Reducing Water and Fertilizer Inputs by Incorporating Native Beneficial Bacteria in Sustainable Turfgrass Sod Production

Progress report for LNE20-407R

Project Type: Research Only
Funds awarded in 2020: $149,910.00
Projected End Date: 02/28/2023
Grant Recipient: Rutgers University
Region: Northeast
State: New Jersey
Project Leader:
Dr. Bingru Huang, PhD
Rutgers University
Co-Leaders:
William Errickson
Rutgers University
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Project Information

Summary:

Problem, Novel Approach and Justification: Turfgrass sod production is an important component of our diverse agricultural landscape in the Northeast.  In New Jersey, there are 28 sod producers growing approximately 8,960 acres of turf, with annual revenues of $46.4 million in sales and a total economic impact of $66.2 million. Sod growers are continuously looking for ways to improve both plant and soil health while minimizing inputs of water and nutrients to reduce costs and environmental pollution. Some bacteria co-exist within the roots of plants and in soil rhizospheres, and promote plant growth and efficient acquisition of minerals and water while increasing carbon storage in the soil. These bacteria are collectively referred to as plant growth promoting rhizobacteria (PGPR). We have identified several novel strains of PGPR, BurkholderiaNJPB that are native to New Jersey and are effective in improving turfgrass growth under reduced fertility and water deficit conditions in greenhouse and growth chamber trials. However, optimizing this approach for adoption in field conditions by turfgrass sod growers requires additional investigation.

Hypothesis or Question and Research Plan: In order to ensure successful inoculation, such that roots of the plants are adequately colonized by BurkholderiaNJPB to elicit growth-promoting responses, effective inoculation methods must first be identified and selected, including seed treatment, soil drench, and foliar spray. We propose that use of effective inoculation methods and bacterial concentrations will result in greater colonization efficiency and improvement in turfgrass performance in the field with reduced fertilizer and water use. Once the inoculation procedure has been refined, various strains of BurkholderiaNJPB will be applied on turfgrass sod farms, which can improve sod production with less fertilizer and irrigation.  

Outreach Plan: To facilitate the adoption of the sustainable approach of incorporating PGPR as biofertilizers in turfgrass sod production, we will provide educational training workshops or seminars to introduce the most effective colonization and application method, as well as doses and strains of BurkholderiaNJPB to turfgrass sod producers. We will also promote the adoption of this novel approach through extension activities, such as the publication of fact sheets and presentations at Rutgers Turfgrass Field Day and the New Jersey Green Expo, as well as on-site visits and guidance.

Project Objective: 1) To identify effective and efficient colonization methods of turfgrass sod with Burkholderia strains from New Jersey Pine Barrens natural ecosystems; and 2) To determine effectiveness of Burkholderia strains for promoting turf performance, sod quality, and soil health for different turfgrass species under management regimes with reduced irrigation and fertility in the Northeast.

Project Objective:

1) To identify effective and efficient colonization methods of turfgrass with Burkholderia strains from New Jersey Pine Barrens natural ecosystems;

2) To determine effectiveness of Burkholderia strains for promoting turf performance, sod quality, and soil health for different turfgrass species under management regimes with reduced irrigation and fertility in the Northeast.

The information from this project will be applicable for turfgrass sod farms with a goal of reducing inputs for water and fertilizers. 

Research

Materials and methods:

Plant materials and growth conditions:

Creeping bentgrass (Agrostis stolonifera cv. Penncross) plots (1mx1.3m) were established in field soil at the Rutgers University Horticultral Research Farm and maintained at a height of 1.2 cm. Plants were inoculated twice before the start of drought stress and once again upon re-watering using a soil drench method. A rainout shelter was used to cover the plots to simulate drought stress.

Application timing and frequency:

Bacterial inoculant suspensions at the density of 1 x 105-107 cfu/mL (effective dose found in our growth chamber tests) mixed in humic acid (0.01%) was watered into field plots as soil drenching in sufficient volume to moisten the upper 2-inch root zone or as foliar spray. Inoculants were applied at three time points: 1) two weeks before deficit irrigation treatments were imposed 2) The day prior to starting deficit irrigation, and 3) at the time of re-watering following deficit irrigation. The control plants were treated with humic acid (0.01%) without bacteria inoculum in the same volume as bacteria inoculants and were compared to a commercially available inoculant (Quantum Growth). Individual strains and combinations of strains were evaluated.

