STUDIES OF MACHINES FOR INCORPORATION OFPRE-EMERGENT HERBICIDES

R. Lai and W.B. Reed

Agricultural Engineering Department, University of Saskatchewan, Saskatoon, Sask. S7N 0 WO

Received 2 November 1976

Lai, R. and W.B. Reed 1977. Studies of machines for incorporation of pre-emergent herbicides. Can. Agric. Eng. 19: 6-11.

The depth and uniformity of herbicide incorporation using both granular and liquid forms by several implements is reported.The results indicated substantial differences in the incorporation capabilities of these implements. The disc-type implementsprovided deeper incorporation because of soil inversion by the discs. The tine-type implements which stirred the soil did notprovide deep incorporation. The discer equipped with the Normand spray boom attachment provided a shallow or deepincorporation depending upon the position of the spray boom. The differences in incorporation capabilities of variousimplements will require proper selection of implement depending on the herbicide and the crop to be treated.

INTRODUCTION

Although not many of the herbicides inuse today are pre-emergent, the ones in useare of great significance, particularly for thecontrol of wild oats. The successful use of

these herbicides depends on correct application and incorporation. Wasted chemical,damage to crops and poor weed control canresult from incorrect application and incorporation procedures.

Pre-emergent herbicides are available ineither liquid or granular form; the mostcommon of these is triallate used for wild

oats control. The pre-emergent herbicidesrequire incorporation into the soil just afterapplication. The depth of incorporationmay vary depending on the kind of weed tobe controlled and the crop that is to begrown. For example, trifluralin should bemixed relatively deeply for control of wildoats whereas a shallow incorporation ismore satisfactory for control of greenfoxtail.

According to Ashford (1975), a triallategranule has to be within half a centimeter ofa growing wild oat to have any effect. Thisshows the importance of a uniform application and thorough incorporation of theherbicide. Moreover, a normal applicationrate of 14 kg/ha of triallate granules whenincorporated to a depth of 5 cm means thatone part of the herbicide has to be mixedwith nearly 26,000 parts of the soil.

Various implements are used to incorporate herbicides. The common ones arediscer (common name for one-way discharrow), tandem disc harrow, drag harrow,and cultivator.

Bode et el. (1969) studied the incorporation of trifluralin with various implementsand reported that deeper incorporation wasobtained with a tandem disc harrow, while ashallow incorporation resulted from a power rotary cultivator. Hulbert and Menzel(1953) used radioactive tracers and granulesto study the soil mixing characteristics ofvarious tillage implements and reported thatdisc harrowing followed by spring toothharrows resulted in fairly uniform distribution of granules. Holroyd (1964) studied the

incorporation of fluorescent dye with aspring tine harrow, a rotary cultivator and achain harrow and reported that increasingthe depth and frequency of operation increased the depth of incorporation. Matthews (1970) used chloride analysis forincorporation studies and reported thatuniform incorporation in both horizontaland vertical directions was obtained with

single discing, double discing and cross-discing operations. The cross-discing operation did not seem to improve the distribution over the double disc operation. Butlerand Siemens (1972) reported incorporationof pesticides with a tandem disc harrow anda cultivator and observed that incorporationwith the tandem disc improved with fasterspeeds and larger gang angles and a secondoperation resulted in deeper and moreuniform incorporation. Incorporation withthe field cultivator was not as good as withthe tandem disc harrow and concentration

of granules appeared in rows.There appears to be a considerable

difference among various incorporating im-pements with regard to their ability toincorporate both granular and liquid herbicides to a desired uniformity and depth.Therefore the project was undertaken toevaluate the following:1. The incorporation capabilities of com

mon farm implements.2. The effects of speed, mode of incorpor

ation and disc angle on the verticaldistribution of granules when incorporated with a tandem disc harrow.

3. The effects of boom position, speed anddepth of tillage on the vertical distribution of the liquid when using the Normand attachment on a discer.

4. The effects of the spout position of theGandy applicator on the vertical distribution of granules when mounted behind adiscer.

