Using winter canola and high-glucosinolate mustards to protect and improve soil resources and enhance on-farm profitability

Using winter canola and high-glucosinolate mustards to protect and improve soil resources and enhance on-farm profitability

Summary

Project staff have successfully completed research station and on-farm winter canola (WC) and high glucosinolate mustard (HGM) trials for the project entitled “Use of Winter Canola and High Glucosinolate Mustards to Protect and Improve Soil Resources and Enhance On-Farm Profitability”.   Weather patterns again affected WC survival. Cold and icy conditions caused a range in survival from complete crop failure at the Aroostook County locations to an average 22% in Stillwater Maine, and 33 % survival at the Vermont location. Areas with better drainage survived considerably better than poorly drained soils. Survival was not as poor as the winter of 2013, where survival was <15% at all locations, but one would not consider the Maine locations in 2014 particularly successful. Winter canola was harvested in Vermont and some varieties produced adequate yields even with substantial winter-kill indicating that low spring populations can compensate for lost plants. A key goal of the WC studies has been to better understand the conditions that lead to overwinter survival, and we have accomplished this. Winter canola will never be recommended for Aroostook County, Maine. With changing weather patterns, we are increasingly finding more icy conditions / partially “open” winters with very cold temperatures. The Orono site had complete failure in 2013, but we found about 20 to 24% survival in 2014. Given the patterns so far, we likely would have had high loss rates again in this current winter. The Vermont location had slightly higher survival rates and maybe a more suitable climate for winter canola production.. So, WC remains a high risk, but possible crop option for Central Maine, while Vermont continues to show somewhat better survival.

Overall, we have found disappointing results with high glucosinolate mustard (HGM) cover crops compared to what we have found with season-long HGM cover crops. While we appeared to have had weather conditions conducive for rhizoctonia activity, it has not materialized as evidenced by black scurf ratings on potatoes or green bean stand counts on the on-farm trials. We have not had large amounts of rhizoctonia at the Stillwater location in either year. The highest amount of black scurf found in any one experimental treatment was 0.5 percent, well below a level or amount that would begin to make a potato unmarketable. Past research has shown that HGM cover crops have been more effective on rhizoctonia than common scab, but if the rhizoctonia activity is very low, it makes it much more difficult to detect changes. Amounts of common scab on potatoes were higher, but also not high enough to question marketability. Interestingly the HGM appeared to have the biggest impact on soil nutrient availability at least at the VT site. We speculate the reasons below.

Objectives/Performance Targets

Forty oilseed growers will adopt WC production and report yield increases of 1000 lbs per acre, and acreage will increase from the current 2000 acres in Vermont and Maine to 5000 acres. By the end of the project yield and acreage increases will generate an additional $750,000 in total farm income in the region.

Twenty-five potato growers that adopt HGMs will report 50% less rhizoctonia, a 20% reduction in culls, and a 25% increase in sales. Potato price per pound varies based on production method and markets, but if yield average is 25000 lbs/ac, and if sold for an approximate price of $0.40/lb, gross returns to the farms on 100 acres of high value potatoes with a 25% increase in sales would be approximately $1,000,000 to the region.

Given the poor WC performance in 2013 and varying results in 2014, few efforts were made to convince growers that WC is preferable to spring planted canola. With and average <35% survival in 2014 in Orono and Alburgh and complete loss in Aroostook County, pitching this as a significantly better planting option is questionable.

One of the potato farmers we worked with in 2012/2013 is growing mustard cover crops on his own this year. He has expressed interest in continuing to do so in future years. If he finds success, we will ask him to work with us in the future to promote its use.

Accomplishments/Milestones

Jemison discussed the impact of late planted HGM cover crops at the Maine Potato Conference – January 23, 2014 in Caribou Maine to 187 people. One article was written for the Oil Seeds and Small Grains newsletter on the benefits of HGM cover crops. I also presented similar information in Prince Edward Island in 2014. I will present our final results at the Potato Conference in January 2015, and to Long Island, NY producers in early January.

In 2014 winter canola was highlighted at the UVM Annual Crop and Soil Field Day. Risks associated with trying this crop were highlighted and it was made clear to farmers that the crop was still being evaluated for its adaptability to our region. There were 225 attendees at the field day.

A field day in Alburgh, Vermont on 1 August 2013 and 2014 attracted a total of 398 attendees. WC and HGM research trials were highlighted, and growers were able to see experiments in the field and ask questions of researchers and fellow producers.

