Study of ramial chip mulch and organic fertilizers on wild blueberries

Final report for FNE14-808

Project Type: Farmer
Funds awarded in 2014: $14,706.00
Projected End Date: 10/17/2017
Grant Recipient: Blue Hill Berry Co.
Region: Northeast
State: Maine
Project Leader:
Nicolas Lindholm
Blue Hill Berry Co.
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Project Information

Summary:

There are very few options for organic wild blueberry growers when it comes to fertility management and when an organic grower seeks to promote nutrient uptake and yield for the blueberries with applications of approved fertilizer, it is the weeds who receive the boost, not the blueberries.   Our project studied the effect of one type of mulch material (ramial chips) in tandem with a selected fertilizer package (fishmeal and aragonite), and following three separate applications rates (plus a control) through two harvest cycles (70 lbs./acre of N with fishmeal and 150 lbs./acre of Ca with aragonite vs. 35 lbs./acre of N and 75 lbs./acre of Ca) vs. a control.  It covered four years of study, which began in 2014 and was completed in 2017 (as the production cycle of the wild blueberry is a two-year cycle). 

A general conclusion we immediately reach is that two of the treatments, both the mulch only and the mulch plus half-rate fertilizer application, were not effective in raising nutrient levels or yields over the four year study, and are therefore not recommended.

An unusual correlation we found, one that was opposite to what we were expecting, was the Brix level of the fruit in relation to the yield from each treatment.  So we concluded that lower Brix levels can be seen as indicators of higher yields in wild blueberries.

Our most significant finding was seeing specific gains in foliar and soil nutrient levels from the use of ramial chip mulch plus the full-rate application of organic fertilizers in our study, and a resulting increase in yields in the second harvest after application (2017). 

However, despite these gains seen from the mulch/full-rate fertilizer application, we are not convinced that it is an economically viable practice to continue on our farm, due to the costs involved in this treatment outweighing the gains in revenue after two harvests.  We plan to gather data beyond the funded time of this project, through one more harvest cycle, to make a final determination of its economic viability for us.  If we find after the third harvest that increased revenues from increased yields are profitable, then we will look to replicate and expand the practice of using ramial chip mulch in conjunction with our full-rate application of fertilizers on our wild blueberry fields.  But after two harvest cycles with this project, we conclude that it is not worth the cost of treatment.

Introduction:

Harvest data will be collected during the production cycle years (2015 and 2017); each plot will be completely harvested at one time and the berries processed and weighed with our normal equipment (rakes, field totes, winnower, electronic scale) in our usual manner (for fresh-pack market). The total lbs. of our top-grade and any lower-grade berries will be recorded and entered into a database on our farm.

All of the data collected will show comparisons between the three treatments and our control, with regards to the respective nutrient levels and resulting yields for each plot. We are interested in comparing and contrasting the results of the two different soil tests side by side, and comparing and contrasting those tests to the foliar tests and the Brix readings, and seeing how they all relate to respective yield statistics. A final part of our study would be the examination of the specific fixed costs for the treatments (producing and spreading the chips and buying and spreading the fertilizers) in relation to the resultant yields, to give a picture of the economic impact of the treatments as they correspond to potential yield increases/decreases and profitability

Project Objectives:

Our research objective was to look for measurable results between selected applications of ramial chip mulch and organic fertilizer with respective changes in nutrient levels and yield and cost of production in organic wild blueberry production.  We expect that there will be many divergent findings, and anticipate both beneficial and not beneficial results to be discovered in our various treatments.  Positive results between collected data and the corresponding cost and yield for a given treatment will help organic wild blueberry growers make decisions about mulching options and fertility management.

Cooperators

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  • Marianne Sarrantonio

Research

Materials and methods:

 In 2014, we laid out and established the research plots, and performed all the various treatments for each.  Data collection began in 2015, with the first of our two harvests for the study.

 In late April 2014 I began setting up and laying out our sixteen test plots. Each one was 12’x50′, and I left a 4′ alley between each plot to minimize spillover or “drift” of mulch or fertilizer from plot to plot.  The treatment plots were laid out at random, so neighboring plots vary from each other across the entire study area, which totals about 1/2 acre.  I originally used small plastic flags on fiberglass posts to mark the boundary corner of each plot.

