STUDIES OF MACHINES FOR INCORPORATION OF PRE-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 implements provided deeper incorporation because of soil inversion by the discs. The tine-type implements which stirred the soil did not provide deep incorporation. The discer equipped with the Normand spray boom attachment provided a shallow or deep incorporation depending upon the position of the spray boom. The differences in incorporation capabilities of various implements will require proper selection of implement depending on the herbicide and the crop to be treated.

incorporation of fluorescent dye with a poration of granules and liquid spray. These INTRODUCTION spring tine , a rotary cultivator and a are listed below: Although not many of the herbicides in chain harrow and reported that increasing Discer —A 2.75-m Massey Ferguson discer use today are pre-emergent, the ones in use the depth and frequency of operation in with the disc size of 0.5 m spaced 0.18 m are of great significance, particularly for the creased the depth of incorporation. Mat apart. The Normand spray attachment and control of wild oats. The successful use of thews (1970) used chloride analysis for the Gandy applicator were also attached these herbicides depends on correct applica incorporation studies and reported that behind the discer. tion and incorporation. Wasted chemical, uniform incorporation in both horizontal Tandem —A 6.1-m Inter damage to crops and poor weed control can and vertical directions was obtained with national Harvestor tandem disc harrow with result from incorrect application and incor single discing, double discing and cross- the disc size of0.5 m spaced 0.19 m apart and poration procedures. discing operations. The cross-discing oper the disc gangs at an angle of 15°. Pre-emergent herbicides are available in ation did not seem to improve the distribu Field cultivator —A 6.1-m International either liquid or granular form; the most tion over the double disc operation. Butler Harvestor "vibra shank" cultivator, sweep common of these is triallate used for wild and Siemens (1972) reported incorporation size 0.23 m spaced 0.2 m apart and followed oats control. The pre-emergent herbicides of pesticides with a tandem disc harrow and by drag diamond harrows. require incorporation into the soil just after a cultivator and observed that incorporation Deep cultivator —A 3.05-m Massey application. The depth of incorporation with the tandem disc improved with faster Ferguson cultivator, sweep size 0.4 m spaced may vary depending on the kind of weed to speeds and larger gang angles and a second 0.3 apart and followed by drag diamond be controlled and the crop that is to be operation resulted in deeper and more harrows. grown. For example, trifluralin should be uniform incorporation. Incorporation with Spike tooth harrows — Three sections of mixed relatively deeply for control of wild the field cultivator was not as good as with 0.9-m-wide spike tooth diamond harrows. oats whereas a shallow incorporation is the tandem disc harrow and concentration Rod weeder —A 3.05-m Morris rod weeder. of granules appeared in rows. more satisfactory for control of green Tracer Technique foxtail. There appears to be a considerable According to Ashford (1975), a triallate difference among various incorporating im- Various tracer techniques have been used granule has to be within half a centimeter of pements with regard to their ability to to study the incorporation capabilities of a growing wild oat to have any effect. This incorporate both granular and liquid herb tillage implements. The technique used in shows the importance of a uniform ap icides to a desired uniformity and depth. this study has been described by Lai and plication and thorough incorporation of the Therefore the project was undertaken to Reed (in prep.). herbicide. Moreover, a normal application evaluate the following: Attaclay granules dyed with 0.2% ura- rate of 14 kg/ha of triallate granules when 1. The incorporation capabilities of com nine dye (sodium fluorescein) were applied incorporated to a depth of 5 cm means that mon farm implements. with a Gandy applicator at a rate of 34 one part of the herbicide has to be mixed 2. The effects of speed, mode of incorpor kg/ha, about twice the normal application with nearly 26,000 parts of the soil. ation and disc angle on the vertical rate of triallate granules. For liquid applica Various implements are used to incor distribution of granules when incorpor tion, 0.2% solution ofuranine dye in distilled porate herbicides. The common ones are ated with a tandem disc harrow. water was sprayed with different nozzles at a discer (common name for one-way disc 3. The effects of boom position, speed and rate of 112 liters/ha. harrow), tandem disc harrow, drag harrow, depth of tillage on the vertical distribu Granule and Liquid Application and cultivator. tion of the liquid when using the Nor Bode et el. (1969) studied the incorpora mand attachment on a discer. A 3.05-m-wide Gandy applicator was tion of trifluralin with various implements 4. The effects of the spout position of the used for spreading granules on the soil and reported that deeper incorporation was Gandy applicator on the vertical distribu surface at a rate of 34 kg/ha. The lateral obtained with a tandem disc harrow, while a tion of granules when mounted behind a distribution of granules from the Gandy shallow incorporation resulted from a pow discer. applicator was determined in both the lab er rotary cultivator. Hulbert and Menzel and the field. The distribution in the lab was (1953) used radioactive tracers and granules obtained from the calibration ofthe applica to study the soil mixing characteristics of EQUIPMENT AND PROCEDURES tor, while the field distribution was obtained various tillage implements and reported that by taking soil samples after applying the Description of Incorporating Implements disc harrowing followed by spring tooth granules but before incorporation. The harrows resulted in fairly uniform distribu Common farm implements used for depth of sampling was very shallow for these tion of granules. Holroyd (1964) studied the tillage operations were selected for incor samples.