The oilseed producer group, including farmers, extension staff and agricultural sales personnel, will grow from 20 to 40 growers by December 2014 in each state.

Impacts and Contributions/Outcomes

Environmental Conditions for 2013/2014

            The winter conditions were again less than conducive for WC survival again in 2014. While some areas had excellent survival, if ice accumulated, loss was high. Large patches of ice smothered areas of the study leaving a patchwork of canola that survived (see Figure 1a – 1d in Appendix 1). Average survival was 16% in Vermont, 22% in Central Maine and 0 % in Northern Maine.

2014

            The majority of the growing season was warmer than average, but rains led to difficult growing conditions for potato production at the Stillwater, Maine HGM trial and for the on-farm trials in Dixmont, ME. The seed for one variety, Carola, was purchased from a cooperating farmer who was very interested in the HGM results.   This seed was diseased with black leg and emergence was very poor (<5%). While the rainfall led to average yields, it also led to a lack of stress that again did not provide conditions conducive for potato skin surface diseases. As a result, different cover crops did not greatly influence potato skin disease for a second year.

Winter Canola Trials – 2013 and 2014

Variety by Potassium Trials – Stillwater Maine 2014

            As mentioned, there was poor survival in all WC trials conducted in 2012. We did find some varietal differences in the survival rates found among varieties in the variety x potassium rate study in Maine. The top four survivors were Kiowa, Dynasty, Wichita and Riley. The same eight varieties were planted again in a trial at the Rogers Farm in Stillwater, Maine on August 22, 2013. A week following, the best surviving four varieties from 2012 were replanted with and without K to see if a later planting date would be beneficial or detrimental.

            Plant stands were assessed in October to establish production potential. Data are presented in Figure 1 and Figure 2 uploaded below.  

In 2014, Dynastie and Hornet had the highest survival followed by Riley and Wichita (see Table 1 uploaded below). These four varieties are likely the ones worth pursuing further. Not unsurprisingly, yields were highly correlated to survival. In Figure 2, yields of the eight WC varieties are presented from Stillwater, 2014.   Dynastie, Hornet and Riley yielded the highest and also had the best survival (see Figure 2 uploaded below).

Potassium additions were not found to significantly affect yield or survival. While winter survival affected yield, potassium did not significantly add to winter survival.

 
Planting Date X Seeding Rate Trial – Maine Results

In 2012, the overall average WC survival was less than 7%, but the best survival was found with the August 21^st planting date and at the 5 lb ac^-1 seeding rate (See Figure 3 Uploaded below).

Based on these findings, we shifted the planting dates for 2013 by a week. Planting dates in 2013 were done on eight-day intervals beginning on 8/12, and ended on 9/5, and we used the variety Riley for all of this work. Survival of the WC planted over the four dates is presented in Figure 4 uploaded below.

Stand counts were taken on 22 May 2014. Neither planting date nor seeding rate significantly influenced survival, but yield of WC planted later increased yield relative to the earlier dates (Figure 5 uploaded below).

 Soil Management Trial – Maine Results

The final trial we conducted was a soil management/planting trial to assess the benefit of rolling a field prior to drilling, rolling a field after drilling or simply drilling in the seed. As can be seen in Figure 6 (uploaded below), rolling the field both prior to and following drilling seed significantly improved winter survival. While one might think the extra management might reduce infiltration, our results suggest that possibly frost heaving is reduced with a more compacted soil.

We took yields on this trial and in contrast to the variety trial, in this case higher survival did not lead to higher yield (Figure 7 – uploaded below). Despite the lack of yield differences, packing a field after harvest is a good management practice given the size of the seed.

Summary – Maine

Winter canola yields are about 30% higher than our area average spring canola yields. While yield improvements are good, the variation in yield across the fields was great to due large patches of dead canola. The weed issues caused by winter cress growing without WC competition in these areas were also problematic. Based on the data collected in these trials, we would not want to promote WC in Maine due to the questionable survival. But, if a grower were to want to try, these are the protocols we have developed to follow to enhance the potential for success.  

• Select fields that are likely to have improved drainage, where water will not pool and freeze.
• Select the most winter hardy variety you can find: Riley, Dynastie and Hornet were the best varieties for Maine.
• When planting, have a smooth prepared seedbed and roll the field after drilling as a minimum to ensure good seed to soil contact.
• Plant between the third week in August and the first of September for Central Maine. This appears to provide a sufficient length of time to ensure good rooting but not so much time as to develop too much leaf area that might hurt winter survival.
• Plant at a 4 to 5 lb seeding rate. We did not find any advantage to a higher seeding rate.
• Ensure that your potassium levels in the soil are moderate to high, but there does not seem to be any benefit to higher added rates of potassium.

