Alaska vegetable production using a high residue cover crop system to reduce erosion and decrease weeds

2021 Annual Report

In the year of establishment (2020) an early and late planting of 10 cover crop mixes were established.  The early planting was terminated before any species produced viable seed using a hand crimping method: a 24" segment of 4" aluminum c-channel.  The late season planting was terminated by a killing frost well before any species began flowering.  As of April 2021, all treatments have residue laying on the ground and are covered by 18" of snow.  They await measurement of ground cover (beaded string method) and determination of  overwintering biomass (dry wt/sq ft).

One of our participating farmers was not able to allocate the irrigated space early enough for us to plant the cover crops.      His operation will contribute the transplants for all sites and we will use imported residue to simulate the residue treatment for his 2021 growing season.

The equipment side of the project is completely off schedule and has forced us to change field protocols to keep the biological aspects on schedule.

Roller Crimper:   The fabrication shop in our area has been overwhelmed with work and was not able to complete our roller crimper in time for the project.      As a temporary solution we used a 2' piece of Aluminum 'C-channel' with a set of strings as a make shift crimper.  Several YouTube videos feature cover crop crimping by hand and we essentially followed their examples.  So, rather than crimping all the plots in an hour with a mechanized roller-crimper, it took the district's intern most of a day at each location to crimp the plots.

No-till Planter heads:   I have only found one vender that will sell individual no-till heads and they are not used to shipping to Alaska.  I've tried getting them to air freight the pallet, which surprisingly is the least expensive option, but they are not a Homeland Security Preferred Shipper so that method turned out to be a dead end.  I've also found a trucking company that routinely goes between Montana and Alaska  but the vender's usual trucking company is not set up to drop the pallet off to another shipping company.  The project budget has funds for the purchase of the no-till heads but I'm struggling with how to get them here.      Recently, the local trucking company that used to only go between Montana and Alaska is trying to expand their operations and would be willing to coordinate shipping directly from the Esch facility to Alaska.  The no-till heads won't get here in time for the early cover crop planting so we'll put the treatments using conventional tillage methods.  I'm also leaning on the no-till company to be a bit more responsive and sell me the needed no till heads

2022 Annual Report

In Spring of 2021 there were no treatments that had overwintering residue heavy enough to give any level of weed mulching effect.  This observation was met at both the Sun Circle site and the Rebarchek Incubator Farm site.  The only weed smothering effects were seen associated with the oat treatment and the heavy oat planting put in around the plots to serve as a walkway.   The mulching effect of the former walkways was incredible, while all the plots were growing weeds through the residue the former walkways were almost weed free.  A consultation with the WSARE team allowed us to modify the original proposed treatments to use the heavy reside from the walkways to serve as a weed mulch in the treatment.  The straw residue was removed from 1/3 of the area and dumped on top of the existing residue in another 1/3 of the area giving three rates of oat straw residue: none, 1X and 2X.

Although some level of weed mulching effect was seen in the 1X and 2X treatment areas the grower asked us to terminate the trial mid-season.  She notices a significate increase in slug damage associated with the mulch.  As an organic grower with limited options for slug management, removing the reside that provided protective cover seemed to be the best option.

On the Rebarchek Incubator Farm location there was no level of weed suppression associated with the cover crops and not as much oat straw was planted for walk ways so there was no option to use reside to hinder weed growth.  Rather, on this site oats were planted in mid-August and the last week in August at 4 rates to determine if increasing the seeding rate would compensate for later planting times (essentially, can money buy time).  The first two planting dates went fine with the heavy planting rates giving almost a full coverage of all surface area of the plots.  Unfortunately, due to an unanticipated state-wide shortage of oats the September plantings could not be seeded.

The five no-till planter heads located in the Spring of 2020 were finally delivered to Alaska in September of 2021- 16 months after identifying a source in Pennsylvania.  As of May 13th 2022 the heads are still covered with 2' of snow.  I have been working with a local fabricator to re-design the planned no-till planter after he determined that my original design would not work with the planned tractor.  A no-cost extension was applied for to allow the project to fabricate the planter and shoot videos of it putting in various cover crops.

