Published online 12 March 2007
Published in Agron J 99:489-493 (2007)
DOI: 10.2134/agronj2005.0295
© 2007 American Society of Agronomy
677 S. Segoe Rd., Madison, WI 53711 USA
Economic Analysis
Economic Value of Polymer Seed Coat for Fall-Seeded Canola
B. M. Upadhyaya,
E. G. Smithb,*,
G. W. Claytonb,
K. N. Harkerc,
J. T. O'Donovanc and
R. E. Blackshawb
a Agriculture Financial Services Corporation, 5718 56 Ave., Lacombe, AB, Canada T4L 1B1
b Agriculture and Agri-Food Canada, Lethbridge Research Centre, P.O. Box 3000, Lethbridge, AB, Canada T1J 4B1
c Agriculture and Agri-Food Canada, Lacombe Research Centre, 6000 C and E Trail, Lacombe, AB, Canada T4L 1W1
* Corresponding author (smithel{at}agr.gc.ca)
Received for publication October 24, 2005.
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ABSTRACT
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Applying a polymer seed coat (PSC) to canola (Brassica napus L. and B. rapa L.) seed could be economically beneficial for dormant fall seeding. Field trials at three locations and across 3 yr were used to evaluate the effect of seeding date, use of a PSC, and canola cultivar on crop yield and net returns. The net returns were used to estimate the economic value of using a PSC for three locations, two seeding dates, and four canola cultivars. Net returns differed across locations, and cultivar differences occurred in one of the three locations. Net returns were higher for late-fall seeding, compared with early-fall seeding, with or without the use of a PSC. The value of a PSC was generally positive for early-fall seeding and negative for late-fall seeding. However, at a location prone to midwinter mild spells during which seed germination could occur, the PSC generally had no value. Despite the PSC having a positive value for early-fall dormant seeding, its potential use will be limited because early-fall seeding with a PSC had lower net returns than late-fall seeding without a PSC.
Abbreviations: PSC, polymer seed coat
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INTRODUCTION
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CANOLA IS AN IMPORTANT CROP in western Canada and increasingly in the northern Great Plains of the USA. Production area averaged 4.6 million ha during the past decade in Canada (Canola Council of Canada, 2005), and increased to 470 000 ha in 2005 in the USA (USDA, 2006). Canola is produced primarily for oil, though protein meal is a coproduct. The oil competes with other oil crops within the vegetable oil complex. Canola production systems research is ongoing, with the goals of increasing its competitiveness with other oil crops, increasing returns from production, and expanding production into nontraditional regions such as the semiarid region of western Canada and the northern Great Plains of the USA.
Time of seeding is an important canola production management factor. In Montana, seeding from late March through mid April was found to be optimal, and some genotypes performed better with early seeding (Chen et al., 2005). In western Canada, early seeding (late April–early May) was found to be the most profitable time of seeding (Upadhyay et al., 2005). Desirable effects of early-spring seeding include the potential to utilize available early-spring moisture and to progress past the reproductive growth period before the onset of summer heat stress (Chen et al., 2005; Clayton et al., 2004b). Fall dormant seeding is a seeding option where seeding is done late in the fall with the expectation the seeds will not germinate until the following spring. Fall dormant seeding was found to have a productivity advantage over normal spring seeding (Johnston et al., 2002; Kirkland and Johnson, 2000), but the benefit was not consistent across locations and time (Johnson et al., 2004). Even if there is no productivity benefit of fall seeding, there could be an economic benefit from spreading some of the spring workload to late fall. However, fall seeding of canola has been found to be financially more risky than spring seeding (Upadhyay et al., 2005; 2006). The risk was mainly due to reduced yield from low plant density caused by premature germination before winter or during warm winter periods, or from early-spring frosts.
Treating canola with a PSC could eliminate premature germination of dormant fall-seeded canola (Johnson et al., 2004). The water-impervious and freeze-sensitive PSC controls fall germination of canola by absorbing water into its polymer structures, blocking it from the seed. When the soil freezes, the water absorbed by the PSC crystallizes, creating microfractures. These microfractures allow seed to soil and water contact as the soil temperature warms in the spring, advancing germination. However, a PSC can reduce or delay germination, especially if soil moisture is limiting in the fall and spring (Willenborg et al., 2004). A short delay in spring germination could be advantageous for avoidance of late frosts, but if delayed too long, any advantage of early emergence is foregone.