Vermont Results –

Variety Trial

The 2014 variety trials proved to be more successful than the complete crop failure experienced in 2013. It was apparent that variety selection would be critical to this crops’ success in our region. The winter survival of varieties ranged from 4.00 to 36.0 percent (Table 2). The variety with the best winter survival also had the highest yields. Interestingly it appears as though a significant amount of canola plant loss can occur and the remaining plants can partially compensate for the lower plant populations. Hence slightly higher seeding rates may be warranted.

Table 2. Yields and winter survival of winter canola varieties in Alburgh, VT.

Seeding Rate x Planting Date Study

In 2013, though there were no statistical differences in fall plant height , spring population, or overall winter survival across seeding rates, fall populations did vary by seeding rate (Table 2). Higher seeding rates led to denser fall populations, though this was not necessarily advantageous for the stand’s winter survival. The same seeding rates were used again in WC planted in Vermont’s Seeding Rate x Planting Date study.

Table 3. Effect of seeding rate on fall establishment and winter survival in WC, 2012/2013, Alburgh, VT.

Planting dates had a significant impact on the winter survival of canola, with the greatest survival rates in canola planted late August (Figure 8 – uploaded below). In 2013, winter canola was planted in weekly increments ranging from 16-Aug to 6-Sep.

In 2014, a trial to evaluate the impact of planting date and variety on winter canola survival and yield was initiated at Borderview Farm. There were 3 varieties planted that have shown good potential for the region on 4 different planting dates. Winter survival and yields were recorded. There were no significant differences between planting date or variety observed for winter survival or yield (Table 4). Indicating that canola would perform well planted between mid August and very early September.

Table 4. Effect of variety and planting date on winter survival                                                                                 and yield in WC, 2013/2014, Alburgh, VT.

NS- not significant at the .10 level

Management Trial

Vermont Results –

In the Vermont 2012/2013 trial, there were no significant differences in fall establishment or winter survival by seedbed preparation method (Table 5).

Table 5. Effect of soil preparation treatment on WC establishment and survival, 2012/2013, Alburgh, VT.

NS- not significant at the .10 level

Similar in the Vermont 2013/2014 trial there were no significant differences in winter survival or yield by seedbed preparation method (Table 6 and 7).

Table 6. Growth characteristics by soil preparation method, 2013-2014

NS- not significant at the .10 level

Harvest characteristics did not statistically differ between soil preparation methods (Table 7). The lowest harvest moisture was 12.4% in the pack + drill + pack method. The highest test weight and oil yields and lowest pressing moisture of 49.8 lbs. per bushel, 288 lbs. oil per acre, 38 gal. oil per acre, and 6.5% respectively, were observed in the pack + drill method (Figure 2). The highest seed yield reported at 8% moisture was 813 lbs. per acre in the drill+ pack method.

Table 7. Harvest characteristics by soil preparation method, 2013-2014

NS- not significant at the .10 level

2014: High Glucosinolate Mustard Biomass Production by Planting Date

            We continued to study the effect of high glucosinolate mustard incorporation on potato yield and skin surface quality in 2014 in research station trials in Stillwater, ME, in on-farm trials on potatoes and green beans in Dixmont, ME and on green beans in Alburgh, VT.

Research Station Trial – Stillwater Maine

            In 2013, we planted HGM trial on 11-day intervals starting on August 6 and ending on August 26. A significant HGM by planting date interaction was found in 2013 (Figure 9 uploaded below). This was caused in part by the very wet August conditions that caused the oats to be diseased and yield poorly, particularly in the first planting. The HGM in both of the first two plantings yielded well, averaging about three tons of dry matter per acre.

On-Farm Trials – Maine

Mustards were planted at the Guzzi farm on August 14^th, however no rain fell for about a 10-day period and germination did not fully occur until the end of the month. We produced only an average of two and a half tons of dry matter, but again, the mustards produced significantly more biomass than the oats (Figure 10 – uploaded below).