CANADIAN AGRICULTURAL ENGINEERING. VOL. 19 NO. 1, JUNE 1977 TABLE I EXPERIMENTAL PLAN FOR simultaneously with the application, de by two passes perpendicular to each other THE TANDEM DISC HARROW pending upon the kind of experiment. The with a spike tooth harrow. A total of 39 STUDY depth of tillage was maintained close to 7.5 samples were taken along the middle of 1.16- cm for all the implements. However, the m width in order to avoid wheel tracks. penetration of rod weeder and spike tooth Test Speed Disc angle Mode of The procedure for extracting dye and number (km/h) (degrees) incorporation! harrows was shallower. Where necessary the determining the fluorescence level for each tillage was also carried out to the 10-cm sample has been described by Lai and Reed 1 5 16 Single depth. The speed of operation was main (in prep.). 2 8 16 Cross tained at 8 km/h. In each case, a single Data Analysis 3 8 16 Single operation was carried out for incorporation 4 8 20 Single except in the case of spike tooth harrows For a vertical distribution ofthe granules 5 8 20 Cross where incorporation was carried out by and the liquid, a total of 27 fluorescence 6 5 20 Cross cross-harrowing. readings obtained in a replicate were aver Experiments were also conducted to tSingle, single pass with harrow in the direction of aged for each soil layer. Each ofthese values granules application. determine the effects of preincorporation was transformed to the percentage of the Cross, cross-harrowing, i.e., second pass at right tillage depth on the depth of incorporation. sum of the fluorescence values of the angles to the single pass. The depths of tillage considered were 5 cm replicate. These percent values represented and 10 cm. the quantity of the granules or the liquid incorporated at various depth levels. A Tandem disc harrow TABLE II EXPERIMENTAL PLAN FOR further average of these percentages of four THE NORMAND AND THE The effects of disc angle, single vs. a replicates represented the quantity of the GANDY ATTACHMENT WITH double-cross operation, and travel speed on granules or the liquid for each soil layer THE DISCER incorporation depth were measured. The which was incorporated in that layer for a details are given in Table I. test trial. Thus, a total of 108 fluorescence Test Depth Speed Nozzle or spout Discer with Normand and Gandy attach readings were averaged for each depth level number (cm) (km/h) locationt ment for every test. The uniformity of incor The effects of the spray nozzle position poration at different depths was estimated Hor. Vert, a with the Normand attachment and the spout from the coefficients ofvariation which were position of the Gandy applicator on the Normand attachment calculated with 108 values from all the depth of incorporation were determined. In replicates at each depth level. 1 7.5 8 50 50 36° addition, the effects of travel speed and Analysis of variance and Duncan's new 2 7.5 5 50 50 36° tillage depth were included in the study. multiple range test were applied to various 3 10.0 8 50 50 36° Table 2 lists specific details. test trials at individual depth level. Similar 4 10.0 5 50 50 36° treatments were also paired for this analysis 5 7.5 8 31.5 40 55° Soil Sampling and Dye Extraction 6 7.5 5 12.5 50 65° for determining the effect ofa single variable Vertical distribution on incorporation. Gandy attachment Soil samples were taken immediately The fluorescence readings were averaged 7 7.5 8 2.5 63.5 90° after incorporation. The strip of incor over the three replicates for the lateral 8 7.5 8 15.0 63.5 90° porated land was divided into four sections, distribution of the granules and the liquid. each section thus representing one replicate. These average values for each sample were t Hor. = Horizontal position of nozzle tip or spout Three sample locations across the width of then transformed to the percentage of the opening from the discs in cm. Vert. - Vertical position of nozzle tip or spout incorporation and three along the line of sum ofall the values ofa test. This procedure opening from the lowest part of the disc in cm. travel were chosen in each section. Positions resulted in a common mean for similar a - spray angle or spout angle in degrees. of wheel tracks were avoided in taking treatments for the purpose ofcomparison of samples. Soil samples were taken at intervals distribution pattern. The range ofvalues was of 3.05 m along the line of travel. calculated as the percentage of the mean At each sample location, three samples which showed the minimum and the max Floodjet TK 2.5 and Teejet 6502 nozzles were taken adjacent to each other down to imum quantity of the granules or the liquid were used for spraying liquid for deter the depth of incorporation. Each of these at any location in the test strip. The mining their uniformity of distribution samples was divided into three parts for coefficients of variation were calculated as patterns in the lab and on the soil surface. depths of 0—2.5 cm, 2.5—5.0 cm, and 5.0— the measure of the uniformity of incor However, Teejet 65015 nozzles were used for 7.5 cm. Thus, at each location, nine samples poration. the Normand spray attachment and Flood- of approximately 16.4 cm3 of soil were jet TK 2.5 nozzles were used for the liquid collected. A total of 81 samples were taken incorporation study. The nozzles were oper for each replicate for 7.5-cm depth of ated to deliver 112 liters/ha. RESULTS AND DISCUSSION incorporation. The tracer granules and the liquid were Vertical Distribution of Granules applied in front of the . However, Lateral distribution with the Normand spray attachment and Soil samples for lateral distribution were Figure 1 shows that the best mixing of with the Gandy attachment behind the taken at three random locations along the granules to 7.5-cm depth in the soil was discer, the spray or granules were directed line oftravel. For the granular experiment, a obtained with the disc-type implements. on to the turning soil. For both granular and total of 54 samples were taken at each Similar results have been reported earlier liquid applications, a strip of land equal to location along the middle for a width of 1.6 (Hulbert et al. 1953; Bode et al. 1969; the width of the applicator (3.05 m) was m between the tractor wheels. The width of Matthews 1970; Butler et al. 1972). There used. The effective length of the exper 1.3 m between the front wheels of the MF was no significant difference in the dis imental strip was 32 m. 1150 tractor was a limiting factor. tribution between the tandem disc harrow For the lateral distribution of liquid with and the discer. Experimental Procedure Teejet 6502 and Floodjet TK 2.5 nozzles, soil Both cultivators followed by spike tooth Incorporation of granules and liquid was samples were taken after spraying the liquid harrows appeared to be quite similar in their carried out just after the application or on the soil surface and after incorporation ability to incorporate the granules. A higher

