Soil Health Indicators as Tools to Understand The Effects of Disturbance

Download or read book Soil Health Indicators as Tools to Understand The Effects of Disturbance written by Devyn Mc Pheeters and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soil health refers to a soil's ability to sustain biological life into the future while maintaining water and air quality. No-till agriculture has become a primary strategy to improve soil health in row-crop production in the United States. Growers who have adopted no-till practices are typically highly reluctant to use any type of tillage out of concern for its effects on the health of their soil. The two primary objectives of this thesis research were 1) to examine the effects on soil health of one-time inversion tillage in a six-year rotation including canola, corn, soy, cover crops and perennials and 2) to compare soil health effects of contrasting fertilization methods, involving either surface applications or incorporation using reduced disturbance, in a corn-soy rotation. These objectives were approached using four soil health indicators: total organic carbon, bulk density, labile carbon, and aggregate stability, to determine the impacts of different management strategies implemented at the Dairy Cropping Systems Experiment (DCSE) at the Penn State Agronomy Research Farm at Rock Springs, PA. This experiment had been initiated in 2010 as a full crop entry experiment, with all phases of the crop rotations planted every year in a randomized complete block design, replicated four times. The channery silt loam soil at this site was sampled in spring 2010 prior to the start of the experiment and in 2013, 2016, 2019, and 2021 at two depths: 0-5 and 5-15 cm for labile and total carbon and to 15 cm for aggregate stability. The research conducted under Objective One is described in Chapter Two of this thesis. The management system under study was a six-year crop rotation that included two approaches to terminating the perennial forage crop--termination by standard herbicides or by inversion tillage. The aim was to assess soil health effects of once-in-six-year tillage as a strategy for herbicide reduction (T1/6) when compared to no-tillage using standard herbicide treatment (NT). Although tillage initially reduced total soil organic and labile carbon, plots that were tilled showed similar soil health levels as the continuous no-till plots in all four indicators after two full years in perennial forage. Results from this analysis indicated that soil health can return to no-till levels despite a tillage event if rotated to perennial forage for sufficient years. The research for Objective Two is described in Chapter Three and involved a more traditional corn-soy rotation, which had been included in the Dairy Cropping Systems Experiment because it is common among grain crop growers. Soil health indicators were compared in soils subjected to four fertilizer application strategies: no-till with broadcast manure (NT-BM), chisel disk with broadcast manure (CD-BM), no-till with broadcast synthetic fertilizer (NT-SF), and no-till with injected manure (NT-IM). Despite the classification of chisel-disk as a type of conservation tillage, the CD-BM strategy had the highest expected potential to reduce soil health because of its increased level of disturbance. Investigating the impact of CD on soil health was the primary focus of this chapter. There was also some expectation that injected manure would reduce soil health due to disturbance associated with injection, which also motivated comparison of the three different no-till strategies. Soil total organic carbon, labile carbon, and aggregate stability were all reduced in the CD-BM strategy, though no effects due to tillage were observed at the 5-15 cm depth. Additionally, there were no differences between the effects of the three no-till strategies on soil health. Results from this analysis suggest that soil health is negatively impacted by chisel disking compared to no-till, but that manure injection does not appear to affect soil health. The concluding chapter of this thesis summarizes the results of both studies and provides recommendations for farmers and future research. Reducing tillage intensity is critical to improving soil health, though strategic timing of one-time tillage events may alleviate some of the herbicide requirement typically associated with no-till, particularly when these events are coupled with perennials in rotation. Chisel-disking may be a positive alternative to more intensive tillage practices, but it showed short-term negative impacts compared to no-till. Overall, this thesis supports the idea that reducing disturbance and increasing perenniality of systems is the key to long-term improvements to soil health.