Studies have evaluated a PSC to allow early-spring planting, taking advantage of longer-season varieties and reducing yield loss from late planting due to weather delays. Dillon et al. (2001) estimated the value of a PSC under variable rate technology and different levels of risk aversion for a representative farm in Kentucky growing corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and wheat (Triticum aestivum L.). Archer and Gesch (2003) estimated the value of a PSC for a representative farm in the northern Corn Belt. These studies used simulated data from biophysical models. The economic value of a PSC was found to be higher for soybean than corn, and higher for farmers with high risk aversion. Field studies using a PSC on corn in Iowa (Pecinovsky et al., 2006) and South Dakota (Berg et al., 2006) found no yield advantage from using a PSC.
There have been studies to determine the productivity impact of applying a PSC to canola (Clayton et al., 2004a; Johnson et al., 2004), and the economic benefit of allowing early-spring planting of some other annual crops (Dillon et al., 2001; Archer and Gesch, 2003; Berg et al., 2006). However, the economic value of applying a PSC to different herbicide-tolerant canola cultivars for fall dormant seeding has not been determined. The objective of this study was to determine the value of using a PSC for selected herbicide-tolerant canola cultivars at two times of fall dormant seeding in western Canada. The value of applying a PSC was based on the additional expected net returns obtained with the use of a PSC.
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MATERIALS AND METHODS
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This study was based on canola field experiments designed to evaluate the impact of seeding decision timing. The experiments were conducted at Lacombe (1999–2001), Beaverlodge (1999–2001), and Lethbridge (2000–2001), Alberta, Canada. Experiments were situated on different plot areas each year following spring wheat or barley (Hordeum vulgare L.). A randomized complete block design with four replicates was used for the experimental treatments. Treatments included four different herbicide-tolerant cultivars, four times of seeding, and the presence or absence of a PSC for fall seeding. The cultivars were glyphosate-tolerant ‘DK 3235’, glufosinate-tolerant hybrid ‘InVigor 2153’, open-pollinated ‘Exceed’, and imazethapyr-tolerant ‘45A71’. The seeding times were early fall (8–23 October), late fall (25 October–21 November), early spring (19 April–3 May), and traditional normal spring (3–24 May). Actual seeding date varied by location and year. The PSC was required only for fall seeding, and as a result this analysis used the two fall seeding dates. The two PSC treatments for both early- and late-fall-seeded canola were "with PSC" and "without PSC." All plots were maintained through to harvest, regardless of the plant density. Plot sizes were 3.6 x 15 m at Lacombe, 3.6 x 20 m at Beaverlodge, and 2 x 6 m at Lethbridge. Extender (Grow Tec Coatings, Inc., Edmonton, AB, Canada), a trade name for the PSC that is patented and marketed in western Canada (Zaychuk and Enders, 2001), was used for the "with PSC" treatments. Yield was assessed at maturity for each plot. Whole plots were swathed then harvested in the field by a plot combine. Yields were standardized to 10% moisture. Additional details of the experiment are described in Clayton et al. (2004a, 2004b).
Net returns were determined as the returns to land, fixed machinery, and management. For a location, the net return (
i,t) from a hectare of canola with treatment i in year t was the difference between gross return and specified production costs:
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where p = a 5-yr average canola price; yi,t = the canola yield for treatment i in year t; w = the unit cost of the PSC to treat the seed; PSCi,t = the quantity of PSC required per ha, based on the seed rate; and oci,t = all other production costs.
The price of canola varies across time, as do oil prices in the world oilseed complex, so a 5-yr average canola price was used in the analysis. The other production costs (oc) included costs for seed, fertilizer, herbicides, insecticides, operating machinery, marketing, crop insurance, and interest (Table 1) (Alberta Agriculture, Food and Rural Development, 2003, 2004, 2005; Canola Council of Canada, 2000). All input costs, except operating machinery and crop insurance, varied by treatment and year because of different input amounts. The marketing cost involved transporting the grain from farm to market, and varied directly with quantity harvested. Fall applied inputs were charged 5% per annum interest for the 6-mo period until spring to account for the difference in the time value of money between fall- and spring-applied inputs.
