In the last few years, primary producers have been encouraged to re-evaluate their methods of crop production. The movement to extended rotations and direct seeding has successfully demonstrated the viability of alternative cropping practices. The use and adoption of air seeders have further encouraged the trend toward low disturbance seeding. In the past few years, direct seeding in Saskatchewan has increased to 8 M acres, with the potential to rise to 23 M acres in the future.
In general, producers using a direct seeding system continue to band their fertilizer inputs in a separate operation prior to seeding. However, recent innovations in the design and manufacture of openers have generated interest in single pass seeding and fertilizer operations. Because of the economic advantages, many producers are interested in using anhydrous ammonia (NH3) as their nitrogen fertilizer.
This paper examines recent studies conducted in western Canada wherein NH3 application has been coupled with seeding in a single pass operation.
Although numerous seed/fertilizer openers are commercially available, evaluating every opener is beyond the scope of this, or any study; therefore we chose to limit our evaluate to four systems of NH3 application. The systems were selected because they are representative of the style and type of openers a producer can obtain commercially and are believed to offer the necessary spatial separation of seed and NH3.
Experiments were conducted in 1994 at three locations within the Dark Brown and Black soil zones. All openers were evaluated with NH3; in addition, granular urea was applied with two openers as a fertilizer source comparison. Nitrogen fertilizer sources were applied at rates of 0, 35, 70 and 105 kg N/ha (0, 31, 62 and 94 lb N/ac). Attempts to equalize seeding depth with each opener were made at seeding. All trials were established in stubble cropping situations. Spring wheat was grown as the test crop at all sites. Seed was distributed to five shanks spaced at 30 cm (12"). The following openers were evaluated in the testing:
1) Sweep Wing Tip System - supplied by D. J. Manufacturing, this system used a 35 cm (14") shovel in which NH3 tubes are split and extended to the wing tip section of the shovel. Anhydrous tubes are attached to every second shank; therefore this system simulates a midrow fertilizer application. The NH3 is applied at the same depth as the seed. Shovels are equipped with Froc boots which act to scatter the seed creating a seedrow approximately 4.5 cm (3") wide.
2) Sweep/Froc Seedplaced System - identical to the above but instead of applying NH3, granular urea was applied with the seed through the Froc boot on each shank. This acted as a practical comparison to the wing tip system in that both are easily adaptable for producers interested in seeding and applying fertilizer in a single pass system.
3) Flexi-Coil Stealth Side Band Knife - a relatively narrow side band knife that placed the fertilizer 3.75 cm (1.5") below and 3.75 cm (1.5") to the side of the seed.
4) Flexi-Coil Stealth Side Band Knife - identical to the above but granular urea was applied in this treatment.
5) Gen T200 Side Band Knife - a heavier, wider knife than the Flexi-Coil, this knife placed the fertilizer 5 cm (2") below and 5 cm (2") to the side of the seed.
6) Coulter Opener - 50 cm (20") fluted Super 900 Flex Coulters were supplied by Blue Jet (Thurston Manufacturing) and were mounted between every second shank, thereby creating a midrow fertilization system, NH3 was injected directly into the furrow created by the coulter. This system allowed the NH3 to be injected at depths below seeding depth.
Grain yield results indicate that no particular opener was superior from location to location. The effect of each opener or system, averaged over three sites, is illustrated in Figure 1.
In general, wheat yields increased with all openers as fertilizer rates were increased. Yields obtained with the Sweep/Froc urea application tended to be lower than other treatments. This observation was heavily influenced by the large negative effect obtained with this treatment at the Dark Brown soil location. At this site, soil moisture conditions restricted seed and fertilizer scatter through the Froc boot such that considerable plant stand reductions occurred. Further, yields tended to decrease with the Flexi-Coil urea treatment as rates were increased from 70 to 105 kg N/ha. In this case, it is possible that the concentration of ammonia within the narrow fertilizer band was still high enough to injure young growing plants. All other opener/system NH3 applications were similar in yield response. The average influence of opener across all three fertilizer application rates is shown in Figure 2.
A number of observations can be made about the various openers. With the Sweep system, NH3 losses were reduced by using 20 cm (8") wide packing wheels behind each opener. Narrow packing wheels with this system did not adequately seal the injection area. The sweep system may have limitations where wet soil situations occur. In such situations, the physical disturbance which helps bind the gaseous NH3 to soil particles is reduced and the soil seals poorly. As a consequence gaseous losses could be high. With heavy textured moist soils the tillage action of the shovels produces cloddy conditions resulting in less than desired seedbed conditions and favoring potential volatilization losses. Additionally, high soil disturbance on light textured, or relatively dry soils may lead to reduced seedbed moisture and gaseous nitrogen losses. Although this system is easily adaptable to air seeders and possible the cheapest to outfit, management skills will be crucial to achieve successful results.