CANADIAN AGRICULTURAL ENGINEERING, VOL. 19 NO. 1, JUNE 1977 percentage of granules was found in the top 100 40.2 41.4 60.8 57.4 92.7 2.5-cm layer and a lower percentage in the DEPTH (CM) third 2.5-cm layer. This difference between cultivators and disc-type implements is 80 - 0-2.5 Y///A thought to be due to the fact that discs cause soil inversion, whereas the cultivators only

< 60 2.5-5.0 stir the soil. (r o • Another effect of secondary distribution »- z of granules was also observed with cultiva UJ 41.0 u 40 tors followed by harrows. The combined action of both the implements tends to place granules in ridges and leave furrows with few 36.6 35.4 20 — or no granules. This row effect was also observed in another experiment using tri

13.4 17.6 7.2 6.6 allate granules on Harmon oats (Lai and 2.6 0.7 Reed 1976). Butler and Siemens (1972) also TANDEM DISCER FIELD DEEP ROD observed a similar row effect with a field DISC CULTIVATOR TILLAGE WEEDER cultivator. CULTIVATOR The rod weeder caused little mixing and a Figure 1. Incorporation of granules with various implements. very high percentage ofgranules remained in the top layer of soil with only a trace reaching the third layer.

Effect of Pre-incorporation Tillage Depth 80 PRE-INCORPORATION DEPTH Figure 2 shows the percentage of gran • 5.0 CM ules mixed at various intervals of depth for 5.0-cm and 10.0-cm depths of tillage priorto 111 10.0 CM the application of granules. 60 There were nearly 22% more granules in

3 the top 2.5-cm layer where the soil was tilled Z 5.0 cm deep rather than 10.0 cm deep. This cr 40 difference reversed in both the 2.5 — 5.0-cm layer and the 5.0 — 7.5-cm layer where nearly 8% more granules were deposited for o

DEPTH (CM) the concentration of granules at various depth intervals between 16° and 20° disc Figure 3. Granule incorporation with the tandem disc harrow. angles either with a single or double pass.

CANADIAN AGRICULTURAL ENGINEERING, VOL. 19 NO. 1, JUNE 1977 SPOUT LOCATION 75.9 47.3 62.5 61.2 83.6 80 • 2.5 CM (HOR) DEPTH (CM) 80 — E3 15.0 CM (HOR) 0-2.5

60 • *.5-5.0 < SPEED 8 KM/H 37.8 o 40 - 40 - 5.0-7.5 z Ul o

31.9 34.5

20 - 26.1 15.8 5.6 4.3

TANDEM DISCER DISCER FIELD DEEP ROD

-2.5 2.5-5 5- 7.5 DISC (BOOM (BOOM CULTIVATOR TILLAGE WEEDER DEPTH (CM) BEHIND) IN FRONT) CULTIVATOR Figure 4. Granule distribution with the Gandy Figure 5. Incorporation of liquid with various implements. attachment behind the discer. Spouts positioned 63.5 cm above ground level.

BOOM POSITION BOOM POSITION (50 + 50) 36° (50 + 50) 36° BOOM POSITION 80 However, the uniformity of incorporation • 8 KM/H • 8 KM/H (50 + 31.5) 55° • 8 KM/H was improved significantly at the larger disc ~ 5 KM/H Zft 5 KM/H (50 + 12.5) 65° H 5 KM/H angles.

