Evaluating On Farm Leaf Composting Methods and the Impacts of Composted Leaves on Germination and Weed Suppression in Rye, Corn and Pumpkins

Progress report for FNE23-036

Project Type: Farmer
Funds awarded in 2023: $24,916.00
Projected End Date: 11/30/2026
Grant Recipient: Longmeadow Farm
Region: Northeast
State: New Jersey
Project Leader:
Bradley Burke
Longmeadow Farm
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Project Information

Project Objectives:

This project seeks to:

1)compare costs of various low input methods of processing municipal leaves. 2)find a balance between the cost to bring compost to a completely finished stage versus  various intermediate stages of semi-finished leaf compost and the costs to incorporate those various stages as soil amendments, 3)determine germination and growth of rye cover crop and cash crops into surface applied leaf compost at various stages of "finish",  4) compare weed suppression of  rye cover crop planted into surface applied compost in various stages of "finish".

Methods Overview:

  1. 4 leaf compost piles constructed to compare the rate of decomposition and cost to establish:  A. control pile no aeration,  B. pile with woodchip plenum layer for passive aeration,  C. pile with vertical perforated pvc pipes for passive aeration, and D. pile using active aeration with a blower and horizontal perforated corrugated polyethylene pipe in the base.
  2. It is anticipated that in the timeframe of one year the resulting compost would be: A. minimally broken down, coarse, mulch like; B. and C. partially finished smaller particles; and D. fine particles, stable finished compost. 
  3. Quantify the germination rate and growth of rye, corn and pumpkins in each.
  4. Compare weed suppression in each.

Leaves are an expensive problem for many NJ communities, and state legislation mandates that they must be separated and recycled. There are some large scale composting facilities, but NJ has extremely limited organic recycling capacities, with distance and tipping fees a cost factor.  On farm composting can reduce the burden on municipal budgets and directly benefit farmers who receive leaves by increasing soil organic matter. However the potential benefits available to the farmer in improvement to soil health and reduction in fertilizer inputs also comes at a cost of time, fuel and equipment.  The more time it takes to process leaves into a usable product, the higher the cost to the farmer.  Our project will look at the cost in both time and dollars of several methods of processing municipal leaves so the resulting product can be utilized.   The question arises- how "finished" does the compost need to be in order for it to be valuable?  Fresh uncomposted leaves are hard to incorporate into the soil.  Fully finished cured compost is the an easy-to-apply soil amendment but requires the most time and cost inputs to produce.  Where is the balance?  Personal experience and observation tells me that partially finished leaf compost is easy enough to incorporate into the soil and also has some benefits as a mulch, including weed suppression.   In order to accelerate the biological activity required for decomposition, oxygen must be incorporated into the piles.  Turning compost piles requires a great deal of time and the use of heavy equipment.  On my farm that chore is often neglected.  A leaf pile that just sits for a year will decompose partially and results in a course product that is still more leaves than leaf mold.  Recommended methods (see references) indicate that even with a minimal number of two turnings during the first year it would still require transfer of the partially decomposed leaves to a curing pile for up to an additional year for curing into a stable finished product.  The time necessary to get a fully finished compost quickly requires turning as often as twice per week for at least several months increasing input costs exponentially and not really feasible.  In this trial we will be looking at low input alternative approaches.  The first method uses a layer of course wood chips as a bottom layer (plenum) with the leaves piled on top.  The course material allows air to flow into the bottom of the pile and move upward through by convection.   A second aeration method involves the use of forced air to oxygenate the piles.  A blower is used to push air through perforated polyethylene drain pipe at the bottom of the pile at timed intervals.  Will the dollar cost for the mechanical apparatus and electricity justify the savings in time, fuel and labor to finished product?  The third alternative is the use of perforated tubes placed vertically in in the windrow allowing passive oxygen diffusion. Different stages of decomposition will be defined and quantified and compared for ease of use.  Past experience suggests that compost can be beneficial as a mulch for moisture retention, soil temperature moderation and reducing weed growth.  On casual observation on my farm it appears that coarse compost left on the surface may indeed provide some weed control but it may also adversely affect the germination of a rye cover crop as well as cash crops planted directly into mulch.  So then what is the best way to use compost together with a cover crop?  Can farmers reduce input costs by eliminating tillage and still get the best growth of the cover?  Can a rye crop be planted into a surface applied layer of compost?  How thick and at which stage of decomposition does the compost allow the best germination?  These are all questions I have considered and feel other farmers have also.  After two years of using a roller crimper on rye cover crop on my farm I have observed some significant reduction in weed growth in both sweet corn and in pumpkins with the mat created by the rolled rye.  This trial will help to determine if there is any better weed control  if the rye cover crop is planted into a layer of compost and whether the number of field passes can be minimized with a particular scenario. Farmers will benefit from learning methods to reduce herbicide use, reducing field passes and applications, which contributes to sustainable on farm practices in many ways from economics to environmental improvements.