With both side band knives, gaseous losses were visually evident at the high fertilizer rates. At lower application rates, visible losses were not apparent; therefore it appears that the soil was able to effectively bind the NH3. At high rates the volume of product injected apparently surpassed the soil's retention capacity. Losses occurred immediately along the back of the knife. These gaseous losses occurred so rapidly that inclusion of shank mounted packers may not seal the injection trench quickly enough to prevent the losses. Migration of high concentrations of NH3 upward and into the seed row is also a concern. It may be that a Cold-Flo conversion system wherein the NH3 is injected as a liquid under low pressure may alleviate or reduce gaseous product losses. Fan speed on an air seeder will also influence the performance of side band openers. If air flow is too high seed depth may vary and seed may be blow into the fertilizer row and severely reduce the crop stand. Seed movement under these conditions will be influenced by the size of the seed trench created and the spatial separation of the seed and fertilizer rows.
The coulter system appeared to work well; however, under the conditions of our experiment, problems occurred with straw and soil accumulation between the coulters and the shanks under heavy trash conditions. This plugging could cause problems in direct seeding systems; therefore design of coulter mountings must be given careful consideration. Other limitations to the coulter system is that under very heavy trash conditions the coulters may not be able to successfully cut through residue material. Straw that is "hairpinning" will allow a channel for volatilization losses. The use of coulters will also be adaptable only to land that is stone free.
Openers or systems were not found to differ with respect to their influence on protein content or seed quality.
Saskatchewan Wheat Pool has also conducted demonstrations with the following openers; Gen 200 T2 x 2 Paired Row Opener, Flexi-Coil Stealth LS Double Shoot Paired Row Opener, Poirier Double Shoot Opener, Peacock Precision Seeder, Farmland Paired Row / Back Swept Knife, Morris Edge-On Paired Row Opener and the Buffalo Seeding System. Canola and wheat have been successfully grown, without loss of yield, at rates of anhydrous ammonia up to 105 kg N/ha (94 lb N/ac).
Producers attempting to convert openers to apply NH3 should be conscious of the potential for boot or shank freezing. Anhydrous ammonia has a boiling point of -330C, therefore metal coming into contact with vapour will freeze. Under certain conditions this freezing can cause a build up of frozen soil on the boot resulting in greater disturbance, a poor seedbed and higher draft requirements. To minimize or prevent boot freezing a plastic or rubber inserts or foam insulation spray should be used to separate NH3 hoses or tubes and metal surfaces of the opener.
In 1994 the Alberta Farm Machinery Research Centre (AFMRC) conducted three individual trials with NH3 at seeding. Anhydrous ammonia and granular urea were applied at rates of 0, 56, 112 and 168 kg N/ha (0, 50, 100 and 150 lbs N/ac). Trials were established in 1994 on heavy clay, clay loam and sandy loam textured locations seeded with both wheat and canola. Cultivator shank spacing was 25.4 cm (10"). All trials were established in a randomized factorial design.
Openers included in the test are as follows:
1 & 2) Flexi-Coil Stealth openers equipped with (a) shallow and (b) deep fertilizer points, placed the fertilizer between and below two paired seed rows.
3) Farmland Argo 10.2 cm (4 ") chrome sweep and backswept knife. Fertilizer is placed in a furrow cut by the backswept knife and seed is broadcast under the sweep.
4) Gen side band knife placed the fertilizer 5 cm (2 ") below and 5 cm (2 ") to the side of the seed furrow.
5) McKay Dart 30.5 cm (12") sweep with anhydrous split to the wing tip sections, equipped with a Farmland Agro seed splitter, placed seed in paired rows between the NH3 injection positions. For comparable granular urea treatments a New Noble paired row boot was used which placed the urea in a similar pattern to the NH3.
Findings suggest that fertilizer source had little effect on the emergence of wheat and canola. Emergence differences occurred on the light textured, sandy loam, site. At this location NH3 application reduced the emergence of wheat and urea reduced the emergence of canola. These results suggest that soil texture exerted greater effect on plant emergence than did the fertilizer source. The influence of fertilizer type on emergence of wheat and canola is shown in Figure 3.
The influence of the opener on emergence tended to vary from one site to another. However, the Sweep and Gen openers produced a slightly more consistent and uniform emergence across the three textural types. There was a general trend towards lower emergence with increasing rates of applied fertilizer and these differences were statistically significant in half of the tests. All trials were conducted on irrigated fields with ideal seedbed moisture which limited potential stand reductions at high fertilizer application rates.
Canola yield was not influenced by the type of fertilizer applied; both NH3 and granular urea performing in a similar manner. Wheat yields were influenced by fertilizer type in an inconsistent fashion. The use of NH3 resulted in higher yields on the medium textured site whereas urea resulted in higher yields on the light textured site. Yields of both crops are shown in Figure 4.