EQUIPMENT AND PROCEDURES

Description of Incorporating Implements

Common farm implements used fortillage operations were selected for incor

CANADIAN AGRICULTURAL ENGINEERING. VOL. 19 NO. 1, JUNE 1977

poration of granules and liquid spray. Theseare listed below:

Discer — A 2.75-m Massey Ferguson discerwith the disc size of 0.5 m spaced 0.18 mapart. The Normand spray attachment andthe Gandy applicator were also attachedbehind the discer.

Tandem disc harrow — A 6.1-m Inter

national Harvestor tandem disc harrow with

the disc size of0.5 m spaced 0.19 m apart andthe disc gangs at an angle of 15°.Field cultivator — A 6.1-m International

Harvestor "vibra shank" cultivator, sweepsize 0.23 m spaced 0.2 m apart and followedby drag diamond harrows.Deep tillage cultivator — A 3.05-m MasseyFerguson cultivator, sweep size 0.4 m spaced0.3 apart and followed by drag diamondharrows.

Spike tooth harrows — Three sections of0.9-m-wide spike tooth diamond harrows.Rod weeder — A 3.05-m Morris rod weeder.

Tracer Technique

Various tracer techniques have been usedto study the incorporation capabilities oftillage implements. The technique used inthis study has been described by Lai andReed (in prep.).

Attaclay granules dyed with 0.2% ura-nine dye (sodium fluorescein) were appliedwith a Gandy applicator at a rate of 34kg/ha, about twice the normal applicationrate of triallate granules. For liquid application, 0.2% solution of uranine dye in distilledwater was sprayed with different nozzles at arate of 112 liters/ha.

Granule and Liquid Application

A 3.05-m-wide Gandy applicator wasused for spreading granules on the soilsurface at a rate of 34 kg/ha. The lateraldistribution of granules from the Gandyapplicator was determined in both the laband the field. The distribution in the lab was

obtained from the calibration of the applicator, while the field distribution was obtainedby taking soil samples after applying thegranules but before incorporation. Thedepth of sampling was very shallow for thesesamples.

TABLE I EXPERIMENTAL PLAN FOR

THE TANDEM DISC HARROW

STUDY

Test Speed Disc angle Mode of

number (km/h) (degrees) incorporation!

1 5 16 Single2 8 16 Cross

3 8 16 Single4 8 20 Single5 8 20 Cross

6 5 20 Cross

tSingle, single pass with harrow in the direction ofgranules application.Cross, cross-harrowing, i.e., second pass at rightangles to the single pass.

TABLE II EXPERIMENTAL PLAN FOR

THE NORMAND AND THE

GANDY ATTACHMENT WITH

THE DISCER

Test Depthnumber (cm)

Speed(km/h)

Nozzle

locationtor spout

Hor. Vert, a

Normand attachment

1 7.5

2 7.5

3 10.0

4 10.0

5 7.5

6 7.5

8

5

8

5

8

5

50

50

50

50

31.5

12.5

50 36°

50 36°

50 36°

50 36°

40 55°

50 65°

Gandy attachment

7 7.5

8 7.5

8

8

2.5

15.0

63.5 90°

63.5 90°

t Hor. = Horizontal position of nozzle tip or spoutopening from the discs in cm.Vert. - Vertical position of nozzle tip or spoutopening from the lowest part of the disc in cm.a - spray angle or spout angle in degrees.

Floodjet TK 2.5 and Teejet 6502 nozzleswere used for spraying liquid for determining their uniformity of distributionpatterns in the lab and on the soil surface.However, Teejet 65015 nozzles were used forthe Normand spray attachment and Flood-jet TK 2.5 nozzles were used for the liquidincorporation study. The nozzles were operated to deliver 112 liters/ha.

The tracer granules and the liquid wereapplied in front of the tractor. However,with the Normand spray attachment andwith the Gandy attachment behind thediscer, the spray or granules were directedon to the turning soil. For both granular andliquid applications, a strip of land equal tothe width of the applicator (3.05 m) wasused. The effective length of the experimental strip was 32 m.

