t e e e e 
. . . . . . . . . . . . . . . . . 
1.5. 1.6:1.6:1.7:1.8:2.0:2.1:2.2:2.4:2.6:2.9:3.2:3.6:4.1:4.8:5.8:7.2:9.6:14.3 
. . 
1.6. 1.1; 1.8; 1.9; 2.o; 2.1; 2.2; 2.4; 2.6; 2.8; 3.1; 3.5; 3.9 .; 4.4; 5.2; 6.2; 7.7;10.3; 15.4 
. . . . . . . . . . 
. . . . . . . . . . 
1.7. 1.8:1.9:2.0:2.1:2.2:2.4:2.6:2.8:3.1:3.4:3.8:4.2:4.8:5.6:6.7:8.4:11.2:16.7 
1.9 . 2.0 ~ 2.1 ~ 2.2 ~ 2.3 ~ 2.5 ~ 2.6 ~ 2.8 ~ 3.1 ~ 3.4 ~ 3.7 ~ 4.1 ~ 4.6 ~ 5.2 ~ 6.1 ~ 7.3 ~ 9.1 ~12.2 ~ 18.2 
. . . . . . . . . . . . . . . . . . . 
. . . . . . . . . . . . . . . . . . . 
50 . 2.0 . 2.2. 2.3. 2.4. 2.5. 2.7. 2.9. 3.1. 3.4. 3.7. 4.0: 4.5: 5.0: 5.8: 6.7: 8.0:10.0:13.4: 20.0 
. . . . . . . . . . . . . . . . . 
. . . . . . . . . . . . . . . . . 
45 : 2 . 3 : 2 . 4 : 2 . 5 : 2 . 7 : 2 . 8 : 3 . 0 . 3 . 2 . 3. 5 . 3. 8 . 4. 1 . 4. 5 : 5 . 0 : 5 . 6 : 6. 4 : 7. 5 : 8. 9 : 11.2 : 14. 9 : 2 2 . 3 
. . . . . . . . . . . . . . . . . 
. . . . . . . . . . . . . . . . . 
40 : 2 . 5 : 2 . 7 : 2 . 8 : 3. 0 : 3. 2 : 3. 4 . 3. 6 . 3 . 9 : 4. 2 : 4. 6 . 5 . 0 : 5 . 6 : 6. 3 : 7. 2 : 8. 4 : 10 . 0 : 12 . 5 : 16. 7 : 2 5 . 0 
. . . . . . . . . . . . . . . . 
. . . . . . . . . . . . . . . . . 
35 : 2 . 9 : 3. 1 : 3. 2 : 3. 4 : 3. 6 : 3. 9 : 4. 1 : 4. 4 : 4. 8 : 5. 7 : 5 . 8 : 6. 4 : 7. 2 : 8. 2 : 9. 6 :11 . 5 :14. 3 :19. 1 : 2 8. 6 
. . . . . . . . . . . . . . . . . 
. . . . . . . . . . . . . . . . . 
30 : 3.4 : 3.6: 3.8: 4.0: 4.2: 4.5: 4 ,8: 5.2: 5.6: 6.1: 6.7: 7.5: 8.4: 9.6:11.2 :13.4:16.7:22.3: 33.4 
. . . . . . . . . . . . . . . . . . . 
. . . . . . . . . . . . . . . . . . . 
25 : 4.0 : 4.3: 4.5: 4.8: 5.0: 5.4: 5.8: 6.2: 6.7: 7.3: 8.0: 8.9:10.0:11.5 :13.4:16.0:20.0:26.7: 40.0 
. . . . . . . . . 
. . . . . . . . . 
20 : 5.0 : 5.3: 5.6: 5.9: 6.3: 6.7: 7.2: 7 . 7: 8.4: 9.1:10.0:11.2:12.5:14.3:16.7:20.0:25.0:33.4: 50.0 
. . . . . . . . . . . . . . . . . . . 
. . . . . . . . . . . . . . . . . . . 
15 : 6.7 : 7.1: 7.5: 7.9: 8.4: 8.9: 9.6:10.3:11.2:12.2:13.4:14.9:16.7:19.1 :22.3:26.7:33.4:44.5: 66.7 
. . . . . . . . . . . . . . . . . . . 
. . . . . . . . . . . . . . . . . . . 
10 : 10.0 :10.6:11.2:11.8:12.5:13.4:14.3:15.4:16.7:18.2:20.0:22.3:25.0:28.6:33.4:40.0:50.0:66.7:100.0 
The information in Table 3 is in 5% gradations. Seed analyses seldom come out as a whole number ending in "0" or 11 5 11 • It 
is sufficiently accurate to use the nearest whole number. For example: 37.50% to 42.49% would be considered as 40%. 
42.50% to 47.49% would be considered as 45%. 


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EC61-135 Pure Live Seed Method for Determining Requirements for Grass Seedings...

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