This is an innovative project that aims to enhance understanding of biochar’s impact on both field and container nursery production. Working directly with nursery growers in Suffolk County, our goal is to evaluate if biochar can contribute to on-going agricultural stewardship efforts by increasing nutrient availability and soil water retention, and decreasing leaching losses. The knowledge gained would increase accuracy of biochar use recommendations and rates for nursery producers both within the County and regionally.
The goal of this study is to investigate the effects of biochar on nutrient availability and uptake and soil water retention in field and container nursery production. We hypothesize that biochar amendments will enhance moisture status and nutrient uptake by the crops, and hence, decrease runoff and leaching losses ultimately contributing to on-going agricultural stewardship efforts in Suffolk County. We also hypothesize that biochar application rate will impact soil water and nutrient retention, with retention increasing as biochar application rate increases.
Field experiments were established at one privet nursery and one Christmas tree farm in 2019. The second field trial will be established at another privet nursery in 2020. Container experiments were established at the Cornell University Long Island Horticultural Research and Extension Center (LIHREC) and a local nursery on the North Fork of Long Island. In April 2019, a preliminary biochar column test was conducted using four different biochar types and a typical sandy loam soil from LI to evaluate which biochar type resulted in the greatest water retention. Results of this preliminary column test supported the use of a hardwood biochar in the field and container experiments. The hardwood biochar came from ARTiChar – Advance Renewable Technology International (Prairie City, IA). All the biochar material was inoculated for five days in a compost tea solution. In June 2019, both the container and field trials were established.
Biochar was substituted into the growing media at rates of 10, 20, and 30% by volume. Biochar was incorporated using two different methods (mixed versus layering at the bottom of the substrate). Containers with no biochar served as the control group. Treatments were marked as B10 (biochar at bottom 10%), B20 (biochar at bottom 20%), B30 (biochar at bottom 30%), C (no biochar control), M10 (biochar mixed into media at 10%), M20 (biochar mixed into media at 20%), M30 (biochar mixed into media at 30%). The experiment was arranged as a completely randomized design with each container serving as the experimental unit. Plants studied included boxwood (Buxus Green Mountain), California privet, and switchgrass (Panicum virgatum “Heavy Metal”) and LIHREC and only switchgrass (Panicum virgatum “Heavy Metal”) at the local nursery. Biochar treatments were applied at the time of planting into 1.5 gallon plastic containers in July 2019 for the privet and June 2019 for the switchgrass and 3 gallon containers for the boxwood. The media was a professional grow mix of 35-45% softwood bark with sphagnum peat moss, vermiculite, dolomite limestone, and a wetting agent.
The PourThru procedure was conducted weekly on all container plants between mid-June and the end of September. This procedure allows for continuous monitoring of container pH and EC levels so plant nutrient status could be monitored and adjusted as needed. Plant heath evaluations of the boxwood plants occurred once per month during the summer on 7/15/2019, 8/19/2019, and 9/9/2019. Data on leaf miner and leaf spot prevalence were collected and an overall plant health rating was given on a scale of 1 to 5. Plant heath evaluations of the switchgrass plants occurred during the summer on 7/15/2019, 8/5/2019, and 8/19/2019. Data on number of flower stems per plant, disease, chlorosis, and overall plant health were also collected. Total leachate was collected from the boxwood and switchgrass containers twice in September and twice in October to measure ammonium and nitrate concentrations. Destructive sampling of the switchgrass containers at LIHREC occurred mid-September to evaluate differences between treatments on shoot and root growth in year one.
The field experiments were established using a completely randomized block design with subsamples. Ten consecutive plants per treatment was set as the experimental unit. Prior to biochar application soil samples were collected from each farm. Biochar was applied at rates of 5, 10, and 15 tons/acre and a no biochar control for a total of five replications per treatment to California privet (Ligustrum ovalifolium) and Douglas fir (Pseudotsuga menziesii). One week after applying the biochar, lysimeters were installed in two of five replications in each treatment at both field sites. The two cooperating growers followed their standard practices for weed management and fertility throughout year 1 of the trial.
