Recipient Organization
KENTUCKY STATE UNIVERSITY
(N/A)
FRANKFORT,KY 40601
Performing Department
Agriculture & Environmental Science
Non Technical Summary
Tillage and cropping systems that are tailored to increase input of carbon in soils also have the added benefit of improving soil health. The corresponding agronomic and ecosystem benefits are also substantial. Currently, several promising and effective crop and soil management practices that increase inputs of soil organic carbon (SOC) in agricultural soils, such as reduced tillage, soil amendments, cover cropping, and crop rotation, are increasingly being used in many regions across the United States. Additionally, these practices could increase the robustness and resilience of farming systems through the provision of ecosystem services, including enhancing soil aeration, maintaining soil structure and stability, facilitating nutrient cycling, and pollutant filtering. Despite their benefits to soil health, the extent to which U.S. farmers adopt these practices is still limited (e.g., cover crops are used on only <5% of the total croplands in the U.S.). To facilitate broader adoption, management for SOC should use multiple practices and approaches to increase SOC and keep soils healthy. Long-term research on the potential impacts of soil tillage and cropping practices on SOC and other soil health attributes is critical if the positive soil and environmental effects of soil conservation practices are to be achieved. A key step towards making soils sustainable is evaluating a suite of cropping and soil management interventions not only on the basis of narrow ranges of profitability, but also by the multiple ecosystem services rendered, including benefits associated with SOC sequestration and its long-term stability. The overall objective of this project is to assess the impacts of tillage, cover crops, and biochar amendments on SOC and on select physical and chemical soil properties. Specifically, for this study, we will compare the long-term impacts of two tillage treatments (conventional and no-tillage) in conjunction with the use of biochar on soil organic matter (SOM) and other soil attributes (bulk density, infiltration, hydraulic conductivity, water retention, and nutrient availability). We will explore the links between tillage and use of biochar as a soil amendment, particularly the ways in which tillage affects the long-term use of biochar in increasing SOC and soil C storage. In the long term, understanding these linkages will provide farmers new insights and allow them to make informed decisions as to how to adopt and incorporate adaptive soil conservation strategies that enhance both soil quality and crop yield.
Animal Health Component
90%
Research Effort Categories
Basic
10%
Applied
90%
Developmental
(N/A)
Goals / Objectives
The primary objective of the study is to compare how SOC and other soil physical properties are affected under two tillage systems (no-till/cover crop vs moldboard plowing) and in soil amended with biochar. Three treatments (no-till/cover crop, permanent pasture, and mold-plowed soils) will be compared for SOC and a select set of soil health indicators: soil bulk density, pH, CO2 efflux, soil temperature, soil moisture, and soil heat flux. Specifically, the project has three objectives:To examine the benefits of innovative soil conservation activities, including reduced tillage, cover crops, crop rotation, and biochar, on SOC and other soil health indicators under Kentucky's climate and soil conditions;To examine the link between biochar, SOC, and other soil physical properties; andTo evaluate and compare yields in relation to SOC levels influenced by tillage, cover cropping, and the use of biochar.Key questions include:How do changing agricultural practices, including tillage, cover cropping, and biochar, affect SOC and soil health and to what extent do these management practices affect crop yield?What are the relative performance and long-term impacts of biochar on soil health and SOC under tilled and non-tilled soils?
