Recipient Organization
PENNSYLVANIA STATE UNIVERSITY
208 MUELLER LABORATORY
UNIVERSITY PARK,PA 16802
Performing Department
Ecosystem Science & Management
Non Technical Summary
Riparian forest buffers consist of woody vegetation directly next to a surface water body that helps protect this water from potential sediment and nutrient loss from land practices (agricultural, residential, urban, etc.), which currently is a large concern within the Chesapeake Bay Watershed. This vegetation and soil within these buffers can absorb both surface and subsurface water and decrease nutrient and sediment transport within a relatively narrow width of land (typically 20-100 meters). However, there are portions of the landscape where water concentrates called concentrated flow paths. These paths typically have too much water flowing through too narrow of land during and immediately after rain events for the riparian forest buffer to absorb, resulting in erosion within the buffer and decreased water quality benefits. There is a need to reduce the volume of water transported within these concentrated flow paths to 1) increase the amount of water treated by the riparian forest buffer, 2) protect the riparian forest buffer from surface erosion, and 3) reduce the impact of downstream flooding by slowing the surface water down. Wood-based biochar, wood that is heated under high temperatures (500?C) with no oxygen to avoid burning, application to soil has been shown to impact soil physical properties that influence the amount of water that can infiltrate into the surface of the soil. There is potential that biochar application to the soil within a concentrated flow path could increase infiltration and decrease both erosion and riparian forest buffer bypass flow. However, there currently is little research done on plot-sized, in-field studies to assess this impact. This research is crucial to develop a best management practice centered around biochar to help treat surface water after large precipitation events.This proposed project will assess three concentrated low paths located on agricultural land that concentrate water into riparian forest buffers. Three 0.1 acre plots will be established in each concentrated flow path that will have the following treatments: control (leave this plot under the current management), tillage (till at the beginning of the experiment), and tillage + biochar (add biochar to the soil and then incorporate with tillage). Soil will be sampled throughout the two-year experiment to assess any physical property changes based on treatment. Briefly, this includes how much empty space there is between soil particles, how resistive the soil is to water erosion, and the degree to which the soil repels droplets of water. These properties all impact water infiltration and have been shown to change after biochar application. Biochar can increase the void space in soil to allow more water to infiltrate, increase soil's resistivity to water erosion allowing increased water infiltration, and temporarily increase the repellency of water within soil which potentially decreases the amount of water that can be absorbed over the short term. In addition to these soil properties, this proposal will also directly measure soil water infiltration rates approximately monthly and after rain events as well as the cumulative yearly nutrient downward movement within each plot. All sampling will be done within all three plots for the three concentrated flow paths so that the results can be directly compared. Through these methods, the goal is to assess whether wood-derived biochar applied to the soil can increases the amount of water infiltration and therefore mitigate the erosive nature of concentrated flow paths within riparian forest buffers. An increase in soil water infiltration within the plots that have biochar applied will be considered a favorable outcome in reducing erosion and downstream flooding potential.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
Main Goal: Provide the initial steps in scientific discovery towards assessing biochar's ability in mitigating agricultural surface runoff, especially focused on concentrated flow paths (CFP).Objective 1: Establish biochar application trial plots on agricultural CFPs directly adjacent toriparian forest buffers for this proposed and future biochar research assessing biochar as a best management practice.Objective 2: Determine impact that biochar application has on soil surface infiltration withinagricultural CFPs by measuring surface infiltrate rates and important soil physicalproperties for promoting surface water infiltration including bulk density, particledensity, porosity, wet aggregate stability, and hydrophobicity as well as determine the texture of the soil.Objective 3: Determine potential water quality implications from this biochar application byanalyzing leached nutrient ions (ammonium, nitrate, and phosphate) using resinlysimeters within the soil profile under the biochar application.