Click linked name(s) to expand/collapse or show everyone's info
  • Rick Carr (Educator and Researcher)
  • Kendrya Close
  • Virginia Lamb - Technical Advisor
  • Emilio Panasci - Technical Advisor
  • Laura Tessieri - Technical Advisor


Materials and methods:

From Proposal:

Annually a readily available supply of municipal leaves (approximately 4000 to 5000 cubic yards) is received at the farm in the late fall/early winter.  The material comes from a private recycling company and is brought in on 100 cubic yard tractor trailers from a transfer station where they have accumulated after collection from various communities in northeastern New Jersey.  The leaf piles remain in my compost yard for just under one year with the resulting material being moved to the fields in time to make room for the next season's leaves.

The first part of this project involves constructing four side by side composting trials using low input methods to compare the rate of decomposition and cost to achieve a useable product (without the addition of any high nitrogen materials such as animal manures) using the following methods.  Each pile will be 200 feet long 14 feet wide and 9 feet high.  

a. control pile turned one or two times to achieve proper temperatures but with no other no aeration,

b. treatment pile with woodchip base layer for passive aeration and no mechanical turning

c. treatment pile with vertical perforated pvc pipes for passive aeration and no mechanical turning.

d. treatment pile using active aeration with a timed blower and horizontal perforated corrugated polyethylene pipe in the pile base and no mechanical turning.

The time in man hours will be logged for all phases of the composting process separately for each of the four treatments including construction of each type of pile, assembling mechanical apparatus where applicable, turning the pile where applicable, monitoring temperature and moisture, and breaking down the pile to be spread onto the fields via a tractor and manure spreader.  

It is anticipated that 10 months after forming the piles the compost resulting from the different process methods would be as follows:

a- (control)- minimally broken down, coarse, mulch like,

b- (woodchip base) and

c-(vertical aeration tubes) partially finished compost with smaller particles, and

d-(active aeration horizontal tubes) fine particle stable finished compost. 

The resulting composts will be quantified by visual assessment and Solvita maturity test analysis.    Each compost pile will be monitored for temperatures weekly using 36" manual temperature probes and checked for moisture using a squeeze test.  If lack of moisture becomes a limiting factor moisture can be added to the piles using drip irrigation lines placed on the tops of the piles.  At the end of the time in the yard compost will be assessed for coarseness/fineness based on the percentage of particles above 1 inch, from 1/4 inch to 1 inch and below 1/4 inch using screens.  Five 5 gallon buckets of product will be collected from random locations from each separate treatment pile and mixed together, keeping each treatment separate.  Five gallons of each mixed sample will be weighed.  The samples will be sifted through two screens comprised of 2 foot by 2 foot boxes with screen bottoms. One box will have a 1" X  1" mesh bottom,  the other with a 1/4" mesh bottom.   The coarse material remaining in the 1" screen will be weighed. The medium size material remaining in the 1/4" screen will be weighed.  The fine material that passes through the 1/4" mesh will be weighed.  The percentage by weight of each portion will be determined for each of the four different processing methods.  Comparison of the particle fineness of the four samples will give an indication of how complete the decomposition has proceeded in each pile. The compost from each treatment will be tested for completeness of decomposition by the Solvita respiration test.