Project Methods
Study SiteThe study site, the Harold R. Benson Research and Demonstration Farm, is 15 miles south of the main campus of Kentucky State University, in the city of Frankfort, Kentucky.Experimental design and statistical analysis The experimental site comprises four complete blocks (31.5 m x 52.5 m), separated by 3.5-m border zones. We will use a split-plot design consisting of two main plots comprised of two tillage types, replicated in four complete blocks (raw wise). The subplots are four soil amendments treatments (cover crop, biochar, cover crop + biochar, and control) replicated four times for a total of 32 experimental units with each subplot area 7 m wide x 14 m long. The biochar used in this study will be provided from a commercial producer (Wakefield Agricultural Carbon; Columbia, MO). The company reports this biochar is produced from southern yellow pine, a soft wood feedstock with the following nutrient analysis: bulk density 0.482 g/cm3, 95.12% total organic matter (on mass basis) composed of 88.01% total organic carbon (87.17%), a small fraction (0.34%) of inorganic carbon, and 2.2% ash. The cover crops plots will be seeded with a mix of grasses and legumes (cereal rye, Austrian winter pea, and crimson clover) at NRCS-recommended planting rates. Treatment effects of the corresponding whole-plot, sub-plot, and interaction (whole-plot x sub-plot) factors will be will be evaluated using one-way ANOVA and LSD will be used to separate means (α = 0.05; SPSS version 22.0; SPSS, 2016).Objective 1: To examine the benefits of innovative soil conservation activities, including reduced tillage, cover crops, crop rotation, and biochar, on SOC and other soil health indicators under Kentucky climate and soil conditions.Soil Organic Matter (SOM) functional poolsPermanganate (KMnO4) test for estimating labile C The permanganate oxidizable carbon (POXC) test, a chemical method developed by Weil et al. (2003), will be used to estimate labile C.Total soil carbon and nitrogen determinationTo assess the effect of each treatment, soil C content at four soil depths (0-5, 5-15, 30-50, and 50-75 cm) will be sampled at three sites once a year after the main cropping season. Soil samples from each layer will be segregated into three classes: 250-1500, 50-250, and <50 μm (finest), representing three fraction categories. Soil samples will be sent to the University of Kentucky Soil laboratory for analysis for P, K, Ca, Mg, Mn, Fe, and Zn.Total soil enzyme activities (spectrophotometric determination)Spectrophotometric determination of the hydrolysis of fluorescein diacetate quantification of total soil enzyme activity will be performed by measuring the intensity of color formation using a spectrophotometer (Chakrabarti et al., 2005; Antonious, 2013b).Soil carbon respiration (soil CO2 efflux)To assess the long-term effect of tillage, cover cropping, biochar, and rotational practices on soil respiration, measuring the rate at which CO2 (µmol CO2 m-2 s-1) gas is emitted is critical. Specifically, differences in the rate of the SOM decomposition will be evaluated across treatments and over time via an automated soil respiration chamber (LI-8100, Lincoln, Nebraska) with LI-8150 multiplexer will be installed to measure soil CO2 efflux (μmol CO2 m-2 s-1) over time. The CO2/H2O analyzer provides a series of chamber CO2 concentrations at predetermined time intervals along with soil temperature and soil moisture.Objective 2: To examine the link between biochar, SOC and other soil physical propertiesAggregate stabilityAggregate stability will be determined on all surface and subsurface soil samples taken from each plot using the wet sieve technique (Kemper and Rosenau, 1986).Soil pH will be measured on all samples in both water and 1M KCl at a 1:2.5 soil to solution ratio. Samples will be shaken for 30 min on a reciprocating horizontal shaker, left to sit for another 30 min, and then pH will be measured.Cation exchange capacity (CEC)Data on the exchangeable basic cations (Ca, Mg, Na, and K) will be obtained from the UK soil lab. Since soil in this region is slightly acidic (pH <7.2), the Mehlich 3 method will be followed as described by Sikora and Moore (2014).Bulk density (BD)Field bulk density will be determined using the clod method (volume displacement) according to Grossman and Reinsch (2002). For consistency, the timing for the sampling (using a bulk density sampler) for BD determination will take place just before the harvest of main crop is completed. Samples collected at depths of 5-10 cm, 10-20 cm, and 20-40 cm will be assessed for BD.Objective 3: To evaluate and compare yields in relation to SOC levels influenced by tillage, cover cropping, and use of biochar Plant biomass Above-ground biomass (kg m-2) of the main crops will be taken at a regular intervals, from early establishment to maturity and during the flowering stage. Above-ground plant biomass is determined from the standing biomass (leaf, stem) removed from a 1-m2 quadrant at each location, immediately bagged, and transported to a nearby lab for determination of leaf area and morphological assessments. Dry weights of roots and the above-ground biomass (separated into roots leaf, stem and grain) are determined after plant materials are dried in a forced-air walk-in oven (80°C for 48 h).Crop physiology assessmentDuring the main growing season, leaf photosynthesis (A, μmol CO2 m-2s-1) will be measured using a portable open photosynthesis system (Li-400: LI-COR Inc., Lincoln, NE) to determine effects each of soil management treatment on plant physiological performance. Light-saturated photosynthetic rates (Amax) will also be measured on a subset of plants (n=6) at each site.Crop C and N analysis Crop residues play an important part in the SOM cycle. Above- and below-ground residues contribute directly to the SOM as it is their decomposition that forms SOM (Haynes, 2005). Oven-dried plant samples will be finely milled and the C and N content analyzed using a dry combustion method. This measurement is intended to examine the quality of the crop residues and the rate at which they degrade as well as the amount of C and N contributed to the soil due to cover cropping or plant material left from the main crops.