Prior to laying out and establishing the plots, most of the study area had been mowed (a standard pruning technique), while the rest of the five acre field was burned (the alternative pruning technique).  Our study originally proposed having the test plots all in the similarly managed area of the field, to reduce the number of variables that could affect our results.  Unfortunately, the 16 test plots could not readily fit within the mowed area of the field, so I established four of the plots in an area that was burned (one replication of each treatment).  The different pruning techniques may or may not alter the plant growth and yield –but either way, I have clearly noted on the test map of the plots which ones had been mowed and which ones had been burned.

Over a four week period in May, I cut saplings (predominantly gray birch) on our farm from areas where they’d become densely established over the past 20 years, thereby opening up former field space.  Most of the  saplings were smaller than 3″ in diameter, not yet leafed-out, and everything up through the tiniest of branches was chipped, resulting in what is known as “ramial chips.”

The ramial chips were then spread to a depth of 2″ to 4″ on twelve of the 16 test plots (our control treatment in the study, replicated across four plots, has no mulch or fertilizer applied).  In low spots and hummocky areas, I often allowed the mulch to accumulate to depths up to 8″, thereby helping to level out the surface of the field, a condition which helps make future harvesting and pruning work more efficient.

Just prior to spreading the mulch on eight of the plots (the ones where I had planned the replications of two different treatments of fertilizer applications), I spread the appropriate amounts of fishmeal and aragonite.

One treatment over four plots had a rate of 12 lbs./plot (or the equivalent of 70 lbs./acre of N) of the fishmeal and 2 lbs./plot (or 150 lbs./acre of Ca) of the aragonite.  The second treatment over four plots had half those rates (6 lbs./plot of fishmeal or 35 lbs./acre of N and 1 lb./plot of aragonite or 75 lbs./acre of Ca).  The fertilizer was weighed in a hanging scale, and spread evenly over the plots by hand.  Then, the ramial chips were immediately spread over the top of the fertilizer.

I found the work of producing and spreading the ramial chip mulch to be accomplished in less time than I had estimated.  Although it is time-consuming and difficult work, I am happy in light of developing enterprise budgets for this study that the labor costs could be lower than originally thought.

By the time I was chipping and spreading the ramial chip mulch on the last few test plots, the gray birch saplings had begun to leaf-out, which could alter, among other things, the C:N ratio of the ramial chips, and therefore change their chemical, biological and/or physical attributes in the study.  This may or may not have had an affect on the results of our project, but either way, I noted these plots on the test map of our field.

Our original proposal included gathering baseline data during the first summer of the study (2014), including soil test analyses, foliar nutrient analyses, and Brix readings of foliage from each plot.  Due to illness and an extremely busy farm season (it was a banner year for the wild blueberry harvest), I was unable to perform these tests.  This is unfortunate, as it will not be possible to compare the results of later tests with the starting data.  However, I did have some data (soil and foliar analysis) from this field from 2010, which I will be able to use, as well as the harvest data from the field going back to 1998.  Our final analyses and outcome for the project is primarily comparative, treatment to treatment, so the baseline data, though important and interesting, is not imperative; all of the plots are in the same limited area within a field that has been managed in the same manner for almost 20 years.  I do plan on performing all of the tests on all of the plots from now on, as originally proposed.

Finally, for 2014, I realized by late summer that the marking flags I had chosen were not going to be sufficient for a four year study.  Some of the flags had already torn, and most had faded dramatically in the sun; there were also several that had blown over or been lifted out.  So, I purchased some iron rod rebar, cut it to 2′ lengths, spray painted these new stakes in four different colors (to mark and correspond with the four different treatments), and installed them in replacement of the original corner boundary markers.  These stakes are more permanent for our study, and give instant identification as to which treatment one is looking at for each plot (as they are now noted on the test map).

2015 saw the first harvest year in our study allowing us to begin the gathering and analyzing of data.  

We successfully gathered useful data from the first of the two harvest cycles that this study encompasses (the second harvest cycle will be in 2017).  The data includes harvest yields from each test plot, which have then been analyzed, as well as Brix readings from the ripe fruit taken from each plot.

In mid-May, we set four hives of honey bees on the field for a period of several weeks while the blueberry plants were in bloom, and had good weather plus notable healthy numbers of native/wild pollinators to ensure good pollination for the year.  Just prior to harvesting, in late July, we strung the boundaries of each of the sixteen plots (with white string) to clearly mark the edges of each.  On August 3rd, we harvested the blueberries from all of the alleys between and surrounding the plots; then on August 4th and 5th, we harvested the plots.  The berries from each plot were harvested into clearly marked field totes, which were then gathered together and brought to our winnower shed.  The field totes from each individual plot were then processed through our fresh-pack line (i.e., winnower), and the total weight of processed berries from each plot then measured and recorded.  At this time, a small sample was taken from each plots’ winnowed berries, which were then placed in labeled zip-lock bags in our cooler; several days later, we used our refractometer to measure and record the Brix level of each sample.  All of these numbers have been gathered and analyzed in several matrixes, and now serve as the foundation set of data which will be compared and contrasted to our pre-test baseline data and the second set of test data yet to be collected.