The cover crop yields from the second on-farm (bean) trial were considerably lower (Figure 11-uploaded below). The oat yields between the two trials were similar, but the yield of the high glucosinolate mustards were considerably higher in the first trial. Soil conditions in the second trial were wetter when the soil was worked and that may have led to poorer emergence and thus lower biomass yields.  In each trial, following biomass sampling, cover crops were flail mowed, and incorporated within an hour of mowing. We tried to incorporate just prior to a rain event.

2014: Maine Results – Potato Harvest – Experiment station results.

Marketable and Total Yields.

            Potato yields from the 2014 season were considerably lower than for 2013. The Carola variety had to be dropped from the study in 2014 due to poor germination and emergence (<5% survival). Marketable yield in 2014 was not influenced by the type of cover crop present, but was influenced by planting date. While one would logically think that more incorporated biomass would lead to higher yields, this was not the case in 2014 (Figure 12 – uploaded below).   A possible explanation for the unusual planting date findings is that with the excessive precipitation found in 2014, the incorporated biomass might have led to wetter soils and poorer production? Although this was considerably different from the results found in 2013. Where we simply applied mustard meals in the fall and the spring, we found greater potato yields compared to the potatoes grown following biomass incorporation, which could support the excessive water hypothesis (Figure 13 – uploaded below).

Unfortunately, this is the opposite result of what we found the previous year (Figure 14 – uploaded below).

Potato Skin Quality – Common Scab

            Some common scab (Streptomyces scabiei, T.) was found on the Yukon Gold potatoes in 2014, but not at levels high enough to make a significant difference or marketable difference (Figure 15 – uploaded below). Given the high variability (as seen be the high error bars around the means) levels appeared to be more affected by position in the field than due to cover crop treatments. When common scab infections exceed about 5% of the surface area, potato marketability will suffer. In this case, most of our levels were below 2%, indicating very low infection levels. Ground HGM meals added to the soil provided no more or less effective in controlling common scab as levels were generally at or around 1% surface area as well.

Potato Skin Quality – Black scurf

            Black scurf, caused by Rhizoctonia solani, was less apparent in 2014 than common scab. HGM mustards have been shown to suppress the activity of rhizoctonia, but in 2014 as in 2013, we were unable to statistically show that black scurf in the potatoes following oats was significantly higher than potatoes planted after incorporation of other HGM treatments. While potatoes grown following oats were higher in both common scab and black scurf, the amount of variability masked any possible difference (Figure 16 – uploaded below). The black scurf levels found with Yukon Gold never approached levels of economic significance. The wide error bars also suggest that position in the field may have had some influence on scab levels. Meals added to the soil were similar to the IGM and other cover crops. They were no more or no less effective in controlling rhizoctonia.
 

Potato Skin Disease Summary

            Overall, skin surface disease was low again in 2014 as it was in the previous year (Table 8). Lack of dry conditions at tuber initiation and a lack of a prolonged cool wet spring led to low amounts of skin surface disease. When conditions are not conducive for skin surface diseases, slight differences in field drainage and small microclimates can often play a bigger role on potato skin surface disease than the treatments we are trying to compare.   As such, I believe this partly explains our results. The other issue is timing. We generally mow and incorporate these plants when the soil is considerably cooler than what we did in previous experiments. It is logical that soil reaction time is slower due to the cool conditions and that may influence fate and efficiency of the glucosinolates to control soil borne pathogens. In contact with researchers in Idaho, I have learned that they have had also had less success with late processed mustards compared to mowing in August.

Table 8. All data from the On-Station Trial – Stillwater, ME

On-farm Studies, Maine

            In the summer of 2014, we planted potatoes following the late fall 2013 incorporation of HGM in one on-farm location, and we planted beans following cover crop incorporation in another experiment. The first trial was conducted in Dixmont, ME where potatoes were planted in the spring following fall destruction of three cover crops: mustard variety 119 (in one experiment), oriental mustard or oats and mustard variety 199, oriental mustard and oats in the green bean study.

            We intended to take yields and assess potato skin quality with two varieties planted across all the cover crops. We supplied the farmer with seed, and like what happened in Orono, one variety (in this case Yukon Gold) had very poor germination and emergence. The other one was mistakenly harvested for sale. We did not try to harvest the Yukon Gold for yield due to the poor, variable stand density, but we sampled potatoes from each plot so that we could assess skin surface quality for cover crop differences. In 2014, the HGM cover crop did not lead to significantly higher quality skins on the potatoes. This past summer was very wet, and there was little stress at tuber initiation to lead to significant levels of common scab. In the potato trial, black scurf level on potato skins was not different from the oat cover crop (control) Table 9.