The second part of this trial will investigate how to get the best stand of rye cover planted into compost of various stages of decomposition in side by side field trials. 

1- as a control, using existing equipment rye seed will be spun onto 1/2 acre of bare ground using a cyclone spreader and lightly disced to cover the seed. 

2- a set of 4 treatments of 1/2 acre each side by side,  rye seed is spun onto a 2 to 3" layer of compost covering the ground using the material from each of the four process methods and disced lightly into the compost layer.  This second step will provide comparisons of cover crop growth in coarser, less finished compost layer versus layers of finer finished compost.   

3- spinning the rye seed on a 1/2 plot of bare ground and then covering the seed with a 1 inch layer of compost without any discing.  The one inch top layer will be enough to cover the seed and protect it from depredation and drying out but not so much as to act as a mulch that would smother the seed and prevent germination or growth. This last treatment would tell if germination and growth is increased due to direct contact of the seed with the ground versus being disced into the compost layer,  and if seed germination is increased or inhibited by the presence of the compost cover.   

In each of the treatments and the control we would quantify the following factors: 

-Quantify the germination rate and growth of rye in each field plot to determine the effect that the degree of decomposition may have on cover crop growth.  In one square foot grids from 10 random locations in each of the four trial plots the number of germinated rye plants will be recorded in the fall when seedling growth reaches an average of 4 inches.   In the spring after the rye has tillered but before any sign of seed head formation in 10 randomly chosen 1 square foot grids in each trial plot the individual rye plants will be counted and an average height measured. All the rye plants in each grid will be weighed to determine total biomass for comparison of differences among the trials. 

-Compare weed suppression in each of the four treatment plots.    Weed suppression will be observed as either presence or absence of weeds and quantified as the number of weeds and the total weight of the weeds counted in the same 1 square foot areas in 10 locations around the field used to determine spring growth of the rye  (Weights determined using a digital scale).

At the appropriate time in the spring the rye cover crop will be roller crimped and the treatment plots will be no-till planted with sweet corn and pumpkins.  A John Deere max-Emerge no-till planter will be used to plant the sweet corn and the pumpkin seeds.  The seed meters can be set to accurately space the seeds and result in a predetermined number of seeds per foot of row.  Comparison pf germination rates will be determined by counting the number of emerged plants in a given number of feet of row in 10 random locations in each of the treatment plots as well as the control plot.

The same treatments of leaf processing and cover crop establishment will be repeated in the 2nd year of the project.


    The first phase of this project involves comparing the rate of decomposition of leaves using different methods of passive aeration in compost piles

    During October and November of 2023, last year’s leaf compost was cleared from the compost yard and spread on the farm.  This compost was made from 2800 cubic yards of leaves collected in the fall of 2022.  The resulting compost was spread onto 10 acres of crop fields and 5 acres of fruit and nut orchards.

    In October  and November 2023, twelve 30 cubic yard truckloads of wood chips were delivered to the farm at no cost from a tree service company and stockpiled for use in the first trial compost pile.

    Starting December 6 and through December 16, leaves were delivered in 100 cubic yard tractor trailers at the rate of 6 to 10 loads per day as weather permitted.  A total of 4700 cubic yards of leaves were received.  These leaves are collected by a carting company from various municipalities in Northeast New Jersey and  stockpiled temporarily at a transfer yard until final delivery is made to the farm.

    In early December, the wood chips were spread 18 to 24" thick using a 240 bushel capacity manure spreader and a 55 HP tractor to form a base for the 1st trial.  The concept of this pile is that the porous nature of the wood chips allows air to enter through the bottom of the pile and penetrate up through the pile via convection as the compost heats up.  Eight truckloads of leaves were piled on top of the wood chip plenum in a pile roughly 9 feet high by 25 feet wide and 125 feet long.  Man hours and equipment time were logged and tracked for comparisons.