60 Speed of travel ^1 Increasing the speed from 5 km/h to 8 km/h provided deeper incorporation of granules when a single pass was made. Comparisons after two passes showed no difference in the depth of incorporation or in quantitity of granules deposited at various depth intervals. The uniformity of incor 20 poration was improved at the higher speed. Mode of incorporation There was little or no change in the depth of incorporation at higher speeds between a 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 single and a cross operation of the tandem DEPTH (CM1 disc harrow. The cross operation was two Figure 6. Liquid incorporation with the Normand attachment on the discer. passes at right angles to each other. The single pass at alower speed of 5 km/h resulted in a shallower incorporation. The cross operation improved the uniformity of the disc. Nearly 52% of granules were while going against the wind will result in incorporation slightly but not sufficiently to deposited in the top 2.5-cm layer at the spout nearly all the granules being deposited on justify the time and expense required for the position of 2.5 cm away from the disc in the surface. second pass. comparison to 66% for the 15-cm position. Vertical Distribution of Liquid Thus, it is evident that the granules The uniformity of incorporation was also distribution in various layers of soil is not better at the closer spout position. However, Figure 5 shows the distribution of liquid affected by normal variations in the speed, there was a difference of only 7% granules in spray for various implements at three depth disc angle, and the mode of incorporation the top 5 cm of soil between the two intervals. The distribution of liquid within when incorporated with a tandem disc positions of spout location. the soil was quite similar to that obtained harrow. However, the uniformity of incor The spout position change showed a with the granules. The disc-type implements poration was improved with the larger disc similar trend of incorporation as did the mixed to a greater depth than the cultivators angle, higher speeds, and cross operation. boom position change of the Normand or rod weeder. This confirms the results reported by Butler attachment. The spout position of 15 cm One additional method included the use and Siemens (1972). from the discs incorporated nearly the same of a Normand spray attachment for the amount of granules in the top 2.5-cm soil as discer or the one-way-disc harrow mounted Distribution with the Gandy Attachment the boom position of 50 cm for the Normand behind the disc gang. This unit directs the behind a Discer attachment. spray into the turning or moving soil thrown Figure 1 shows the percentage of the It was also observed that with a slight up by the discs. In this case about 75% ofthe granules deposited at various depth levels wind, granules were blown either toward the liquid remained in the top layer and a very for two positions of the Gandy applicator at discs or away from the discs, depending small amount reached the third layer. This the rear of the discer. Statistically, there was upon the direction of wind and the direcion method appeared to give close to the same a significant difference in the quantity of of operation. Wind velocities suitable for results as the rod weeder, but there is one granules deposited at various depth levels. liquid spray are likely not suitable for important difference. This difference is that Deeper incorporation of granules was granules application because going with the the top 1-inch layer of soil from the discer is obtained as the spouts were moved closer to wind will result in deeper incorporation, quite 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 was noticed at higher speed, increasing the OF GRANULES WITH VARIOUS IMPLEMENTS concentration of liquid in the top 2.5-cm layer at 7.5 cm tillage depth; but for 10-cm tillage depth, this trend was reversed at the Treatment Range Coefficient of % of mean variation top 2.5-cm layer although the difference was (%) less marked, with nearly 78% liquid de posited in the top 5-cm layer at 8 km/ h speed Gandy - calibration 59.5-165.4 25.4 and 81% at 5 km/h speed. The uniformity of Gandy - in the field 65.9-151.4 17.8 incorporation was better at higher speed. Cross-harrowing (2 passes) 67.0-189.2 19.8 Thus, in general, the depth of incorpor Tandem disc harrow (one pass) 61.1-154.6 20.4 ation with the Normand attachment will Discer 55.0-175.2 27.3 depend on the boom position, depth of Cultivator with harrows 55.7-207.6 35.0 tillage and the speed of travel. In most cases, the depth oftillage is adjusted to give proper TABLE IV RANGE AND COEFFICIENTS OF VARIATION IN LATERAL DISTRIBUTION seeding depth with a discer and it is seldom OF LIQUID WITH TEEJET 6502 AND FLOODJET TK 2.5 NOZZLES that the seeding depth is the same as the tillage depth. So when applying and incor Treatment Range Coefficient of porating triallate while seeding, precautions % of mean variation must