Due primarily to continued personal illness (Lyme disease), we were not able to perform all of the data gathering from our original proposal this year.  Namely, we did not collect weekly Brix readings of the fruit for up to five weeks (from early ripening through harvest), but rather only collected the one Brix reading at harvest.  Also, we were not able to collect Brix readings from the plant tissue from each plot.  

In 2016, after a successful prune (by fire), we successfully gathered useful data from the second of the prune cycles that this study encompasses (the first prune cycle was in 2014).  The data includes wild blueberry foliar analyses from each of our 16 test plots, as well as soil samples of each plot that were analyzed by two separate soil testing labs.

In March, we spread straw over the entire field (about 4 acres in total), spreading it evenly at a rate of 40 bales/acre.  Then on the first of May, we burned the field, setting the straw alight with a drip torch and containing the burn with a small crew using backpack water-pumps.  It was a good, even burn, which resulted in a very vigorous and healthy sprouting and regrowth over the summer.  It was a rather dry summer, with less than average rainfall, which may impact the size and number of buds set for next year’s harvest —we will just have to wait and see, and compare next summer’s yield data with this sort of natural phenomenon in mind.

It was quite apparent that the ramial chip mulch, that had been spread on most of our test plots (except the control plots) back at the beginning of the project in 2014, had begun to break down and disintegrate into the soil;  we are hopeful that this continuing decay means that the mulch will no longer hinder the physical act of harvesting next summer's crop (as it did in 2014) and that perhaps it will not be tying up as many nutrients as one expects it does in the earlier stages of decomposition.

On July 12, when the new sprouts were in the “tip die-back” stage, we cut about 100 stems of the wild blueberry plants from each plot, as required by the Univ. of Maine testing service, which were then bagged and labeled and shipped to the lab.  The results (a nutrient analysis of the plants, which is used by wild blueberry growers for recommended soil amendments and fertilizing rates) were received in November.

In late September, we used our soil core sampling tool, and took two boxes of soil samples from each plot.  These boxes were labeled and then shipped (one sample from each plot) to two separate soil testing labs —one at the Univ. of Maine, the other one at Perry Agricultural Lab in Bowling Green, MO.  As we proposed in our original grant application, the standard soil test (Univ. of Maine) will give accurate pictures of the total nutrients present in the soil, while a Ream’s-type test (Perry Agricultural Lab) will give more a picture of what amounts of nutrients are readily available for the plant roots to take up, and checks both ammonia and nitrate nitrogens.  The results of these tests, including soil pH, Cation Exchange Capacity (CEC), and soil nutrient levels, were both received in early November.

All of this data has been gathered and analyzed, and now serve as the second set of data of foliar and soil nutrient levels which will be compared and contrasted to our pre-test baseline data (to be presented in our Final Report, next year).

In 2016, we purchased a stainless steel hydraulic press, needed to extract juice from the wild blueberry plants for refractometer readings of their Brix level.  Due to the manufacturer’s (Pike Agri-Lab) delay in needing to construct and assemble the unit, we did not receive it until late summer —too late to do the weekly sampling and testing that we had intended and wanted to do from our proposal.

In 2017,  we had our second harvest for this project, and collected data on the lbs. of organic wild blueberries harvested under each treatment, and the Brix levels of the ripe berries from each treatment.

Research results and discussion:

SARE Data Summary 1 pdf

SARE Data Summary 2 pdf

The two attached Data Summary charts capture the results of our study, showing the results of our foliar nutrient tests, our soil nutrient tests, our Brix tests of the fruit, and our economic analyses for each of the four treatments, over the four year study.  The data is displayed in rows, with the highest or most valuable result being highlighted in red, and in some cases the lowest or least valuable result being highlighted in green.

A general conclusion we immediately reach is that two of the treatments, both the mulch only and the mulch plus half-rate fertilizer application, were not effective in raising nutrient levels or yields over the four year study, and are therefore not recommended. 