    The second windrow for the vertical pipe aeration trial was formed by starting with a pile of leaves, then leaning 10 foot long perforated PVC pipes onto the pile vertically, then adding more leaves to the pile and repeating.  Pipes were spaced 5 feet apart in each direction in rows of three to create a pile 24 feet wide,  8 feet high and 120 feet long.  Man hours and equipment time were recorded.

    The third pile was the static aerated pile which consisted of four rows of 4" diameter by 10' long pipes with small 1/4" diameter holes drilled every 1 foot apart.  Each of the four rows of pipes spaced 6 feet apart consisted of 75 feet of drilled pipes with additional 10 feet of solid non-drilled pipe at each end.  This configuration allows leaves to completely cover the aeration portion of the pipes and not allow air pressure to leak where pipes are uncovered.  At the terminal end of the configuration the pipes are connected to form a continuous loop allowing any pressure difference in the system to equalize.  At the pressurized end of the system the 4 rows of pipes terminate in an air distribution plenum consisting of a well sealed pressure treated plywood box.  The air plenum is pressurized by a 1.5/1.7 HP blower fan with an automatic timer to provide a minimum of 1 minute of air pressure per hour to aerate the pile.  The "on" time of the blower can be adjusted as determined by temperature monitoring of the pile.  This method of aeration is considered passive because the pile does not require any turning for aeration.

At the time of this report the blower fan is not operating because of delays due to last minute changes in plans and subsequent delivery of electrical components.  Anticipated start up is in a few days.  This aeration design allows for a wider pile.  Overall pile size is 30 feet wide, 9 feet high and 90 feet long.  Man hours and equipment time for forming the pile and constructing the piping system were logged.   The hours for the activities that occur one time in this trial include construction of the air plenum, wiring electric cable from a power source and making electrical connections for the timer and the blower were also accounted for.  

    The fourth pile is a control pile, formed on the ground with no method of aeration applied.  Because there were enough leaves available this year, a 5th pile was formed as a second control pile which will be turned minimally for aeration and mixing.  The additional time required for turning will be recorded for comparison as well as an evaluation of quality of the resulting compost.

    On 12/31/2023 and again on 01/09/2024 a series of temperatures were taken in the piles at four locations at a depth of 36 inches with ReoTemp compost thermometers on the top of each pile and in four locations in the side of each pile. Temperatures will be recorded for each pile weekly to monitor rates of decomposition of the leaves and to compare efficiency of each method employed.

    In review of the work that has taken place thus far, it has become clear that the amount of time that was estimated to get the trial compost piles started was significantly underestimated.  Several areas in particular required time that was just not anticipated. For instance the amount of time to move 300 cubic yards of wood chips to form the base of the first trial pile was unforeseen.  The time it took to plan and build the final incarnation of the air plenum for the static aeration pike was also unforeseen.  There was also a significant amount of time taken to research pipe requirements for the same and sizing of the necessary blower fan, including consultation with experts in the field.  My first attempt to provide power for the blower involved a battery power pack with a solar panel recharging system, which after purchase was found to not meet the specifications claimed by the manufacturer.  That equipment was returned and the plan reverted to running electric cable to supply the aeration system.  Because of lack of foresight on my part and after consulting with an electrician, the size of the cable had to be upgraded and the cable had to be hung above grade from posts set in the ground and overhead over driveways and fence gates.   In these first three months of a two and a half year project, the hours accounted for are already more than 50 percent of the time estimated for the entire project.  It may be necessary to have a review of the expense for labor hours.  However the estimates for materials and supplies seem adequate, and the bulk of those requirements are upfront costs.

Many photos of work in progress have been saved as well as some plan diagrams and can be viewed on request.

Participation Summary
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.