Table 9. Potato skin quality assessments from on-farm trials, Dixmont, ME

2013 and 2014

            Rhizoctonia can reduce legume germination. In the second on-farm trial, we tried to assess if HGM could reduce Rhizoctonia activity evidenced by higher bean population following mustards compared to oats. Stand counts were taken in the first trifoliate stage of development (Table 10.) No differences were found in the second study consistent with what we found in the potato trial. With lower cover crop biomass in the green bean study, it follows that this trial had less potential to see a difference.

Table 10. Green bean and lettuce stand count assessments from on-farm trials, Dixmont, ME – 2014

Summary

            We have not seen the reduction in potato skin surface disease expression that we found in previous studies. In conversations with researchers in Idaho doing similar planting dates and cover crop destruction protocols, they have found less effect as well. There are a couple of possible explanations. While biomass amounts are similar to amounts produced in full season plantings, it is possible that the amount of glucosinolates generated by the plant or glucosinolate activity is generally lower when the weather and soil is cooler at the time of destruction and incorporation.   In almost every instance, the control plot had higher levels of scab and black scurf, but the differences are less than what we found in the previous work. It is unfortunate as growers can get a harvestable crop off the field and leave the field covered through the fall. An October cover crop incorporation seemed to be a much better fit for farmers, but from the data we have collected, it has not as effective.

2013: Vermont Results – Potato Harvest – Experiment station results.

An on-farm trial in Center Rutland, Vermont in 2012/2013 evaluated HGM cover crops on the yield and quality of a following potato crop. Two HGM varietal mixes were planted in late summer of 2012, then plowed under and incorporated in November 2012 (Table 11).

Table 11. HGM crops harvested in fall 2012, Center Rutland, Vermont.

There were no significant differences in yields of either red or gold potatoes based on HGM cover crop treatments (Figure 17 – uploaded below). There was likewise no significant impact of HGM cover crops on potato population, weed populations or skin disease.

2013: Vermont Results – Black Bean Harvest – Experiment station results.

In 2012/2013, a study in Alburgh, Vermont evaluated whole plant HGM cover crops, fall-applied HGM meal, and spring-applied HGM meal as a strategy for reducing weeds and improving yields and quality of black beans. There were no significant impacts on nitrate levels, bean populations, weed pressure, or yields of black beans based on HGM treatment. The study wasrepeated in 2013/2014.

2013/2014 Research Station Trials – Vermont

In 2013/2014, a study in Alburgh, Vermont evaluated whole plant HGM cover crops, fall-applied HGM meal, and spring-applied HGM meal as a strategy for reducing weeds and improving yields and quality of black beans. There were no significant impacts on nitrate levels, bean populations, or yields of black beans based on HGM treatment (Table 12).

Table 12. Yield of HGM crops and Black Beans treated with HGM amendments 2013/2014, Alburgh, VT.

• Figure 3. planting date and seeding rate trial survival
• Figure 6. Effect of Soil Management on Winter Survival – Stillwater ME 2014
• Figure 12. Marketable yield of Yukon Gold potatoes – Stillwater, Maine 2014
• Figure 14. Comparison of meal vs. cover crop influence on marketable potato yield, 2013, Stillwater, Maine.
• Figure 1. Plant stands by Winter Canola Variety
• Figure 13. Marketable yield of Yukon Gold potatoes – Stillwater Maine – 2014
• Figure 2. Yield of eight winter canola varieties – 2014 – ME
• Figure 4. Effect of planting date and seeding rate on stand survival at the Rogers Farm, Stillwater, ME.
• Figure 5. Winter Canola Yield based on planting date – Stillwater ME 2014
• Figure 7. Yield of winter canola following different levels of soil management
• Figure 9. Yield of late season planted cover crops – 2013, Stillwater, Maine.
• Figure 15. Effect of cover crop on potato skin surface area of common scab, 2014, Stillwater, ME.
• Figure 16. Effect of cover crop on potato skin surface area of black scurf, 2014, Stillwater Maine .
• Figure 17. Effects of HGM cover crop treatments on potato yields, 2013, Center Rutland, Vermont.
• Table 1. Winter Canola Variety Survival – Stillwater ME. 2014
• Figure 8. WC winter survival by planting date, 2012/2013, Alburgh, VT.
• Figure 10. Yield of late season planted cover crops – Dixmont, Maine.
• Figure 11. Yield of late season planted cover crops – Green bean trial – Dixmont, Maine.

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