An unusual correlation we found, one that was opposite to what we were expecting, was the Brix level of the fruit in relation to the yield from each treatment.  Since sucrose levels in plants (and fruits) are generally regarded as indicators of health and good nutrition, it was our expectation that high yields would correspond with high Brix.  Yet in both harvest years, we found that the highest yielding treatment had the lowest Brix.  One of the ag educators we have shared this data with suggested that a larger yield is often the result of larger sized fruit, which have a higher flesh to skin ratio, and therefore have lower levels of sugars (which are found in the skin) --and a smaller yield from small fruit will have a lower flesh to skin ratio, or higher sugar levels.  So with this in mind, we conclude that lower Brix levels can be seen as indicators of higher yields in wild blueberries.

Our most significant finding was seeing specific gains in foliar and soil nutrient levels from the use of ramial chip mulch plus the full-rate application of organic fertilizers in our study, and a resulting increase in yields in the second harvest after application (2017).  This is good news.  This can be quickly observed in our data summaries by all of the red highlighted figures that one sees in the mulch/full-rate fertilizer column on the far right.  Further detailed discussion of these nutrient tests can be read in our 2016 report (below).

However, despite these gains seen from the mulch/full-rate fertilizer application, we are not convinced that it is an economically viable practice to continue on our farm, due to the costs involved in this treatment outweighing the gains in revenue after two harvests.  We plan to gather data beyond the funded time of this project, through one more harvest cycle, to make a final determination of its economic viability for us.  If we find after the third harvest that increased revenues from increased yields are profitable, then we will look to replicate and expand the practice of using ramial chip mulch in conjunction with our full-rate application of fertilizers on our wild blueberry fields.  But after two harvest cycles with this project, we conclude that it is not worth the cost of treatment.

 

The collected data from this first harvest year, though interesting and compelling, has not given us the ability to draw any strong conclusions, which does not surprise us and underscores the value of having secured research funding through two harvest cycles.  What we have found in this first year’s work is that the efficacy and impact of our treatments will take some time to express themselves clearly, and that although there are some clear differences in comparing different treatment plots’ data, there is no clear relationship between any given treatment and any given result. 

In general, there are still many naturally occurring factors which could reduce or make any statistical significance between the harvest data or the Brix readings from the various plots very slight.  These factors include the genetic traits of the blueberry clones themselves in any given plot or area of the field, plus the underlying soil type, and naturally occurring weeds present, etc.  All of these factors were expected to influence yield and nutrient data, and we randomized our plots to allow for such natural variation.  Nonetheless, we have observed such things as an area of our field where five adjoining plots have the highest yield data, and another area of our field where five adjoining plots have the lowest yield data.  What’s more, the ramial chip mulch is still very present (not decomposed or otherwise broken down) and is therefore negatively impacting the ease and ability to cleanly harvest the ripe berries, and is likely tying up nutrients in the soil as it continues to decompose.  We hope and expect these conditions to change, and the data resulting from the harvest in 2017 to reveal more telling relationships to our treatments.

Here are some of the more interesting analyses from this year’s data:

  1. The control plots (no treatments) had the highest yield overall (total of all four plots), with 149.93 lbs. total, and average of 2,717.48 lbs./acre equivalent.  That compares to the mulch only plots with 135.76 lbs. total and 2,460.65 lbs./acre, the mulch and half-rate fertilizer plots with 130.30 lbs. total and 2,361.69 lbs./acre, and the mulch and full-rate fertilizer plots with 127.56 lbs. total and 2,312.03 lbs./acre.  Again, we believe the mulch may still be negatively effecting the yield and will wait to see what the second harvest year’s data reveals.
  2. There was very little difference between plots that had been burned (as a pruning technique) and those that had been mowed.  The burned plots averaged 33.75 lbs. total each and 2,449.89 lbs./acre, while the mowed plots averaged 34.05 lbs. total each and 2,471.85 lbs./acre.
  3. There was a slight difference between plots that had been mulched with proper ramial chips (made with dormant, non-leafing hardwood) early in May of 2014 and plots that had been mulched with hardwood that had already leafed out later in May 2014 (a condition which we believe effects the C:N ratio of the chipped wood, and therefore the chemical, biological and physical properties and effects).  The non-leafed out ramial chip mulched plots averaged 37.10 lbs. total each and 2,693.10 lbs./acre, while the leafed-out ramial chip mulched plots averaged 28.51 lbs. total each and 2,069.71 lbs./acre.  The proper ramial chips appear to have better effect.
  4. The Brix readings of the ripe fruit from the mulch only plots averaged the highest, with an average of 11.3.  The mulch and full-rate fertilizer plots had a 11.1 Brix average, the mulch and half-rate fertilizer plots had a 10.6 Brix average, while the control plots had the lowest Brix average of 10.2.  These are all lower than baseline data we have from previous years’ ripe fruit which is typically between 12 and 14 Brix.
  5. The highest yielding plot was a control plot with 55.44 lbs. total (4,024.94 lbs./acre equivalent).  The lowest yielding plot was a mulch and full-rate fertilizer plot with only 23.57 lbs. total (1,711.18 lbs./acre).  The highest Brix reading came from a mulch only plot with 12.2.  The lowest Brix reading came from a control plot with only 9.8.