Experimental Procedure

Incorporation of granules and liquid wascarried out just after the application or

simultaneously with the application, depending upon the kind of experiment. Thedepth of tillage was maintained close to 7.5cm for all the implements. However, thepenetration of rod weeder and spike toothharrows was shallower. Where necessary thetillage was also carried out to the 10-cmdepth. The speed of operation was maintained at 8 km/h. In each case, a singleoperation was carried out for incorporationexcept in the case of spike tooth harrowswhere incorporation was carried out bycross-harrowing.

Experiments were also conducted todetermine the effects of preincorporationtillage depth on the depth of incorporation.The depths of tillage considered were 5 cmand 10 cm.

Tandem disc harrow

The effects of disc angle, single vs. adouble-cross operation, and travel speed onincorporation depth were measured. Thedetails are given in Table I.

Discer with Normand and Gandy attachment

The effects of the spray nozzle positionwith the Normand attachment and the spoutposition of the Gandy applicator on thedepth of incorporation were determined. Inaddition, the effects of travel speed andtillage depth were included in the study.Table 2 lists specific details.

Soil Sampling and Dye Extraction

Vertical distribution

Soil samples were taken immediatelyafter incorporation. The strip of incorporated land was divided into four sections,each section thus representing one replicate.Three sample locations across the width ofincorporation and three along the line oftravel were chosen in each section. Positions

of wheel tracks were avoided in takingsamples. Soil samples were taken at intervalsof 3.05 m along the line of travel.

At each sample location, three sampleswere taken adjacent to each other down tothe depth of incorporation. Each of thesesamples was divided into three parts fordepths of 0—2.5 cm, 2.5—5.0 cm, and 5.0—7.5 cm. Thus, at each location, nine samplesof approximately 16.4 cm3 of soil werecollected. A total of 81 samples were takenfor each replicate for 7.5-cm depth ofincorporation.

Lateral distribution

Soil samples for lateral distribution weretaken at three random locations along theline of travel. For the granular experiment, atotal of 54 samples were taken at eachlocation along the middle for a width of 1.6m between the tractor wheels. The width of

1.3 m between the front wheels of the MF

1150 tractor was a limiting factor.For the lateral distribution of liquid with

Teejet 6502 and Floodjet TK 2.5 nozzles, soilsamples were taken after spraying the liquidon the soil surface and after incorporation

by two passes perpendicular to each otherwith a spike tooth harrow. A total of 39samples were taken along the middle of 1.16-m width in order to avoid wheel tracks.

The procedure for extracting dye anddetermining the fluorescence level for eachsample has been described by Lai and Reed(in prep.).

Data Analysis

For a vertical distribution of the granulesand the liquid, a total of 27 fluorescencereadings obtained in a replicate were averaged for each soil layer. Each of these valueswas transformed to the percentage of thesum of the fluorescence values of the

replicate. These percent values representedthe quantity of the granules or the liquidincorporated at various depth levels. Afurther average of these percentages of fourreplicates represented the quantity of thegranules or the liquid for each soil layerwhich was incorporated in that layer for atest trial. Thus, a total of 108 fluorescencereadings were averaged for each depth levelfor every test. The uniformity of incorporation at different depths was estimatedfrom the coefficients of variation which were

calculated with 108 values from all the

replicates at each depth level.Analysis of variance and Duncan's new

multiple range test were applied to varioustest trials at individual depth level. Similartreatments were also paired for this analysisfor determining the effect ofa single variableon incorporation.

The fluorescence readings were averagedover the three replicates for the lateraldistribution of the granules and the liquid.These average values for each sample werethen transformed to the percentage of thesum of all the values ofa test. This procedureresulted in a common mean for similar

treatments for the purpose of comparison ofdistribution pattern. The range of values wascalculated as the percentage of the meanwhich showed the minimum and the max

imum quantity of the granules or the liquidat any location in the test strip. Thecoefficients of variation were calculated as

the measure of the uniformity of incorporation.

RESULTS AND DISCUSSION

Vertical Distribution of Granules

Figure 1 shows that the best mixing ofgranules to 7.5-cm depth in the soil wasobtained with the disc-type implements.Similar results have been reported earlier(Hulbert et al. 1953; Bode et al. 1969;Matthews 1970; Butler et al. 1972). Therewas no significant difference in the distribution between the tandem disc harrow

and the discer.