Statistical Analysis
Significance differences in net return for the three locations were determined using the PROC MIXED procedure in SAS (SAS Institute, 2005). The year and replications were treated as random variables. Locations were analyzed separately. Significant differences were determined by LSD (P = 0.05).
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RESULTS AND DISCUSSION
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The significance of treatments and treatment interactions on net returns for each location were reported in Table 2. The only significant interaction was seeding date by PSC, and only for the Lacombe and Beaverlodge sites. No interaction terms were significant for the Lethbridge site. There was a significant cultivar effect for Beaverlodge. Seeding date was significant for all three locations. The use of a PSC was significant for Lacombe and Beaverlodge. Subsequent reporting of results for treatments was done for the significant treatments and treatment interactions.
Average net returns for dormant fall seeding of canola were highest at Lacombe (CAN $178 ha–1), lowest at Beaverlodge (CAN –$162 ha–1), and at Lethbridge returns were lower than Lacombe (CAN $131 ha–1). The Beaverlodge data were from a period of severe drought, resulting in very low crop yields. The Lethbridge site was irrigated, resulting in good yields, but production costs were higher than the other sites because of irrigation. The dry conditions at Beaverlodge could be the reason why there was a significant cultivar effect. Yield was limited by moisture, and the cultivars that lost the least amount of money were generally the ones with lower costs for seed and other inputs (Table 3). The hybrid InVigor2153 had higher production costs and Exceed had lower costs, mostly due to seed costs. All cultivars had yield constrained due to the drought.
The significant interaction of seeding date by PSC for Lacombe and Beaverlodge was because the net returns with PSC were greater for early-fall seeding than for late-fall seeding (Table 4). With late-fall seeding, there was no significant benefit from using a PSC. There was a trend for slightly lower returns for late seeding with the use of a PSC because there was an additional cost without a yield improvement. Late-fall seeding occurred when the soil was considered too cold for seeds to germinate, negating any productivity benefit from a PSC. For early-fall seeding, net returns were higher with the use of a PSC. The benefit of a PSC was CAN $279 ha–1 for Lacombe and CAN $58 ha–1 for Beaverlodge. For these two locations, early-fall seeding of canola without the use of a PSC resulted in some seeds germinating in the fall and the death of these seedlings with the onset of winter. The PSC prevented fall germination when seeding early, and produced a better plant stand and higher yields. At Lacombe and Beaverlodge, late-fall seeding with or without the PSC had net returns at least as high as early-fall seeding. The economic results corroborated the productivity impact of seeding date (Clayton et al., 2004a, 2004b; Karamanos et al., 2002).
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Table 4. Average net returns for fall seeding of canola by location, seeding date, and with or without a polymer seed coat.
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At Lethbridge, the average net returns were not impacted by the use of PSC, hence seeding date by use of a PSC was not reported in Table 4. Net returns for early-fall seeding (CAN $63 ha–1) were significantly lower than for late-fall seeding (CAN $198 ha–1). The net returns from using the PSC (CAN $117 ha–1) were less than from not using the PSC (CAN $144 ha–1). The PSC provided minimal benefit, but was an added production cost. Johnson et al. (2004) reported that in the Rocky Mountain foothills, which included Lethbridge, a PSC provided only a marginal benefit in terms of yield. The effect of seed date in this region was highly variable, likely due to the less-stable fall and winter temperatures. Warm weather in midwinter or very early spring can result in seed dormancy being broken, only to have the weather turn cold and kill the germinated seeds. The PSC did not consistently prevent midwinter or early-spring germination.
The analysis of net returns indicted there would be a limited role for PSC in a fall dormant seeded canola production system. While Willenborg et al. (2004) found some variation in performance of PSC products, with late-fall seeding there would likely be very little benefit from PSC use. One potential role for PSC would be for situations where a producer wants to fall dormant seed canola due to various farm logistics, but needs to seed earlier than just before freeze-up. It might also have more of a role in regions with climatic conditions different from those in this study.