be taken to avoid deeper incorporation (%) of chemical in order to prevent any crop damage. Teejet 6502 Calibration 62.1-120.7 17.3 Lateral Distribution of Granules Before incorporation 60.1-141.7 18.9 After incorporation Table 3 shows the range ofthe amount of by cross-harrowing 71.9-192.5 25.3 granules expressed as the percent of the Floodjet TK 2.5 mean over the sampling width of 1.6 m, Calibration 51.6-157.0 31.3 along with the coefficient of variation for Before incorporation 52.0-208.9 30.2 each treatment. From the comparison ofthe After incorporation coefficient ofvariation, the field distribution by cross-harrowing 47.3-177.3 41.0 of the Gandy applicator was more even than that in the lab. This may be the result of the granules being bounced and dispersed more rod weeder is considerably drier under most decreased successively at each boom posi evenly when falling to the ground. The light circumstances. This difference in moisture tion. wind always present during the field exper could have a profound effect on the activity Thus, the position of the boom was very iments may also have helped in making the of the actual chemical utilization. important in determining the distribution of distribution more even. liquid and the depth of incorporation. For Comparing the distribution ofthe Gandy Distribution with the Normand Attachment shallow incorporation it is important to applicator in the field with the distribution on a Discer maintain the boom in the further away of the four implements, their order may be Figure 6 shows the percentage of liquid position. It is also interesting to note that the arranged according to the degree of uni found at various depths for different treat closest position resulted in incorporation formity as follows: cross-harrowing, tandem ments with the Normand attachment on the nearly equivalent to cross operation with the disc harrow, discer, cultivator with harrows. discer. Statistically, a highly significant tandem disc harrow. The minimum and maximum number of difference was observed in the quantity of granules at any location depended on the Depth of tillage liquid deposited at each depth interval for all applicator and incorporation implement. As Increasing the tillage depth of 7.5 cm to the treatments. shown in Table 3, the range varied from 55% 10 cm reduced the amount of liquid depos to 207.6% of the average value after incor Boom position and spray nozzle ited in the upper layer. At a speed of 8 km/h, poration, while the range for the applicator Bringing the boom closer to the discs nearly 94% of the liquid was located in the was 65.9 — 151.4 % before incorporation. top 5 cm when tilling 7.5 cm deep compared increased the concentration of liquid at This indicated the variation in concentra lower depth intervals, thus increasing the to 78% when tilling 10cm deep. As expected, tion of granules which at the lower concen depth of incorporation. When the position the differences in the upper layer resulted in tration may not be sufficient for controlling of the spray boom of the Normand attach similar differences at the lower levels. wild oats, and at higher levels may damage ment was changed, the spray angle was also At a slower travel speed of 5 km/h, the the crop. The range ofconcentration nearest changed. Three different horizontal posi difference was less marked with 86% of the to that of the Gandy attachment was tions of the boom in this experiment resulted liquid located in the top 5-cm layer while obtained with the tandem disc harrow, in threee different angles of spray. The tilling at 7.5-cm depth and 81% when tilling followed by the discer, cross-harrowing and percentage of liquid incorporated at differ at 10-cm depth. the cultivator with harrows. Although the ent depth intervals at these positions and the Although the depth of incorporation distribution of granules was more even with angles of spray are shown in Figure 6. increased with the depth of tillage, the incorporation by cross-harrowing, the range Comparing the concentration of liquid in uniformity of incorporation decreased and of granules was higher than that of the the top 5-cm layer, nearly 94% was incor was much less uniform with the greater tandem disc harrow and the discer. This may porated at the boom position of 50 cm, 83% depth of tillage. have been caused by the concentration of at 31.5 cm and 76.8% at 12.5 cm. The Speed of travel granules in the rows. tendency of the liquid distribution among Little or no difference was observed in three depth intervals was toward a greater the concentration of liquid at various depth Lateral Distribution of Liquid amount of liquid at lower depths as the intervals between 5 km/h and 8 km/h speed The objectives behind these trials were to boom was brought closer to the discs. of travel either at 7.5-cm or 10-cm tillage compare distribution patterns of liquid at However, the uniformity of incorporation depth. However, a shallower incorporation various stages of nozzle operation, i.e.,