Both cultivators followed by spike toothharrows appeared to be quite similar in theirability to incorporate the granules. A higher

CANADIAN AGRICULTURAL ENGINEERING, VOL. 19 NO. 1, JUNE 1977

100

40.2 41.4 60.8 57.4 92.7

DEPTH (CM)

0-2.580 -Y///A

•< 60(ro

»-zUJ

u 4041.0

2.5-5.0

20 —36.6 35.4

50

z 30

10

13.4 17.62.6

7.2 6.60.7

TANDEM DISCER FIELD DEEP ROD

DISC CULTIVATOR TILLAGE WEEDER

CULTIVATOR

Figure 1. Incorporation of granules with various implements.

80

60

3Z

cr

40

o<rUJ

°" 20

PRE-INCORPORATION DEPTH

• 5.0 CM

111 10.0 CM

lo0-2.5 2.5-5 5-7.5 7.5-10

DEPTH (CM)

Figure 2. Effect of pre-cultivation depth on granule distribution.

SPEED 8 KM/H

DISC ANGLE 16°

aSINGLE

i

CROSS

0-2.5 2.5-5 5-7.5

SPEED 8 KM/H

DISC ANGLE 20°

•SINGLE CROSS

rM

0-2.5 2.5-5 5-7.5

DEPTH (CM)

SPEED 5 KM/H

DISC ANGLE

Dl6°SINGLE

DISC ANGLE

® 20°CROSS

0-2.5 2.5-5 5-7.5

Figure 3. Granule incorporation with the tandem disc harrow.

CANADIAN AGRICULTURAL ENGINEERING, VOL. 19 NO. 1, JUNE 1977

percentage of granules was found in the top2.5-cm layer and a lower percentage in thethird 2.5-cm layer. This difference betweencultivators and disc-type implements isthought to be due to the fact that discs causesoil inversion, whereas the cultivators onlystir the soil.

Another effect of secondary distributionof granules was also observed with cultivators followed by harrows. The combinedaction of both the implements tends to placegranules in ridges and leave furrows with fewor no granules. This row effect was alsoobserved in another experiment using triallate granules on Harmon oats (Lai andReed 1976). Butler and Siemens (1972) alsoobserved a similar row effect with a field

cultivator.

The rod weeder caused little mixing and avery high percentage of granules remained inthe top layer of soil with only a tracereaching the third layer.

Effect of Pre-incorporation Tillage Depth

Figure 2 shows the percentage of granules mixed at various intervals of depth for5.0-cm and 10.0-cm depths of tillage prior tothe application of granules.

There were nearly 22% more granules inthe top 2.5-cm layer where the soil was tilled5.0 cm deep rather than 10.0 cm deep. Thisdifference reversed in both the 2.5 — 5.0-cm

layer and the 5.0 — 7.5-cm layer wherenearly 8% more granules were deposited forthe 10.0-cm deep tillage. Statistically, thedifference of 22% of the two treatments inthe top layer was significant, while at otherdepth levels, the difference in the amount ofgranules deposited was not significant.When the soil samples were taken to a depthof 10.0 cm, nearly 6% granules were found inthe 7.5 — 10.0-cm layer when the pre-incorporation tillage was 10.0 cm deep.

These results indicate that tilling of soildeeper prior to application and incorporation of granules will result in deeper incorporation of the herbicide. This is likely theresult of the deeper penetraion of the harrowteeth which leave a deeper furrow andsubsequently, the top soil falls into itcarrying the granules with it to the furrowbottom. Where the harrow penetration wasnot as deep as in the case of 5.0-cm-deeptillage, the majority of granules remainednearer the surface.

Incorporation with the Tandem DiscHarrow

Figure 3 shows the percent of granulesmixed at various depths for different treatments with the tandem disc harrow. Stat

istically, there was no significant differenceamong various incorporation techniques ofthe tandem disc harrow.

Disc angleLittle or no difference was observed in

the concentration of granules at variousdepth intervals between 16° and 20° discangles either with a single or double pass.