On average, yield increased as fertilizer rate increased. Yield responses to fertilization varied both between locations and crops. Yields were not adversely influenced by high rates of either granular urea or NH3.
This study also attempted to quantify potential NH3 losses to the atmosphere during seeding. Sample tents were positioned over the 168 kg/ha NH3 application treatment on the medium textured site and air samples taken one hour after fertilization were analyzed for ammonium. Table 1 outlines the average NH3 losses measured.
Table 1. Percent Loss of Anhydrous Ammonia in a One Hour Period After Application
| Opener |
% Loss
|
| Flexi-Coil Shallow |
0.34
|
| Gen |
1.15
|
| Flexi-Coil Deep |
2.38
|
| Sweep |
4.13
|
| Farmland |
7.45
|
Percentages shown in Table 1 reflect the loss of NH3 from the soil during a one hour period immediately after fertilizer application. This is a measure of passive NH3 loss. It did not account for potential losses immediately during application, so it is likely that total NH3 losses were underestimated. Nevertheless, results do indicate differences between openers. It should be stressed that these results reflect only the findings from a single site and single fertilizer application rate. The results should not be used to make broad based assumptions as to the efficacy of any particular opener. Appropriate packing systems designed to compliment a particular opener may enable NH3 to be effectively applied with minimal gaseous losses.
In 1995 AFMRC repeated a series of opener and fertilizer trials at nine sites throughout Alberta. Crop types evaluated included canola, wheat and barley, urea and anhydrous ammonia were applied at increasing increments to 168 kg N/ha (150 lb N/ac). Openers evaluated included the Barton No-Till Double Shoot Opener, Bourgault's Double Shoot (Side Band) and Mid Row Opener systems, Flexi-Coil's Side Band Double Shoot and LS Paired Row Double Shoot Openers, Gen Side Band and Paired Row Openers, Key Ag Ventures Backswept Knife systems (4 and 7" chrome), Melranda Zero Till system, Morris Paired Row Double Shoot Opener, Poirier Double Shoot Opener and Sweep systems.
In general, no statistical differences were apparent between urea and anhydrous ammonia at most sites. In some cases (depending on site and soil conditions) emergence and yield were reduced with anhydrous ammonia, yield reductions were attributed to losses of anhydrous ammonia during and after seeding. Although openers varied slightly from location to location all were found capable of applying anhydrous ammonia in a single pass system.
Four research trials with NH3 at seeding were conducted in 1994 by Ag-Quest, Inc., in southern Manitoba. Trials evaluated NH3 and granular fertilizer at application rates of 50 and 100 kg N/ha (45 and 89 lb N/ac). Anhydrous ammonia was applied through a Cold-Flo system and wheat was planted in all trials. Shank spacing was on 25 cm centers. Openers evaluated in the tests include:
1) 30 cm (12") McKay sweeps with a D. J. Wing Tip injector system as previously described.
2) Sweeps with Farmland backswept knives which placed the seed in paired 5 cm (2") rows, fertilizer was placed midrow 5 cm (2") below the seed.
3) Anderson Paired Row opener which placed the seed in two 5 cm (2") rows, fertilizer was placed midrow at a depth of approximately 6.3 cm (2.5").
4) Farmland Paired Row system which placed seed in two 3.8 cm (1.5"), fertilizer was applied midrow 5 cm (2") below the seed.
5) Dutch side band knife which placed the fertilizer 3.2 cm (1.25") to the side and 2.5 cm (1") below the seed.
6) Swede side band knife which placed the fertilizer 2.5 cm (1") to the side and 2 cm (0.75") below the seed.
The influence of openers using NH3 and granular urea, averaged across the two fertilizer treatments, is shown in Figure 5.
Unlike previously described findings, these results suggest that NH3 is inferior to granular urea in a single pass seeding/fertilizing operation. Anhydrous ammonia and urea yielded equally well only at the 100 kg N/ha (89 lb N/ac) rate applied through the Anderson paired row system. Yields achieved from urea surpassed those obtained from NH3 in all other treatments. Within each fertilizer application rate, urea produced approximately 150 kg/ha (2.2 bu/ac) more grain than NH3. The reasons for these differences between fertilizer sources are not apparent. However, it was observed that some NH3 treatments produced variable crop height patterns within fertilizer treatments. This suggests uneven nitrogen distribution with NH3 applications. Several possible scenarios may have occurred.
When NH3 was released from the metering devise into the manifold, lack of distribution line pressure may have caused irregular distribution patterns. It is also possible for the vapor pressure at the liquid surface of the supply tank to fall below the vapor pressure of the NH3 flowing to the meter, resulting in lower than anticipated delivery rates from the meters. If these, or additional factors occurred, then the application rate of NH3 may have been less than that of granular urea. Irregularity between the granular urea and NH3 application rate may account, in part, for the yield differences obtained.