Project Methods
The research outlined in this proposal will take place on three concentrated flow paths originating on agricultural land that lead into riparian forest buffers of varying stand age. Two of the concentrated flow paths occur on land in corn and soybean row crop rotation, while the third flow path is on a dairy farm's pasture which is actively grazed. The concentrated flow paths will be separated into three, 0.1 acre plots and randomly assigned a treatment (control, tilled, and tilled + biochar). The tillage depth will be approximately 30 cm. The biochar used to amend the three 0.1 acre tilled + biochar plots will be made up of Central Pennsylvania small particle mixed hardwood pyrolyzed at 500 degrees C and will be incorporated at a rate of 2.5% by weight. Tilling the biochar will help incorporate the material into the soil for maximum soil-contact and impact on soil physical properties.Each of the treatment plots within the three concentrated flow paths will be assessed for physical properties that influence water movement as well as surface water infiltration rates. The soil physical properties focused on in this study include bulk density, particle density, total porosity, wet aggregate stability, and soil hydrophobicity. These physical properties will be measured according to recognized standard operating procedures. Bulk density samples will be collected with an AMS bulk density sampler equipped with a compact slide hammer. The sample will be taken back to the lab and oven dried at 105 degrees C until constant weight is obtained. This constant weight will be divided by the volume of the container it was sampled within to obtain a density (g cm-3). Particle density will be collected via the pycnometer method from Grossman and Reinsch, 2002. After both bulk and particle density are measured, the numbers collected for each soil sample collected will be used to calculate the total porosity with equations 1 and 2. The current understanding of adding biochar to soil indicates a decrease in bulk and particle densities due to biochar having a lower densities (bulk-0.1 to 0.3 g cm-3; particle-1.5 to 2 g cm-3) than those known averages for soil (bulk-1.4 g cm-3average; particle-2.5 to 2.7 g cm-3) (Brewer et al., 2009; Brewer and Levine, 2015). This lower density, especially bulk density, translates to a larger porosity and a potentially greater amount of pore pace that can allow water to infiltrate into the soil.% Solid Space = (bulkd density/particle density)*100% Porosity = 100 - (% Solid Space)Water infiltration is also affected by soil aggregates, and their stability after the addition of water. These water stable aggregates will be measured in this study for each plot with the method used in Marquez et al. (2004). This method involves the collection of a 100 g subsample of soil that is exposed to water and separated into four size fractions (>2mm, 0.25-2mm, 0.053-0.25mm, and <0.053mm). The aggregates from each size fraction will be dried at 65?C until constant weight and weighed to assess the total mass within each size range to then determine fractionation. More stable aggregates present within the soil will lead to greater infiltration rates assuming a greater amount of macropores between the aggregates that can assist with water and air movement within the soil. Though biochar may increase aggregation, a potential set back of biochar addition to soil is a slight increase in hydrophobicity (repellant of water). After the pyrolysis process of biochar, the organic substance starts out being slightly hydrophobic and can repel water until it ages. With time this hydrophobic property becomes less of a concern, but since this study focuses on the first two years after biochar application, soil hydrophobicity will need to be measured. The technique used to measure hydrophobicity of soil is simply measuring the amount of time it takes for a water droplet to infiltrate the soil with the Water Droplet Penetration Time method (Olorunfemi, 2014). All aforementioned soil physical properties will be measured four times during this study (before biochar application, directly after application, a year after application, and roughly two years after application). After measuring the soil physical properties that most impact water infiltration, the actual water infiltration rate will be measured via Cornell Sprinkle Infiltrometers. This technique uses an apparatus that simulates rainfall by sprinkling the ground and avoiding the ponding and sealing of soil macropores. It then allows the measure of water applied to the soil versus the water that runs off a specific soil surface area. The difference being the amount of water infiltrated into the soil over the time of the experiment (typically one hour). These infiltration rates will be measured roughly monthly and around precipitation events to assess infiltration rates under a variety of soil moisture conditions, measured with a Campbell Scientific HydroSense hand probe. The difference in infiltration between the tillage + biochar plot and the other treatments will allow for direct assessment of biochar's impact. The greater the infiltration rate, the less runoff expected during and after major runoff events.A potentially greater water volume infiltrating into the soil may affect the amount of nutrient leaching through the soil within the concentrated flow paths. To directly assess this change, resin lysimeters will be made and installed at a depth of 50 cm in each plot according to McIsaac et al. (2010), Behnke et al. (2012), Smith et al. (2013), and Davis et al. (2014), all of which have successfully used this method. In brief, positive and negative charged resin will be placed within PVC lysimeters that allow the movement of water through the apparatus while the ions are captured within the resin. This resin will collect all positive and negative charged nutrient ions for an entire year. After a year, the lysimeters will be dug up, resin rinsed with 2M KCl for ion extraction, and fresh resin lysimeters will be installed to collect the following year's worth of ion leaching. The 2M KCl extractant solution will be analyzed on a AQ300 SEAL Discrete Analyzer for ammonium, nitrate, and phosphate. Once again, a difference in ions leached between treatments will determine if biochar + tillage influences the leaching of ions.The results from these methods will be directly incorporated into peer-reviewed scientific publications and Penn State University (PSU) Extension programming lead by Dr. Groh. This will provide a two-pronged approach to reach most of our target audience. The planned Extension education will be focused on webinars, in-person events (pending COVID-19 in-person regulations), and written articles. The content will focus on introducing landowners as well as state agency personnel to biochar, its properties, and the results from this study. This programming will include a before and after content delivery survey which asks a series of knowledge questions in order assess changes in knowledge and comfort with the information. There will also be questions on the surveys that pertain to the "likelihood" of attendees applying biochar to their land based on their current knowledge of biochar. The difference in answers for before and after survey questionaries will result in an assessment of a potential change of knowledge and action.References: See Proposal Reference Section