Development of soil testing protocol in soils receiving shallow disc manure injection
Open Access
- Author:
- Meinen, Robert James
- Graduate Program:
- Soil Science
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- March 17, 2023
- Committee Members:
- Heather Karsten, Committee Member & Related Areas Repres
Peter Kleinman, Committee Member & Major Field Represnt
Robert Shannon, Committee Member & Related Areas Repres
Bradley Cardinale, Program Head/Chair
John Thomas Spargo, Chair & Dissertation Advisor
Douglas Brian Beegle, Dissertation Co-Advisor
John Spargo, Committee Member & Major Field Represnt
Douglas Beegle, Chair & Major Field Represnt - Keywords:
- soil sampling
soil nitrate
manure injection
manureshed - Abstract:
- Agricultural manure management can be problematic in watersheds such as the Chesapeake Bay when land-application introduces nitrogen and phosphorus into water systems. Shallow disc manure injection application technologies can conserve nitrogen and reduce the N:P ratio mismatch between manure nutrient supply and crop nutrient need. This is important at the field scale, but injection can also be a tool to assist with water quality improvement goals at a watershed scale. The lack of proper crediting of manure injection in the Chesapeake Bay Model is an obstacle to adoption since absence of model recognition means that agency funding and policies may not target adoption of the technology. Further, for adoption to occur, the technology must be recognized as a tool that provides agronomic, economic, and environmental benefit by decision makers as well as the service industries operating at the field level. Education of the professional manure application industry may impact adoption because individuals in the industry could use injection equipment across many acres and farms that they service. Contemporary crop producers need field-level decision management tools to support efficient nutrient utilization and crop production in soils where manure injection causes patterned soil nutrient heterogeneity. The work presented in the body of this dissertation address five objectives: 1) Use the manureshed concept to describe regional imbalances and different land area manure needs and application management scenarios. A case study of expansion of the swine and poultry industries in Pennsylvania from 2000 to 2020 demonstrated that social, animal welfare, and environmental forces influence whether new farms are located within current regions where manure nutrient production exceeds local crop nutrient needs. The swine industry was more likely to locate in regions where manure nutrients from the new farm were needed for local crops. Comparisons between typical manure application practices in Pennsylvania, Iowa, and North Carolina swine industries demonstrated differing land base needs in each state, indicating that nitrogen conservation achieved with manure injection technology adoption in Pennsylvania could assist with lower soil phosphorus accumulation and decrease nitrogen fertilizer use. 2) Supply nutrient conservation efficiency information for watershed modeling to promote manure injection through top-down implementation. The Chesapeake Bay Model Phase 6 Manure Injection and Incorporation Expert Panel was established to conduct an extensive literary review of studies that provided N and P conservation factors for times when manure was incorporated below the soil surface compared to surface application without incorporation. Coupling literature summation with professional judgement, the panel provided factors of reduction in manure ammonia emissions and N and P loading to waters of the Chesapeake Bay for injection, low disturbance incorporation, and high disturbance incorporation for both upland and coastal hydrogeomorphic regions of the watershed. Manure injection reduced ammonia volatilization loss by 85%, total P loading by 12%, and P loading by 36% in upland regions and 22% in coastal regions. The factors were implemented in the Phase 6 Chesapeake Bay Model. 3) Demonstrate that bottom-up education of professional manure handlers may be a tool to enhance technology adoption. A 2018 survey of individuals in the Pennsylvania Commercial Manure Hauler and Broker Certification Program demonstrated that those with greater contact with educational programming through certification rigor and continuing education scored higher on knowledge questions centered on program competencies, including questions concerning nutrient cycling. The average number of farms worked on annually by the 171 survey participants was 38.5 farms, indicating that increased education on items such as the benefits of manure injection, could influence business and field decisions that impact many acres and farms. 4) Develop a nitrate sampling protocol for Pre-sidedress Nitrate Test (PSNT) in soils with patterned nutrient heterogeneity caused by manure injection. A soil monolith sampler was used to remove 76 cm by 15 cm wide by 30+ cm deep blocks of soil oriented perpendicularly to injected dairy manure band orientation. This allowed intensive sampling of a uniform slice of soil across the injection band. Nitrate levels were determined for each core and modeling was utilized to determine the best practical field-level soil collection protocol. The recommended sampling technique attained five 30 cm deep soil cores, each spaced evenly and perpendicularly to the manure band at 15 cm apart. The sampling technique is to be repeated four times in a field, for a total of 20 collected samples that are composited to provide a single sample for laboratory analysis. The protocol does not require that manure band locations be known. 5) Encourage manure injection adoption through trials at cooperative farms. Side-by-side surface-applied and shallow disc injection manure plots were established at field scale prior to planting of corn at two cooperative dairy farms. In 2013 the Hess farm contained 4 plots of each manure treatment. In 2014 the Lehman farm contained 4 plots of each manure treatment as well as 3 unmanured control plots. Within each field plot, six 4.6 m by 9.1 m fertilizer ramp subplots were established through hand application of calculated amounts of ammonium sulfate fertilizer and were used to determine yield response curves. Manure injection placement was at 76 cm spacing. Soil PSNT sampling was conducted in subplots that received no additional fertilizer using traditional random sampling in surface manured and control plots and the 5-core equispaced sampling technique in injected manure plots. Results indicated that soil nitrate levels attained through random sampling in broadcast plots and equispaced sampling in injection plots did not differ in ability to predict N sidedress needs, however a small data set with large variability prevented conclusions that the sampling techniques were statistically similar.