10 CANADIAN AGRICULTURAL ENGINEERING, VOL. 19 NO. 1, JUNE 1977 TEEJET 6502 NOZZLE other) (2) rod weeder, (3) tandem disc herbicides requiring shallow incorporation, - CALIBRATED PATTERN C.V.= I7.3 harrow, (4) one-way disc harrow or discer, the depth oftillage and position ofthe spray - BEFORE INCORPORATION C.V. = 18.9 (5) light duty cultivator with harrows and boom is important. - AFTER INCORPORATION C.V. = 25.3 (6) heavy duty cultivator with harrows. The discer with a rear-mounted attach In terms of depth of incorporation the ment for granule application resulted in descending order was as follows. (1) tandem satisfactory incorporation provided the disc harrow, (2) discer, (3) light duty cul spouts were positioned properly or the tivator, (4) heavy duty cultivator, (5) har granules were directed correctly. The posi rows, and (6) rod weeder. tion determined the depth of incorporation The disc-type implements provided if there was no wind. Moderately windy deepest incorporation because the soil was conditions could result in an erratic incor inverted or turned over by the disc action. poration, since the granules are very easily •*f — V- MEAN Tine-type implements which stirred the soil blown about. did not tend to give deep incorporation. The Uniformity of the application of liquid wider the spacing of the tines or shanks, the herbicides from spray nozzle onto the soil less uniform will be the results. The rod and granules from granule applicators is weeder apparently did little as far as in important. The lateral distribution patterns corporation was concerned, with over 80% from individual nozzles and granular ap