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VALUE OF THE POLYMER SEED COAT
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The economic value of the PSC was measured as the gain (loss) in net returns due to the PSC, expressed per kilogram of seed (Table 5). A value per hectare can be calculated using the seeding rate reported in Table 1. A significant and positive value indicated net returns with the use of the PSC were greater than without the use of the PSC. The value of the PSC varied across location, seeding date, and cultivar. The value was generally positive for early-fall seeding and negative for late-fall seeding. An exception was for early-fall seeding at Lethbridge, where the value of the PSC was not different from zero.
At Lacombe, the value of the PSC was significant for early-fall-seeded cultivars DK 3235 (CAN $65.0 kg–1 seed), InVigor2153 (CAN $32.9 kg–1 seed), and 45A71 (CAN $59.9 kg–1 seed) (Table 5). For late-fall seeding, there was not a significant effect from the PSC for any of the cultivars. At Lethbridge, the PSC generally had a negative value, though only significant for late-fall-seeded Exceed. At Lethbridge, it was not profitable to use the PSC regardless of the time of seeding. Winters at Lethbridge are subject to mild spells where the snow cover melts, soil temperature increases, and premature germination of canola seed, with or without PSC, can occur (Johnson et al., 2004). At Beaverlodge, the value of the PSC was not different from zero for all late-fall seeding. The PSC value was positive for early-fall seeding with cultivars DK 3235 (CAN $14.0 kg–1 seed), Invigor2153 (CAN $6.1 kg–1 seed), and 45A71 (CAN $7.0 kg–1 seed).
The PSC had a positive value for early-fall seeding because it prevented a large yield loss, and the lower net returns associated with a low yield. The PSC did not have a positive value for Exceed because the loss in net returns from not using the PSC was less than for the other three cultivars. Exceed, an open-pollinated cultivar, has been documented to have lower net returns than the hybrid InVigor2153 (Upadhyay et al., 2005). However, for fall dormant seeding, Exceed was not less profitable than the other three cultivars. It also had less loss in net returns for early-fall dormant seeding without the PSC. This cultivar, and others with similar characteristics, could possibly be used for fall dormant seeding because of comparable returns to other cultivars and lower net returns variability.
The benefit to net returns of applying a PSC was less in this study than that determined for corn and soybean in the northern Corn Belt (Archer and Gesch, 2003). However, the benefit was similar to that for PSC treated corn in Iowa and South Dakota (Pecinovsky et al., 2006; Berg et al., 2006). This study used the PSC for fall dormant seeding, while the studies in the northern Corn Belt used it as a risk management tool to avoid yield penalties from late seeding caused by wet weather during seeding. This study did not include a similar yield penalty because the PSC was being evaluated in the context of fall dormant seeding. Another difference among these studies was the Archer and Gesch (2003) study used simulated data, while all others were based on field data. The brand of PSC used in the study could have also impacted the results. Willenborg et al. (2004) found germination of canola seeds depended on the polymer coat treatment. Fall dormant seeding of canola could still have potential in the Canadian prairies (Clayton et al., 2004b; Johnson et al., 2000; Karamanos et al., 2002; Kirkland and Johnson, 2000) despite the low PSC benefits found in this study.
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SUMMARY AND CONCLUSIONS
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The value of using a PSC for fall dormant seeding of canola depended on the time of fall seeding, the cultivar, and the location. The value of using a PSC was greater for early-fall seeding. However, late-fall seeding was more profitable than early-fall seeding at all locations, with or without the use of a PSC. The value of a PSC for late-fall seeding was zero or negative. If a producer needed to dormant fall seed canola, but could not seed late in the fall, a PSC would have a positive benefit and value for most cultivars and locations. If early-fall seeding, a PSC was required to prevent a large loss in yield and low or negative net returns. In the foothills region, where there can be extended warm periods in midwinter that result in seed germination, there was not a positive benefit to using a PSC.
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ACKNOWLEDGMENTS
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The funding for this analysis was provided by the Alberta Crop Industry Development Fund. Comments and suggestions of the reviewers and editors helped to improve the manuscript, though any remaining deficiencies are the responsibility of the authors.
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NOTES
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Lethbridge Research Centre contribution no. 38705061.
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ABSTRACT
INTRODUCTION