Three Powerpoint presentations have been given on the status of Alaska Cover Crop projects and this SARE project has been prominently featured.   In the Winter of 2022 a (Zoom) presentation was made to the Western States Cover Crop Group.  In November 2021 the presentation was given at the Alaska state-wide SARE conference in Anchorage and in February 2022 the presentation was given (via Zoom) as part of the Kenai Peninsula Ag Workshop Series.

Final Report (October 2022)

Using Cover crops for weed suppression in Alaska vegetable production

Cover cropping is a concept that is not well adapted in Alaska.  Our very short production seasons (Mid-May through Mid-September) along the goal of keeping our very expensive land in production as much as possible strengthens the mis-conceptions that cover crops are not a good strategy for Alaska.  When surveyed for what their goals of cover cropping would be the three most frequent responses are suppress weeds, minimize erosion and increase fertility.

This project had two separate components that should ultimately work together.

Component 1:  Developing a small-scale no-till planter appropriate for Alaska’s vegetable producers. 

Alaska’s vegetable operations are very small compared to those in the Lower-48.  All but two of our growers would be considered market farmers producers in other states.  Most of Alaska growers measure their production in row-feet rather than acres.  Our growers also don’t have access to much of the specialized vegetable production equipment common in areas with farm implement dealers.  Consequently, to roto-tiller is used for soil preparation, weed control and residue burial for disease management.  In additions to the soil health impacts, using a roto-tiller to prepare the area for cover crop seeding has the undesired effect of bringing up all the weed seeds which compete with the cover crop.  Our technical professional has strongly advocated for seeing the cover crop using a no-till planter to get the seed to depth with a minimal disturbance of the surface, essentially creating a stale seedbed condition.  Unfortunately, we only know of three no-till planters in the entire state.  A very large no-till drill, a very small planter meant for establishing food plots for hunters using an ATV and a 7’ drill owned by the State’s Plant Material Center.  While the state’s 7’ no-till drill would be capable of planting through standing vegetable residue it doesn’t lend itself to going from farm to farm for small projects.  Consequently, one of the aspects of this SARE project was to create a small no-till drill that would be 1) able to cut through standing residue, 2) very maneuverable on small farms and 3) readily transportable over public roads.

There are no ‘Farm Equipment Graveyards’ in Alaska so repurposing the planter heads from a junked no-till planter was not an option.  Calling numerous graveyards in the lower-48 was also not successful once the operators found that we wanted them shipped to Alaska.  We finally located a dealer in Pennsylvannia that was willing to sell us 5 no-till heads but could not figure out shipping to Alaska.  Between covid disruptions and ‘very creative shipping strategies’ the five new no-till heads showed up in Alaska 18 months after the SARE funding was allocated.  A week after arrival winter set in and the pallet of no-till heads was frozen in a deep snow drift until the May thaw.  Once the pallet was freed from the snowbank the fabricator was to busy to work on the planted during the cropping season and the fabrication is scheduled for the winter season of 2023.

An unexpected benefit of this delay has been a complete re-design of the planter.  Initially we planned to mount the planter heads on the underbelly section of an Oggun cultivator tractor.  This design would combine the trailerability and maneuverability of the Oggun tractor with the appropriate weight to cut through the residue.  Unfortunately, while cultivating the field for the other component of the trial a cultivator didn’t trip when hitting a rock and the tractor’s axle broke instead.  With this indication we decided that the 1,800 lb tractor may be too small for the planter heads.  We redesigned the planter to be a pull-behind planter instead.  Rather than using the tractor’s weight for down pressure the redesigned planter uses a 50 gal water tank as removeable ballast.  To provide the seed for the planting heads, a Gandy ‘Research model’ 1 cu ft Air seeder will be mounted on the trailer above the planter heads.  The planter heads are mounted on 4” tubing at 15” intervals asymetric from the planter’s wheel tracks.  This is to facilitate higher density planting.  On an East to West pass 5 rows are put in at 15” spacing.  Doubling back over the same tire tracks a West to East pass puts in another 5 rows skewed to the right, effectively giving a 5.5’ (double) pass with 10 rows spaced 7.5” apart.   By making two passes we can get by with half the number of planter heads and still keep the overall implement weight in a reasonable range for transport.  While this strategy would be impractical on large fields given that most of Alaska’s vegetable growers would be looking to put in cover crops on less than an acre, this double driving strategy shouldn’t provide too much of an inconvenience.