80

</> 60

<

o

40 -

zUlo

20 -

SPOUT LOCATION

• 2.5 CM (HOR)

E3 15.0 CM (HOR)

SPEED 8 KM/H

-2.5 2.5-5 5-

DEPTH (CM)

7.5

Figure 4. Granule distribution with the Gandyattachment behind the discer. Spoutspositioned 63.5 cm above ground level.

However, the uniformity of incorporationwas improved significantly at the larger discangles.

Speed of travelIncreasing the speed from 5 km/h to 8

km/h provided deeper incorporation ofgranules when a single pass was made.Comparisons after two passes showed nodifference in the depth of incorporation or inquantitity of granules deposited at variousdepth intervals. The uniformity of incorporation was improved at the higher speed.

Mode of incorporationThere was little or no change in the depth

of incorporation at higher speeds between asingle and a cross operation of the tandemdisc harrow. The cross operation was twopasses at right angles to each other. Thesingle pass at alower speed of 5 km/hresulted in a shallower incorporation. Thecross operation improved the uniformity ofincorporation slightly but not sufficiently tojustify the time and expense required for thesecond pass.

Thus, it is evident that the granulesdistribution in various layers of soil is notaffected by normal variations in the speed,disc angle, and the mode of incorporationwhen incorporated with a tandem discharrow. However, the uniformity of incorporation was improved with the larger discangle, higher speeds, and cross operation.This confirms the results reported by Butlerand Siemens (1972).

Distribution with the Gandy Attachmentbehind a Discer

Figure 1 shows the percentage of thegranules deposited at various depth levelsfor two positions of the Gandy applicator atthe rear of the discer. Statistically, there wasa significant difference in the quantity ofgranules deposited at various depth levels.

Deeper incorporation of granules wasobtained as the spouts were moved closer to

75.9 47.3 62.5 61.2 83.6

DEPTH (CM)

80 —0-2.5

• *.5-5.0

37.8

40 -5.0-7.5

31.9 34.5

26.115.8

5.6 4.3

TANDEM DISCER DISCER FIELD DEEP ROD

DISC (BOOM (BOOM CULTIVATOR TILLAGE WEEDER

BEHIND) IN FRONT) CULTIVATOR

Figure 5. Incorporation of liquid with various implements.

80

BOOM POSITION

(50 + 50) 36°

• 8 KM/H

~ 5 KM/H

^1

BOOM POSITION

(50 + 50) 36°

• 8 KM/H

Zft 5 KM/H

BOOM POSITION

(50 + 31.5) 55° • 8 KM/H

(50 + 12.5) 65° H 5 KM/H

60

20

0-2.5 2.5-5 5-7.5 0-2.5 2.5-5 5-7.5 7.5-10 0-2.5 2.5-5 5-7.5

DEPTH (CM1

Figure 6. Liquid incorporation with the Normand attachment on the discer.

the disc. Nearly 52% of granules weredeposited in the top 2.5-cm layer at the spoutposition of 2.5 cm away from the disc incomparison to 66% for the 15-cm position.The uniformity of incorporation was alsobetter at the closer spout position. However,there was a difference of only 7% granules inthe top 5 cm of soil between the twopositions of spout location.

The spout position change showed asimilar trend of incorporation as did theboom position change of the Normandattachment. The spout position of 15 cmfrom the discs incorporated nearly the sameamount of granules in the top 2.5-cm soil asthe boom position of 50 cm for the Normandattachment.

It was also observed that with a slightwind, granules were blown either toward thediscs or away from the discs, dependingupon the direction of wind and the direcionof operation. Wind velocities suitable forliquid spray are likely not suitable forgranules application because going with thewind will result in deeper incorporation,

while going against the wind will result innearly all the granules being deposited onthe surface.

Vertical Distribution of Liquid

Figure 5 shows the distribution of liquidspray for various implements at three depthintervals. The distribution of liquid withinthe soil was quite similar to that obtainedwith the granules. The disc-type implementsmixed to a greater depth than the cultivatorsor rod weeder.