Nothing new to report.  As with last year, we have continued to engage in conversation about this project with other wild blueberry growers, extension agents, and other intersted parties, at farm meetings, MOFGA meetings and events, etc.  Our outreach plan remains as first proposed.

In 2016, we found that there were some significant measurable results between our control plots and the test plots where we had applied the ramial chip mulch plus the full-rates of fishmeal (70 lbs. N/acre) and aragonite (150 lbs. Ca/acre).  The positive relationships were observed in both the foliar analyses and the soil analyses.  The following list highlights the changes found in the mulch/full-rate fertilizer plots vs. our control plots:

     -slight increases (2 to 8%) in most of the major nutrients, as measured in the foliar tests, including Nitrogen, Calcium, Magnesium, and Phosphorus.

     -increase (7 to 10%) in some micronutrients, as measured in the foliar tests, including Boron and Zinc.

     -increase (3 to 20%) in the Cation Exchange Capacity (CEC), as measured in the soil tests, from both the Maine soil lab and Perry Ag lab.

     -significant increase (60 to 100%) in Calcium, as measured in the soil tests, from both the Maine soil lab and Perry Ag lab, observed in both lbs./acre and %saturation.

     -significant increase (37 to 39%) in Phosphorus, as measured in the soil tests, from both the Maine soil lab and Perry Ag lab, observed in lbs./acre.

     -significant increase (19 to 45%) in Magnesium, as measured in the soil tests, from both the Maine soil lab and Perry Ag lab, observed in both lbs./acre and %saturation.

     -significant decrease (43 to 47%) in Sulfur, as measured in the soil tests, from both the Maine soil lab and Perry Ag lab, observed in lbs./acre.

Other differences we found between the mulch/full-rate fertilizer plots and our control plots, which are not as clearly positive at this time, include the following:

     -slight increase (5 to 6%) in soil pH, as measured in the soil tests, from both the Maine soil lab and Perry Ag lab.

     -decrease (8 to 32%) in many micronutrients including Iron and Manganese, as measured in both the foliar tests and the soil tests from both the Maine soil lab and Perry Ag lab.

In general, we see that our fertilizer has effectively reached the plants and is available in the soil at higher rates in our mulch/full-rate fertilizer plots than in our control plots.  This will hopefully lead to higher yields in these fertilized plots, though next summer's data will determine this.  We are also interested to find that the pH has increased in the mulch/full-rate fertilizer plots and that the Sulfur levels have gone down compared to our control plots, and will be reading about and researching these relationships over the next year, and considering their implications for future replication of this type of mulch/fertilizer process.  

Interestingly, there are no consistent relationships to be observed in this year's data between the mulch only plots or the mulch/half-rate fertilizer plots and our control plots.  Again, this year's nutrient-focused data will be most relevant to us only when analyzed further in relationship to next summer's yield data, Brix readings, and then compared to our baseline data from the past.  Our final report, next year, will also include some budget analyses so that we can determine if any of our experiments are cost effective.

As with last year, we have continued to engage in conversation about this project with other wild blueberry growers, extension agents, and other interested parties, at farm meetings, MOFGA meetings and events, etc. 

Research conclusions:

By the end of 2017, the second harvest year, we found a slight increase in yield from our test plots where we had applied the ramial chip mulch plus the full-rate of organic fertilizers compared with the yield from our control plots (1,680 lbs./acre in the mulch/full-rate fertilizer plots compared to 1,639 lbs./acre in the control plots).  This additional yield, at our current pricing, brings additional revenues of about $190/acre for this harvest.  But when combined with the first year's harvest data and the cost of the treatments, we find that as an enterprise, the application of ramial chip mulch plus the full-rate of fertilizers is not cost effective or profitable (costing $1,669/acre for inputs not including labor while averaging 182 lbs./acre lower yield than our control plots over the two harvests).  Despite this cost-prohibitive finding, it is important to note that we have seen improved nutrient availability reflected in both the foliar and soil analyses from the mulch/full-rate fertilizer plots, and see that that has resulted in improved yields, but we will need to follow this project for another harvest cycle (unfunded) to determine if greater yields will be met and perhaps a profitable margin of revenues above costs attained.