Inoculation Treatments

Foliar Spray

  • Humic Acid
  • WSF23 + Humic Acid
  • WSF14 + Humic Acid
  • WSF23 + WSF14 + Humic Acid
  • Quantum Growth (commercially available inoculant)

Soil Drench

  • Humic Acid
  • WSF23 + Humic Acid
  • WSF14 + Humic Acid
  • WSF23 + WSF14 + Humic Acid
  • Quantum Growth (commercially available inoculant)

Deficit Irrigation Treatments:

  • Well-Watered Control: Plants were irrigated(100% ET)
  • Drought Stress: Deficit Irrigation (60% ET) for 49 days
  • Recovery: Drought-stressed plants were re-watered for 28 days

Measurements:

  • Turf Quality
  • Soil water content using TDR
  • MSR (NDVI, SI)
  • Light Box (Canopy Density, DGCI)
  • Thermal Images
  • Rooting characteristics
  • Bacteria colonization or viability

Visual turf quality (TQ) was measured at seven day intervals throughout the experimental period. Turf was rated on a scale of 1 to 9, with 1 being brown and desiccated turf, 6 being the minimal acceptable level, and 9 being green and dense turf. Turf quality ratings were based on uniformity, visual attractiveness, leaf color, and canopy density.

A TDR moisture probe was used to take weekly soil mositure measurements from each plot to monitor soil water content throughout the deficit irrigation period. 

Weekly radiometry based objective assessment was conducted using a handheld multispectral radiometer (MSR model CT1000; Crop Scan Inc., Fargo, ND). The MSR measures canopy reflectance characteristics (510-1700 nm) which were used to calculate normalized difference vegetation index (NDVI) and stress index (SI) of the plants.

Light box digital images were collected weekly the experimental period. Image analysis with Sigma Scan software was used to evaluate canopy density (% green cover) and dark green color index (DGCI) throughout the growing season.

Canopy temperature is a good indicator of plant physiological health for stress tolerance, as it estimates transpirational cooling. Canopy temperature was measured using an infrared thermal camera (FLIR). Thermal images werer captured weekly during the trial, and imagery data will be processed using computer software.

Root samples were collected twice for analysis of bacterial inoculation efficiency. The presence of bacterial inoculants in plant tissues are currently determined by both bacterial isolation and quantitative real-time polymerase chain reaction (qPCR) analysis that will be designed based on signature sequences of the 16S rDNA in BurkholderiaNJBP. 

Root samples were also collected at the conclusion of the field season to be evaluated for morphological characteristics such as root length, volume, surface area, diameter, and total biomass.

Research results and discussion:

Plots inoculated with the combination of bacterial strains (WSF14+WSF23) using the soil drench method exhibited increased drought tolerance and post-drought recovery. Preliminary data analysis indicates greater turf quality, NDVI, canopy density, and DGCI in these plots. Figures 1-3 illustrate these differences throughout the growing season.

Bacterial inoculation efficiency data, rooting characteristics, and thermal imaging data are still currently being analyzed.

Initial data suggests that water the bacterial inoculants into the root zone of the plants is more effective than foliar sprays and that a combination of growth promoting bacterial strains is more effective than applying individual strains. Experiments conducted in year two will build upon this information and evaluate seed inoculation methods to develop an optimized protocol for the most efficient inoculation procedure. The optimized methods will be then be tested in the fields of local sod growers.

Participation Summary

Education & Outreach Activities and Participation Summary

1 Webinars / talks / presentations

Participation Summary

250 Number of agricultural educator or service providers reached through education and outreach activities
Outreach description:

The results from the first field season were presented as a poster at the ASA/CSSA/SSSA Annual Meeting, which was held virtually in November, 2020. The poster won first place in the Graduate Student Competition in the C5 Turfgrass Management Division. The abstract is published in the proceedings for this event. 2020 ASA Poster – Bill Errickson

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.