One additional method included the use

of a Normand spray attachment for thediscer or the one-way-disc harrow mountedbehind the disc gang. This unit directs thespray into the turning or moving soil thrownup by the discs. In this case about 75% of theliquid remained in the top layer and a verysmall amount reached the third layer. Thismethod appeared to give close to the sameresults as the rod weeder, but there is oneimportant difference. This difference is thatthe top 1-inch layer of soil from the discer isquite moist, while the same layer with the

CANADIAN AGRICULTURAL ENGINEERING, VOL. 19 NO. 1, JUNE 1977

TABLE III RANGE AND COEFFICIENTS OF VARIATION IN LATERAL DISTRIBUTION

OF GRANULES WITH VARIOUS IMPLEMENTS

Treatment

Gandy - calibrationGandy - in the fieldCross-harrowing (2 passes)Tandem disc harrow (one pass)Discer

Cultivator with harrows

Range% of mean

Coefficient of

variation

(%)

59.5-165.4 25.4

65.9-151.4 17.8

67.0-189.2 19.8

61.1-154.6 20.4

55.0-175.2 27.3

55.7-207.6 35.0

TABLE IV RANGE AND COEFFICIENTS OF VARIATION IN LATERAL DISTRIBUTION

OF LIQUID WITH TEEJET 6502 AND FLOODJET TK 2.5 NOZZLES

Treatment

Teejet 6502Calibration

Before incorporationAfter incorporationby cross-harrowing

Floodjet TK 2.5Calibration

Before incorporationAfter incorporationby cross-harrowing

rod weeder is considerably drier under mostcircumstances. This difference in moisturecould have a profound effect on the activityof the actual chemical utilization.

Distribution with the Normand Attachment

on a Discer

Figure 6 shows the percentage of liquidfound at various depths for different treatments with the Normand attachment on thediscer. Statistically, a highly significantdifference was observed in the quantity ofliquid deposited at each depth interval for allthe treatments.

Boom position and spray nozzleBringing the boom closer to the discs

increased the concentration of liquid atlower depth intervals, thus increasing thedepth of incorporation. When the positionof the spray boom of the Normand attachment was changed, the spray angle was alsochanged. Three different horizontal positions of the boom in this experiment resultedin threee different angles of spray. Thepercentage of liquid incorporated at different depth intervals at these positions and theangles of spray are shown in Figure 6.

Comparing the concentration of liquid inthe top 5-cm layer, nearly 94% was incorporated at the boom position of 50 cm, 83%at 31.5 cm and 76.8% at 12.5 cm. Thetendency of the liquid distribution amongthree depth intervals was toward a greateramount of liquid at lower depths as theboom was brought closer to the discs.However, the uniformity of incorporation

Range% of mean

Coefficient of

variation

(%)

62.1-120.7 17.3

60.1-141.7 18.9

71.9-192.5 25.3

51.6-157.0 31.3

52.0-208.9 30.2

47.3-177.3 41.0

decreased successively at each boom position.

Thus, the position of the boom was veryimportant in determining the distribution ofliquid and the depth of incorporation. Forshallow incorporation it is important tomaintain the boom in the further awayposition. It is also interesting to note that theclosest position resulted in incorporationnearly equivalent to cross operation with thetandem disc harrow.

Depth of tillageIncreasing the tillage depth of 7.5 cm to

10 cm reduced the amount of liquid deposited in the upper layer. At a speed of 8 km/h,nearly 94% of the liquid was located in thetop 5 cm when tilling 7.5 cm deep comparedto 78% when tilling 10cm deep. As expected,the differences in the upper layer resulted insimilar differences at the lower levels.

At a slower travel speed of 5 km/h, thedifference was less marked with 86% of theliquid located in the top 5-cm layer whiletilling at 7.5-cm depth and 81% when tillingat 10-cm depth.

Although the depth of incorporationincreased with the depth of tillage, theuniformity of incorporation decreased andwas much less uniform with the greaterdepth of tillage.

Speed of travelLittle or no difference was observed in

the concentration of liquid at various depthintervals between 5 km/h and 8 km/h speedof travel either at 7.5-cm or 10-cm tillagedepth. However, a shallower incorporation

CANADIAN AGRICULTURAL ENGINEERING, VOL. 19 NO. 1, JUNE 1977

was noticed at higher speed, increasing theconcentration of liquid in the top 2.5-cmlayer at 7.5 cm tillage depth; but for 10-cmtillage depth, this trend was reversed at thetop 2.5-cm layer although the difference wasless marked, with nearly 78% liquid deposited in the top 5-cm layer at 8 km/ h speedand 81% at 5 km/h speed. The uniformity ofincorporation was better at higher speed.