All materials have been delivered and fabricator time has been scheduled.  A YouTube video is planned of the planter in operation putting in June cover crops.

Component 2:  Using cover crops as a weed suppressing mulch to reduce weed control expense.

Summer 2020:  Individual plots of 10 different cover crops were planted at two locations.  The Sun Circle location had a single (June) planting and the Rebarchek location had both a full season planting and an partial season (August) planting of the 10 treatments.  All plots were terminated in Mid-September using a 2’ section of 6” Aluminum C-channel to simulate a roller crimper.  Ropes were attached to act as handles and the technique was to push over the foliage with the C-channel to knock down and then jump on the C-channel to crimp the stems.  After crimping, the C-channel was moved ahead 6” and the process was repeated.  Although time consuming (each site took a day to crimp) the results were adequate:  All foliage was down and crimped at 4-6” intervals.  We modified a technique demonstrated in a YouTube video to meet our needs.  Both locations went into winter with very good amounts of cover on the full season plantings but Rebarchek’s late-season  planting had inadequate biomass in all treatments.

Summer 2021:  Despite going into winter with good levels of biomass covering the surface of each plot, all treatments suffered a high level of decomposition under the snow.  At snow melt in May none of the treatments at either location had adequate levels of residue cover and by normal transplanting date (Early June) all of the plots were a weedy mess.  An interesting observation at the Sun Circle site was that oats, heavily seeded in the walkways to support foot traffic, had very high levels of residue that overwintered.  In consulting with SARE personnel we changes the trial to evaluate the oat straw residue for weed suppression.  All the oat straw from 1/3 of the area was raked and spread on a different 1/3 of the plot giving us three straw treatments:  No straw to serve as a control, 1X straw – the normal level of straw that overwintered and 2X straw- the normal amount plus what was removed form the first plot.  Various brassica crops were transplanted into the three straw levels and observations were made on the level of labor necessary for weed control.  Initially both straw levels (1X and 2X) provided a bit of weed suppression compared to the no-straw plot but within a few weeks both straw treatments also had weeds.  Once these plots needed to be weeded the initial labor savings that had been associated with the early weed suppression was gone because now the straw proved to be a hindrance in efficiently weeding the crops.  In early July the grower made the observation that was more slug damage associated with the straw treatments than in the no reside treatment and she asked us to terminate the trial and remove the residue.

In August at the Rebarchek site an oat density – date of planting trial was initiated.  Beginning in Mid-August oats were planted on a 10 day schedule at 1, 2, 3 and 4 bushels per acre.  Unfortunately, after the second planting the planting sequence had to stop because the entire state was out of oat seed.  By the time replacement seed could be ordered from the Lower-48 a killing frost (Mid-September) stopped all further growth.  At the time of the killing frost all treatments of the Mid-August planting had adequate cover to minimize winter erosion but not enough residue to hinder weed growth in the spring.

Summer 2022:  Building on the observations on the oat trial of 2021, beginning in Mid-August six rates of oats (1,2,3,4,5 and 6 bu/A) were planted on 10 day intervals.  The plots were all hand seeded and incorporated with an S-tine cultivator.  The later 2022 growing season was primarily characterized by record rainfall and cooler than normal temperatures.  The Mid-August planting capitalized on the warmer soil temperatures and all treatments grew wonderfully.  As expected there was more biomass associated with the 4, 5 and 6 bu/A treatments but all plots of the first planting grew well.  The second planting in early September didn’t jump out of the ground as the first planting did and there was significant wildlife damage.  When I arrived at the site to put in the Mid-September planting I flushed over 100 sandhill cranes form the plot.  They were feasting on the newly germinated seeds of the second planting.  While the adjacent first planting showed little damage there was not an oat or a seed to be seen in the second planting.  Luckily, these were migrating cranes and the 3^rd planting that was seeded in Mid-September was not bothered at all.  Although the late-summer and early-fall was cool and very rainy the killing frost didn’t terminate the trial until late October.  At frost termination there was promising amounts of biomass in the heavily seeded treatments of the 1^st planting but only marginal biomass in the crane-affected 2^nd planting and the late (mid-September) planting.