A series of NH3 trials were conducted across Saskatchewan and Alberta using the Conserva Pak seeding system in 1994. These trials were a cooperative effort between Conserva Pak, Head & Associates, Agriculture Canada and Westco. Trials evaluated varying rates of NH3 and granular urea on cereals and canola. Anhydrous ammonia was applied through a Cold-Flo system. The Conserva Pak is an integrated seeding system whereby seed and fertilizer is applied through a narrow knife double opener system with on-shank packing. In all trials, fertilizer was applied 2.5 cm (1") to the side and approximately 4 cm (1.5") below the seed row.
The effect of fertilizer application on plant stand of wheat and canola is shown in Figure 6. Wheat stands were reduced marginally with the use of NH3 by approximately 5% across the seven sites. Significant differences in wheat seedling numbers due to NH3 application occurred at two of the trials. In general canola plant stands were not influenced by the form of fertilizer applied. Significant differences occurred at only one location, where granular urea reduced seedling numbers to a greater extent than NH3. With wheat there appeared to be a slight decrease in seedling numbers as the rate of fertilizer application increased. Fertilizer rate had little overall effect with canola.
Yield results for both wheat and canola are shown in Figure 7. No significant differences in grain yield of wheat occurred between NH3 and urea fertilizers. Average grain yield response to 112 kg N/ha (100 lb N/ac) was 33% for urea and 34% for NH3. Canola yield response to fertilizer source was similar to wheat. On average, both fertilizer sources had an equal influence on canola yield. Lower yields resulting from NH3 application occurred at one site. With both crops, it appears that fertilizer rate had a larger effect than did fertilizer form.
Nitrogen fertilizer sources were generally not different with respect to dry matter, harvest index, N uptake or N use efficiency.
Anhydrous ammonia has been in use in western Canada since the early 1950's. The appeal of anhydrous ammonia is due to its low cost (approximately 20% less than urea), high analysis, and availability. Traditionally, anhydrous ammonia has been banded with narrow knife openers either in the fall or spring. Until recently it was recommended that seeding be delayed for 5 to 7 days after spring applications. Planting now frequently occurs immediately after application and with innovations in seeding technology, simultaneous seeding and fertilizing operations with anhydrous ammonia are being attempted. Direct seeding with NH3 application will be successful only as long as sufficient separation of seed and NH3 is achieved.
This form of operation is prone to risk but, as the above studies indicate, is possible if a number of factors comply. The technology is still developing, and for those who are awaiting the "perfect" opener the wait may indeed be long. It is unlikely that any particular opener or system will be found that consistently is superior and works in all conditions. More likely numerous openers will be able to lend themselves to ammonia application at seeding. These openers will have to be matched to a particular soil texture and to suitable soil moisture, be adaptable to the producers seeding equipment and be matched with an appropriate packing system. Packing systems are an area which warrants examination. In Saskatchewan Wheat Pool's preliminary investigations we noted that narrow tire packers were a poor match when using a sweep system. It is possible that anhydrous ammonia retention will only be effective under a variety of soil conditions, when coupled with a suitable packing system which will quickly and effectively seal the injection zone.
The number and style of openers are in various stages of evolution and development. Consequently, researcher's will not be able to evaluate and compare all commercially available openers. Design and/or modifications may assist in reducing potential NH3 losses during application or minimize potential seedling damage. Modifications could include sealer plates on the back of openers which might help restrict upward migration of gas. Alternatively, modification to the shape of the injection orifice could be used to modify the shape of the retention zone.
Future research should expand to landscape scale studies and include variable application rates to match field topography.
The author would like to acknowledge the assistance and cooperation of Mr.'s Norm Flore and John Harapiak, Westco, Jim Halford, Conserva Pak Seeding Systems, Keith Head, Head and Associates Ltd., David Rourke and Andrew Hargrave, Ag-Quest Inc., Robert Maze, AFMRC and Dr. Adrian Johnston, Agriculture Canada, in providing the necessary material for the preparation of this paper. Readers are directed to the following reference material for additional information not included in this paper.
Maze, R., L. Papworth, A. Pickard, B. Metzger and K. Boras. 1994. Effectiveness of double shoot openers for applying anhydrous ammonia and urea while seeding wheat and canola. Research project RL0394 report, Alberta Farm Machinery Research Centre.
Johnston, A., G. Lafond, J. Harapiak and K. Head. 1995. Response of wheat and canola to side banded anhydrous ammonia. In: Proceedings of the 1995 Soils and Crops Workshop (in print), University of Saskatchewan, Saskatoon, Saskatchewan.