Thus, in general, the depth of incorporation with the Normand attachment will

depend on the boom position, depth oftillage and the speed of travel. In most cases,the depth of tillage is adjusted to give properseeding depth with a discer and it is seldomthat the seeding depth is the same as thetillage depth. So when applying and incorporating triallate while seeding, precautionsmust be taken to avoid deeper incorporationof chemical in order to prevent any cropdamage.

Lateral Distribution of Granules

Table 3 shows the range of the amount ofgranules expressed as the percent of themean over the sampling width of 1.6 m,along with the coefficient of variation foreach treatment. From the comparison of thecoefficient of variation, the field distributionof the Gandy applicator was more even thanthat in the lab. This may be the result of thegranules being bounced and dispersed moreevenly when falling to the ground. The lightwind always present during the field experiments may also have helped in making thedistribution more even.

Comparing the distribution of the Gandyapplicator in the field with the distributionof the four implements, their order may bearranged according to the degree of uniformity as follows: cross-harrowing, tandemdisc harrow, discer, cultivator with harrows.

The minimum and maximum number of

granules at any location depended on theapplicator and incorporation implement. Asshown in Table 3, the range varied from 55%to 207.6% of the average value after incorporation, while the range for the applicatorwas 65.9 — 151.4 % before incorporation.

This indicated the variation in concentra

tion of granules which at the lower concentration may not be sufficient for controllingwild oats, and at higher levels may damagethe crop. The range ofconcentration nearestto that of the Gandy attachment wasobtained with the tandem disc harrow,followed by the discer, cross-harrowing andthe cultivator with harrows. Although thedistribution of granules was more even withincorporation by cross-harrowing, the rangeof granules was higher than that of thetandem disc harrow and the discer. This mayhave been caused by the concentration ofgranules in the rows.

Lateral Distribution of Liquid

The objectives behind these trials were tocompare distribution patterns of liquid atvarious stages of nozzle operation, i.e.,

10

TEEJET 6502 NOZZLE

- CALIBRATED PATTERN C.V.= I7.3

- BEFORE INCORPORATION C.V. = 18.9

- AFTER INCORPORATION C.V. = 25.3

•*f — V- MEAN

.-Ih DISTANCE BETWEEN WHEELS -

IiiiiiIiiiiiJi60 40 20 CL 20 40 60

DISTANCE FROM CENTRE (CM)

Figure 7. Lateral distribution of liquid withTeejet 6502 nozzle.

calibration, field application before incorporation and after incorporation. The similarity of patterns and degree of dispersionwere estimated from the range expressed asthe percent of mean value and coefficients ofvariation which are given in Table 4.

The range of variation of chemical in thesampling width increased after incorporation by cross-harrowing, but there is asimilarity in the distribution patterns, asshown in Figure 7 for the Teejet 6502 nozzle.The peaks seem to occur at relatively thesame positions for the calibrated pattern andthe field patterns. Stirring the top soil bycross-harrowing did not seem to eliminatethe original applied pattern. However, theuniformity decreased, as indicated by theincreased coeffcient of variation. Since the

distributions of chemical between the patterns obtained before incorporation andafter incorporation are similar, it is best toapply the chemical uniformly over the field.

CONCLUSIONS

The results from the soil incorporationstudies indicated substantial differences inthe incorporation capabilities of variousmachines as to both depth and uniformity.In terms of uniformity of incorporation, thedescending order was as follows: (1) harrows (two passes perpendicular to each

11

other) (2) rod weeder, (3) tandem discharrow, (4) one-way disc harrow or discer,(5) light duty cultivator with harrows and(6) heavy duty cultivator with harrows.

In terms of depth of incorporation thedescending order was as follows. (1) tandemdisc harrow, (2) discer, (3) light duty cultivator, (4) heavy duty cultivator, (5) harrows, and (6) rod weeder.

