A Closer Look at Flax

Guy Lafond ¹, Cindy Grant ², Doug Derksen ², Adrian Johnston^3,

David McAndrew ^4, Geza Racz⁵ and David Wall ⁶

1 Indian Head Research Farm, P.O. Box 760, Indian Head, SK, SOG 2KO

² Brandon Research Center, P.O. Box 1000A, R.R.#3, Brandon, MB, R7A 5Y3

³ Melfort Research Farm, Box 1240, Melfort, SK, SOE 1AO

⁴ Morden Research Centre, Unit 100-101, Route 100, Morden, MB, R6M 1Y5

⁵ Dept. of Soil Science, University of Manitoba, R3T2N2

⁶ Saskatoon Research Centre, 107 Science Cres, Saskatoon, SK, S7N OX2

A. Introduction

One of the five pillars of direct seeding is crop rotation. By maintaining a diversified crop rotation, problems associated with weeds, plant diseases, and crop residues can be managed profitably. Flax is a broadleaf crop that can easily be worked into a rotation. It has been shown to respond very well to direct seeding for reasons that will be discussed in this paper. It is a crop that is easy to establish and seed costs are low relative to other crops, especially other oilseed crops. In terms of weed control, the choice of herbicides, especially for grasses, is very good to excellent. The choice for broadleaf herbicide is more restricted but those that are available are very effective. As a rule, plant diseases are usually not a problem. Genetic resistance is included in all varieties being licensed to the more important diseases like wilt and rust. In terms of insect pests, no specific one can be tied to flax as such. However, general attention has to be given to pests like grasshoppers, bertha army worms, pale western and red backed cutworms. From a harvest management point of view, this is a crop that lends itself very well to straight combining because of its standability and good shattering resistance, especially when linked with pre-harvest Round-Up for weed control and crop dessication.. We also need to talk about some of the disadvantages with this crop. One frequently cited disadvantage is the difficulty in managing the crop residues remaining. Unless the residues are physically removed from the field, they usually have to be burned because of the difficulties created during the seeding operation. Another potential problem is its poor competitive ability against weeds. Yield losses can be very high in situations of heavy weed pressures or poor weed control.

The objectives of this paper are to highlight flax production in the context of direct seeding by focusing on crop water use, recropping and tillages systems. Information about the interaction between environment and broadleaf herbicides will also be presented with some information on the appropriate timing of herbicide application. Attention will be focused as well on the response of flax to the major nutrients with emphasis on fertilizer form and placement. For more information on other aspects of flax production, the readers are advised to visit the Flax Council of Canada WebSite on the Internet at: http://www.flaxcouncil.ca

B. Direct Seeding and the Implication for Soil Water Management and Crop Water Use in Flax

A number of questions need to be addresses with regards to water management and flax production.

1. What is the extent and depth of soil water extraction by flax?

2. Does tillage system affect the extent and depth of water extraction?

3. How does recropping to wheat affected by flax and relative to other oilseed crops? 4. How is crop water use reflected in grain yield and how does it relate to soil water?

What is the extent and depth of soil water extraction by flax?

Detailed soil water measurements on a heavy clay soil over three growing seasons has shown that flax is not a deep rooting crop. In fact, flax obtains 90% of its soil water in the 0-24" soil layer (Table 1). No change in soil water between the seedling stage and crop maturity was detected in the 36" to 48" soil layer with very small changes in the 30-36" soil layer. Given this information, how does it compare to spring wheat. Since spring wheat was also being measured in those studies, we observed that although similar amounts of total water was being extracted from the soil in the 0-48" soil profile, spring wheat extracted moisture deeper in the soil profile than flax but not to the same extent in the 0-24" soil layer meaning that flax is capable of extracting more water out of a given volume of soil than spring wheat. This increased extraction is to be expected from a crop which tends to have a longer growing season than wheat. This would explain why producers have observed that soils are harder after a flax crop. According to these results, it is a reflection of simply a drier soil thereby giving it more strength.

Does tillage system affect the extent and depth of water extraction?

The study from which these results are drawn from also had a tillage component thereby allowing us to make the comparison. Given the results in Table 2, it is obvious that the pattern and extent of water extraction is not affected by tillage systems.

How does recropping to wheat affected by flax and relative to other oilseed crops?

A study which was run in 1995 and 1996 examined the relative performance of canola, flax and sunflowers and their subsequent effect on wheat. The results show that over the three site years, the spring wheat yields were very similar among the three oilseed stubbles (Table 3). Research in Manitoba, based on production records obtained from the Crop Insurance Company for the years 1982 to 1993, showed that wheat following flax, pea and canola was, on average, 16%, 11, and 8% higher than wheat after wheat (Bourgeois and Entz, 1996. C.J. Plant Sci. 76:457-459). This emphasizes the importance of flax in a crop rotation.