h DISTANCE BETWEEN WHEELS - of liquid or granules remaining in the top plicators in the laboratory were similar in .-I layer. shape to the patterns of the lateral distribu IiiiiiIiiiiiJi The vertical distribution of granules was tion in the soil after incorporation by 60 40 20 CL 20 40 60 influenced considerably by the depth of pre- harrows. In most cases the distribution after DISTANCE FROM CENTRE (CM) incorporation tillage. Doubling the depth of incorporation by harrows was less uniform cultivation resulted in nearly 22% fewer than the distribution before incorporation. Figure 7. Lateral distribution of liquid with granules in the top 2.5-cm layer. Teejet 6502 nozzle. These results indicate that if granular herbicides are incorporated with spike tooth ACKNOWLEDGMENTS harrows, the depth of loose soil prior to calibration, field application before incor The authors wish to acknowledge the assis poration and after incorporation. The sim incorporation influences the depth of in tance and financial support provided by the ilarity of patterns and degree of dispersion corporation and the distribution of gran Engineering Research Service, Research Branch, were estimated from the range expressed as ules. It is expected that the results would be Agriculture Canada, Ottawa, through a DREAM the percent of mean value and coefficients of similar with the liquid form ofthe herbicide. project. The project reported here was a part of variation which are given in Table 4. The tandem disc harrow provided the the contract for the years 1974-76, awarded by the The range of variation ofchemical in the deepest incorporation with only one pass Science Contracting Branch, Department of sampling width increased after incorpora over the field. There was practically no Supplies and Services, Ottawa, Ontario. tion by cross-harrowing, but there is a change in the depth of incorporation (ver tical distribution) by the second pass or similarity in the distribution patterns, as ASHFORD, R. 1975. Triallate granule spacing operation with the tandem disc harrow, but shown in Figure 7 for the Teejet 6502 nozzle. effect on oat. Weed Sci. 23: 470-472. The peaks seem to occur at relatively the uniformity of incorporation was improved. BODE, L.E., K.H. REED, M.R. GEBHARDT, same positions for the calibrated pattern and Speed oftravel and disc angle ofthe tandem and C.L. DAY, 1969. An evaluation of the field patterns. Stirring the top soil by disc harrow likewise had little effect on the herbicide incorporation equipment. Res. Bull. cross-harrowing did not seem to eliminate depth of incorporation. Increasing the speed 946, Columbia Agric. Exp. Sta., Mo. the original applied pattern. However, the of travel and the disc angle resulted in more BUTLER, B.J. and J.C. SIEMENS. 1972. Incor uniformity decreased, as indicated by the uniform incorporation. Since higher speeds, poration of surface applied pesticides. Proc. 24th Illinois Custom Spray Operators Train increased coeffcient of variation. Since the larger disc angles, and double operation all tend to pulverize the soil, serious problems ing School, pp. 22-26. distributions of chemical between the pat HOLROYD, J. 1964. Field investigations con terns obtained before incorporation and with soil erosion could develop. Too high a cerning the selective phytotoxicity of Di- after incorporation are similar, it is best to speed will also cause soil ridging. Allate to Avena spp. in wheat and barley. apply the chemical uniformly over the field. The discer equipped with the Normand Weed. Res. 4: 142-166. HULBERT, W.C. and R.G. MENZEL. 1953. spray boom attachment could be positioned Soil mixing characteristics of tillage imple to provide shallow or deeper incorporation CONCLUSIONS ments. Agric. Eng. 34: 702-708. nearly equivalent to two operations with the LAL, R. and W.B. REED. 1976. Report on The results from the soil incorporation tandem disc harrow. The deeper incorpora engineering study ofwild oats control 1975-76. studies indicated substantial differences in tion was less uniform than the shallow Unpublished Research Report, Agricultural the incorporation capabilities of various incorporation. The higher speed of travel Engineering Department, University of Sas machines as to both depth and uniformity. tended to give shallower but more uniform katchewan, Saskatoon, Sask. In terms of uniformity of incorporation, the incorporation. As with other implements, MATTHEWS, E.J. 1970. Chloride tracer evalua the depth of incorporation is controlled to tion of herbicides incorporation tools. Trans. descending order was as follows: (1) har Amer. Soc. Agric. Eng. 13: 64—66. rows (two passes perpendicular to each some extent by the depth oftillage; for those

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