The disc-type implements provideddeepest incorporation because the soil wasinverted or turned over by the disc action.Tine-type implements which stirred the soildid not tend to give deep incorporation. Thewider the spacing of the tines or shanks, theless uniform will be the results. The rod

weeder apparently did little as far as incorporation was concerned, with over 80%of liquid or granules remaining in the toplayer.

The vertical distribution of granules wasinfluenced considerably by the depth of pre-incorporation tillage. Doubling the depth ofcultivation resulted in nearly 22% fewergranules in the top 2.5-cm layer.

These results indicate that if granularherbicides are incorporated with spike toothharrows, the depth of loose soil prior toincorporation influences the depth of incorporation and the distribution of granules. It is expected that the results would besimilar with the liquid form of the herbicide.

The tandem disc harrow provided thedeepest incorporation with only one passover the field. There was practically nochange in the depth of incorporation (vertical distribution) by the second pass oroperation with the tandem disc harrow, butuniformity of incorporation was improved.Speed of travel and disc angle of the tandemdisc harrow likewise had little effect on thedepth of incorporation. Increasing the speedof travel and the disc angle resulted in moreuniform incorporation. Since higher speeds,larger disc angles, and double operation alltend to pulverize the soil, serious problemswith soil erosion could develop. Too high aspeed will also cause soil ridging.

The discer equipped with the Normandspray boom attachment could be positionedto provide shallow or deeper incorporationnearly equivalent to two operations with thetandem disc harrow. The deeper incorporation was less uniform than the shallow

incorporation. The higher speed of traveltended to give shallower but more uniformincorporation. As with other implements,the depth of incorporation is controlled tosome extent by the depth of tillage; for those

herbicides requiring shallow incorporation,the depth of tillage and position of the sprayboom is important.

The discer with a rear-mounted attach

ment for granule application resulted insatisfactory incorporation provided thespouts were positioned properly or thegranules were directed correctly. The position determined the depth of incorporationif there was no wind. Moderately windyconditions could result in an erratic incor

poration, since the granules are very easilyblown about.

Uniformity of the application of liquidherbicides from spray nozzle onto the soiland granules from granule applicators isimportant. The lateral distribution patternsfrom individual nozzles and granular applicators in the laboratory were similar inshape to the patterns of the lateral distribution in the soil after incorporation byharrows. In most cases the distribution after

incorporation by harrows was less uniformthan the distribution before incorporation.

ACKNOWLEDGMENTS

The authors wish to acknowledge the assistance and financial support provided by theEngineering Research Service, Research Branch,Agriculture Canada, Ottawa, through a DREAMproject. The project reported here was a part ofthe contract for the years 1974-76, awarded by theScience Contracting Branch, Department ofSupplies and Services, Ottawa, Ontario.

ASHFORD, R. 1975. Triallate granule spacingeffect on oat. Weed Sci. 23: 470-472.

BODE, L.E., K.H. REED, M.R. GEBHARDT,and C.L. DAY, 1969. An evaluation ofherbicide incorporation equipment. Res. Bull.946, Columbia Agric. Exp. Sta., Mo.

BUTLER, B.J. and J.C. SIEMENS. 1972. Incorporation of surface applied pesticides. Proc.24th Illinois Custom Spray Operators Training School, pp. 22-26.

HOLROYD, J. 1964. Field investigations concerning the selective phytotoxicity of Di-Allate to Avena spp. in wheat and barley.Weed. Res. 4: 142-166.

HULBERT, W.C. and R.G. MENZEL. 1953.Soil mixing characteristics of tillage implements. Agric. Eng. 34: 702-708.

LAL, R. and W.B. REED. 1976. Report onengineering study of wild oats control 1975-76.Unpublished Research Report, AgriculturalEngineering Department, University of Saskatchewan, Saskatoon, Sask.

MATTHEWS, E.J. 1970. Chloride tracer evaluation of herbicides incorporation tools. Trans.Amer. Soc. Agric. Eng. 13: 64—66.

CANADIAN AGRICULTURAL ENGINEERING, VOL. 19 NO. 1, JUNE 1977