How is crop water use reflected in grain yield and how does it relate to soil water?

A detailed description of this information is given in Table 4. In a nutshell, the difference in spring soil water between direct seeding and conventional tillage is similar to the difference in soil water use during the growing season and the difference in total crop water use is very similar to the difference in soil water conserved between direct seeding and conventional tillage. Grain yields averaged 13% higher for direct seeding than conventional tillage over the 1987-1996 period.

Based on the results presented, it can be concluded that enhancing yield through direct seeding is only possible if extra moisture can be stored. Consequently, the strategy is to develop water management practises that can enhance water conservation because of its direct positive impact on crop water use and grain yield. One should also not overlook the fact that direct seeding provides a better environment for crop establishment as well.

C. Plant Diseases

When the problems of plant diseases in flax are compared to other oilseed, pulse and cereal crops, they tend to be insignificant. However, it is important to recognize and acknowledge some important diseases in flax.

The most important disease is wilt caused by Fusarium oxysporium. This is a soil-borne fungus that invades the plants through the root system. Infection may occur in cool soil but as a rule, the disease usually develops best in warm weather. The most important and effective control measure is to use resistant varieties and fortunately the varieties registered in Western Canada have very acceptable resistance. However, it is important to maintain a healthy crop rotation to minimize the chances of establishing the fungus into a new field.

The other disease to pay close attention to is pasmo caused by Septoria linicola. This disease is more prevalent in the eastern Prairies i.e. eastern boundary of Saskatchewan and across the flax growing areas of Manitoba. This fungus attacks all above ground parts of flax and causes pre-mature ripening resulting in a reduction in grain yield and quality. The best control measure is to avoid seeding infected seeds, sow the flax crop early and leave at least 2-3 years between flax crops.

For more information on these plant diseases, consult the publication Diseases of Field Crops in Canada: An illustrated compendium, by J.W. Martens, W.L. Seaman, T.G. Atkinson.

D. Chemical Weed Control

Several post emergence herbicides are registered in western Canada to control broadleaf weeds in flax, including Basagran, Buctril M, Hoe-grass II, Lontrel, MCPA/MCPA K, and Stampede CM. Buctril M is the most widely used of these herbicides. This is likely due to a combination of factors, including cost, crop safety, and weed spectrums controlled. Bromoxynil, an active ingredient in both Buctril M and Hoe-grass II, controls many annual broadleaf weeds such as tartary buckwheat that do not respond to phenoxy herbicides. Other weeds controlled by this herbicide include kochia, lamb=s quarters, smartweeds, stinkweed, wild mustard and wild buckwheat. Buctril M is a formulated mixture of bromoxynil octanoate ester and MCPA ester. The addition of MCPA ester not only improves the control of weeds already controlled by bromoxynil, but also provides activity on flixweed, shepherd=s purse, perennial sow thistle, Canada thistle, and volunteer canola and sunflower.

Flax producers often report injury (stem twisting, stunting and leaf burn) to flax following application of Buctril M. To reduce the chance of injury, Buctril M should not be applied to flax if daytime temperatures exceed 27 C within 48 hrs before or after application, and evening spraying may also reduce the risk of injury. Anecdotal reports suggest, however, that crop injury can occur even when these recommendations are followed. We do not know if whether the crop injury reported by producers has actually reduced crop yields. Buctril M is a useful herbicide for broadleaf weed control in flax and producer confidence in and continued use of this product is desirable from a user perspective.

Buctril M has been registered for use in flax since early to mid-1970's, and many studies have been published in the Research Reports of the Expert Committee on Weeds (ECW) on its efficacy and selectivity in flax. A review of studies published in the ECW Research Reports was done to identify application factors that may improve crop safety to Buctril M.

E. Fertilizer Management

The nutrient content of flax seed is high relative to cereal and very similar to canola and field pea (Table 5). This means that high flax yields is commensurate with the need for a high level of available nutrients, whether they come from the soil or inorganic fertilizer. Relative to wheat, flax seed has 40% more nitrogen, 44% more phosphorus, 200% more potassium and 59% more sulfur on a weight per weight basis.