Additional data was collected on the number of terminal buds on the leader and height for the Douglas firs. Soil health samples that measure the soils physical, chemical, and biological properties were collected from all field sites prior to biochar application. The soil health samples will provide growers with a comprehensive assessment of the quality of their soil and provide them with both short- and long-term management suggestions. Time domain reflectometer (TDR) probes were installed at the two field trials established in 2019 to continuously record soil moisture, electrical conductivity (EC), and soil temperature.
Mina Vescera potting up switchgrass for the biochar container trial
No differences were found between treatments on shoot growth (Figure 1). Root biomass weight included the weight of the potting media because it could not be separated. Treatment B30 produced significantly more root biomass than B10. No other differences were found between treatments on root biomass.
No trends were found for ammonium and nitrate leachate concentrations based on treatment for both boxwood and switchgrass plants.
Overall plant health ratings of container plants in year 1 were either 4 or 5, meaning little to no disease issues.
Pictures of all container boxwood and switchgrass plants were taken on 8/20/2019 to visually compare treatments. No visual differences were seen from these side-by-side pictures.
PourThru data (EC and pH) were collected throughout the season. No differences were found between treatments over the season.
Lysimeter samples were collected from late July to late October from the Christmas tree and California privet production fields. The low-tension, porous-cup lysimeters functioned well in the loamy soils of the Christmas tree production soils, but not in the sandier soils of the California privet production fields. We believe fewer samples were collected from the privet-field lysimeters because the soil was too free-draining at the 18-inch depth location of the porous cup. In 2020 we plan to install shallow low-tension lysimeters to improve data collection. Fertilizer practices differed by grower. For the Douglas fir trees, a low rate of slow-release, organic fertilizer (3% N) was applied at a rate of 0.1 oz N per tree three times during the growing season (May, June, and September). For the California privet shrubs, one application of conventional, quick-release fertilizer (16%N) was applied in early July at 500 pounds to the row-acre. Table 1 lists ammonium (NH4) and nitrate (NO3) nitrogen levels detected in field lysimeters located at the Christmas tree farm in Douglas fir production fields. Table 2 lists ammonium (NH4) and nitrate (NO3) nitrogen levels detected in field lysimeters located in the California privet production fields.
Table 1. Ammonium and nitrate nitrogen levels detected in Douglas fir production fields from July 2019 to October 2019, Long Island, New York.
|15 T/A||18.9||17.0||18.5||15.7||19.5||17.1||0.5||2.1||< 0.1|
*TRT represents “treatment.”
T/A refers to “tons/acre.’
Table 2. Ammonium and nitrate nitrogen levels detected in California privet production fields from July 2019 to October 2019, Long Island, New York.
Shoot and root data for both species are currently being summarized.
Education & Outreach Activities and Participation Summary
An article providing an overview and explanation of the project was published in our monthly agricultural extension publication (Ag News). This publication is mailed to approximately 325 growers monthly. The article is entitled “New study will look at biochar impacts on water and nutrient retention in nursery production.”
Ag News article April 2019
An overview of the project including a discussion about biochar and soil moisture sensors was given to nursery growers attending Cornell University’s annual Plant Science Day at LIHREC in July 2019.
Mina Vescera attended the Northeast Specialty Crop Water Symposium in December 2019 at the University of Vermont where she presented an overview of biochar and the field trials associated with this project. Talk titled “Evaluating wood-based biochar in field production of woody ornamentals in Long Island nurseries”.
A field day will be held in 2020 to introduce other growers to biochar. This field day will provide other growers with a hands-on opportunity to learn how to practically use and apply biochar as well as a visualization of its effects on crops
A nursery/landscape/golf course manager from western Long Island is now aware of biochar and its potential benefits and plans to incorporate it into his managed landscapes in the future