Participation Summary
1 Farmer participating in research

Education & Outreach Activities and Participation Summary

1 Webinars / talks / presentations

Participation Summary:

15 Farmers
2 Number of agricultural educator or service providers reached through education and outreach activities
Education/outreach description:

I gave a presentation at the Farmer to Farmer Conference, on Nov. 5, 2017, during a workshop I had help organize entitled "Strategies for Optimizing Yields in Organic Wild Blueberries."  The workshop was attended by at least two ag educators and 15 farmers.  My presentation included a lengthy powerpoint show of this SARE project, with photos of my work over the four years plus tables and data of my findings.  Many of the farmers requested copies of the data.  Also in attendance at this workshop was the editor of the MOFGA newspaper, and she confirmed her interest in my writing a full-length article on this project, which I am intending to complete for publication some time in spring or summer 2018.  Finally, I intend to host one of the annual organic wild blueberry growers' meetings, organized by MOFGA and Univ. of ME Extension, some time in the next couple of years, which will bring many farmers and ag educators to my farm for a site tour of the research plots and the project as it continues after the SARE funding ends.

Learning Outcomes

16 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key areas in which farmers reported changes in knowledge, attitude, skills and/or awareness:

The costs of spreading the ramial chip mulch and fertilizers ended up being too cost prohibitive in the four-year (two harvests) scope of this study, which dismayed many of us. The beneficial use of wood chip mulch in wild blueberry production is well known, as it is usually advised for filling in bare spots in fields --so there has been much discussion on how to procure and spread wood chips more cost-effectively (namely, by asking road crew chippers to dump their chips for free at the farm, instead of making one's own chips). This may be the best advisable solution, though different types of chip material will act differently than our study.

It is indeed good news that we found in our study that we can increase the nutrients, both in the soil and in the plant foliage, through the application of ramial chip mulch plus fertilizers. We also found that the yield can increase by the second harvest after application. But also of great significance, we have observed that we have not increased the weed pressure or weed population with the treatments. There is great interest to follow the project for at least one more harvest cycle.

Project Outcomes

1 Farmers changed or adopted a practice
Project outcomes:

This study has proved of great interest to many organic wild blueberry growers and ag educators/extension personnel.  It focuses on one of the biggest issues for us: increasing yields through fertility management without increasing weeds.  We feel that we have reached a level of success with our findings, seeing that we have increased nutrient levels/availability within the soil and within the plants, and have increased the yields through one of our treatments, without increasing weed populations --something that has not been done before.  With the ramial chip mulch and full-rate fertilizer application, the organic wild blueberry plants have successfully beaten the weed competition to the nutrients, been given a fertility boost, and have produced a bigger crop.  On our farm and on other farms and experimental plots, this treatment can now be tried in other variable configurations, with the main focus being on reducing the costs of the treatment or otherwise finding an acceptable return/profit margin for the treatment.

Assessment of Project Approach and Areas of Further Study:

One of the great benefits of receiving funding for this type of research is that it allows you to take the time to try some tasks or techniques that otherwise you know you could not afford to do.  In this case, we spent a great amount of time cutting saplings and chipping them and spreading the chips on our field plots.  The labor it took to do this work is not cost-effective for the results that we observed through two production cycles, though several benefits were found.  We have discovered that wood chip mulch being used in conjunction with organic fertilizer applications can increase nutrients in both the plants and the soil, and increase yields, but not profitably in the way we did it.  So, we would like to see further experiments with similar approaches that aim at reducing the costs of the treatments.  Perhaps this can be done using "waste" wood chips from road-side crews, or from purchasing the organic fertilizers in larger quantities/bulk from other sources that would be less expensive, or perhaps there are other ways.  Since we now know that we can feed the wild blueberry plants successfully without unduly feeding the weeds, we will continue to follow the practice of using mulch and selected organic fertilizers in new and various ways.  Other blueberry growers, whether wild or cultivated, could also continue experimenting with this combined treatment, looking for both nutrient and yield boosts and a cost-effective result.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.