Given the high level of nutrients in flax seed, what is the response of flax to nitrogen relative to canola. In Table 6, the results show that flax and canola respond very similarly to nitrogen (available soil N and fertilizer N). If the response to N is similar between flax and canola, are the fertilizer recommendations for nitrogen similar? A summary of fertilizer N recommendations for different soil nitrogen levels and different yield targets is given for flax and canola in Table 7. For target yields ranging from 25 - 30 bus/acre, the recommendations were always lower for flax than canola, regardless of the soil nitrate-N levels, in this case ranging from 10-60 lbs/acre. In general, based on the above results, it could be concluded that at lower yield levels, the nitrogen recommended for flax should be increased.

With regards to fertilizer management, a number of important questions have been addressed with some recent research studies. Questions pertaining to nitrogen fertilizer form, nitrogen placement, time of nitrogen application and placement of phosphorus fertilizer (mono-ammonium phosphate in this case). In the Saskatchewan context, fertilizer management in flax has to be compatible with a one-pass seeding and fertilizing direct seeding system.

Is nitrogen fertilizer form important to enhance the response to phosphorus fertilizer?

It has been reported that using ammonium sulfate as a nitrogen source can enhance the response to phosphorus when placed in a dual band on grain yield. The other important aspect is what effect these fertilizer forms have on plant establishment when all the nutrients are side-banded.

In the case of plant populations, it would appear that urea causes a greater reduction in plant numbers than ammonium nitrate or ammonium sulfate, even when it is placed away from the seed. This supports the observation that flax is very sensitive to fertilizer (Table 8). Although plant populations are more than adequate to maximizing grain yield, there may still be some sub-lethal injury which in turn may have impact negatively on the ability of the crop to compete successfully with weeds.

With respect to grain yield, for the most part, fertilizer form did not have any important effects or performed equally. It should be noted however that in one instance, Brandon >97, the yield with ammonium sulfate was distinctly better.

Does the placement and form of fertilizer affect grain yield and plant populations?

With these studies, we were able to compare ammonium sulfate to urea when side-banded or else applied prior to seeding as a preplant band with the phosphorus fertilizer always placed in a side band situation. Plant populations were lower for urea than ammonium sulfate and when the urea was pre-plant banded, the populations were similar to the ones with ammonium sulfate (Table 9). Again these results emphasize the sensitivity of flax to fertilizer damage, especially with urea.

In terms of grain yield (Table 9), grain yields tended to be higher when the nitrogen was side-banded rather than pre-plant banded and were similar between urea and ammonium sulfate except at one location, Brandon >97, the yields were higher for ammonium sulfate than urea, regardless of the placement. The results emphasize the yield benefits that can be realized in a one-pass seeding and fertilizing system.

How does the timing of fertilizer nitrogen application influence the placement of phosphorus fertilizer?

Although the overall response to phosphorus was not large for all locations (Table 10), there was some yield improvements to be observed through careful placement of the nitrogen and phosphorus fertilizer. However, when averaged over all sites, the differences were not large. These effects could also be masked somehow because of the overall low response to phosphorus. The results did point to the fact that using a one-pass seeding and fertilizing system is an efficient way to proceed for flax production.

What is the overall response to nitrogen and phosphorus in a dual band situation using a one pass seeding and fertilizing system?

Six site years of information were collected dealing with nitrogen and phosphorus responses (Table 11). There was a significant response to nitrogen at all locations and a response to phosphorus in half of the locations. The results emphasize the need to provide adequate levels of nitrogen.

F. Conclusions

Flax production is very compatible to direct seeding and the potential to improve on yield is tied almost directly to the ability to harvest more water, whether it be in the form of snow or more efficient use of growing season precipitation. This potential is tied to direct seeding because it makes all of this possible. Better use of water is also tied to adequate nutrients for crop growth. Poor use of water is possible with improper fertilizer use. The results emphasize the requirement for proper nitrogen fertility and that some improvements in the efficiency of phosphorus is associated with its placement with nitrogen. The results have also shown that the greatest opportunity for increased flax yields is using a one-pass seeding and fertilizing system as part of a direct seeding system.

Acknowledgement

The research results presented in this paper were made possible through funding from Agriculture and Agri-Food Canada, Agriculture and Agri-Food Canada=s Matching Investment Initiative, Parkland Agricultural Research Initiative, Saskatchewan Agriculture Development Fund, Flax Council of Canada, Agrium and the Potash and Phosphate Institute.

Table 3. The effect of oilseed stubble on the yield of spring wheat (bus/ac).

Table 6. The response of canola and flax to nitrogen (soil and fertilizer).

Table 8. The effects of nitrogen fertilizer form on plant populations and grain yield in flax.

Table 9. The effects of nitrogen fertilizer form and placement on plant populations and grain yield in flax.

Table 10. The effects of timing of application of nitrogen and phosphorus fertilizer placement on grain yield in flax.