Modeling Soil Organic Carbon in Select Soils of Southeastern South Dakota

Soil organic matter (SOM) is composed of living biomass, dead plant and animal residues, and humus. Humus is a class of complex, organic molecules that are largely responsible for improving soil water holding capacity, nutrient mineralization, nutrient storage, and other critical soil functions. Soil organic carbon (SOC) accounts for approximately 60 percent of SOM and thus SOC is recognized as a strong indicator of soil health. Land use changes and intense cultivation of arable soils in the United States over the past century have led to large decreases in SOM. The objective of this research was to develop a multiple linear regression model to predict SOC levels in select southeastern South Dakota soils and the region. Conventional Till (CT), No-Till (NT), and Native Grass (NTVG) management systems were studied within South Dakota Major Land Resource Area 102B, 102C, and McCook County, South Dakota. It was hypothesized that NTVG treatments would have the highest SOC levels, followed by NT treatments, and CT treatments would have the least. Samples were analyzed for pH, electrical conductivity (EC), total nitrogen (TN), total carbon (TC), SOM, soil inorganic carbon (SIC), particle size, color, and water stable aggregates. Management was found to have a significant effect on soil pH, EC, TN, TC, and SOC compared to native conditions (

Crop Residue Management Challenges: A Special Issue Overview

The amount of crop residues that can be sustainability removed is highly variable and is a function of many factors including the soil, climatic, and plant characteristics. For example, leaving an insufficient amount of crop residue on the soil surface can be detrimental for soil quality, result in loss of soil organic matter (SOM), and increase soil erosion, whereas leaving excessive amounts can impair soil-seed contact, immobilize N, and/or keep soils cool and wet. This special issue evolved as an outcome of, “Crop Residues for Advanced Biofuels: Effects on Soil Carbon” workshop held in Sacramento, CA, in 2017. The goal of the special issue is to provide a forum for identifying knowledge gaps associated with crop residue management and to expand the discussion from a regional Midwestern U.S. to a global perspective. Several crop residue experiments as well as simulation modeling studies are included to examine effects of tillage, crop rotation, livestock grazing, and cover crops on greenhouse gas (GHG) emissions, crop yield, and soil or plant health. The special issue is divided into 4 sections that include (i) Estimating Crop Residue Removal and Modeling; (ii) Cultural Practice Impact on Soil Health; (iii) Residue Removal Impact on Soil and Plant Health; and (iv) Cultural Practice Impact on Carbon Storage and Greenhouse Gas Emissions

Winter Cereal Rye Cover Crop Decreased Nitrous Oxide Emissions During Early Spring

Despite differences between the cover crop growth and decomposition phases, few greenhouse gas (GHG) studies have separated these phases from each other. This study’s hypothesis was that a living cover crop reduces soil inorganic N concentrations and soil water, thereby reducing N2O emissions. We quantified the effects of a fall-planted living cereal rye (Secale cereale L.) cover crop (2017, 2018, 2019) on the following spring’s soil temperature, soil water, water-filled porosity (WFP), inorganic N, and GHG (N2O-N and CO2–C) emissions and compared these measurements to bare soil. The experimental design was a randomized complete block, where years were treated as blocks. Rye was fall planted in 2017, 2018, and 2019, but mostly emerged the following spring. The GHG emissions were near-continuously measured from early spring through June. Rye biomass was 1,049, 428, and 2,647 kg ha–1 in 2018, 2019, and 2020, respectively. Compared to the bare soil, rye reduced WFP in the surface 5 cm by 29, 15, and 26% in 2018, 2019, and 2020 and reduced soil NO3–N in surface 30 cm by 53% in 2019 (p = .04) and 65% in 2020 (p = .07), respectively. Rye changed the N2O and CO2 frequency emission signatures. It also reduced N2O emissions by 66% but did not influence CO2–C emissions during the period prior to corn (Zea mays L.) emergence (VE). After VE, rye and bare soils N2O emissions were similar. These results suggest that nitrous oxide (N2O-N) sampling protocols must account for early season impacts of the living cover

Northern Great Plains Saline Sodic Soil Development, Classification, Remediation, and Management.

Soil salinity and sodicity are issues of growing concern in the United States (U.S.) and globally. Knowledge gaps for glaciated, dryland salt-affected soils exist because much original salinity and sodicity research focused on irrigated systems. Land managers are being asked to produce food, feed, fiber, and fuel for an expanding global population. The number of land managers and crop advisors who are affected by these soils is increasing. Addressing salinity and sodicity knowledge gaps will be critical for their success. Salinity and sodicity have been impeding crop productivity since the advent of cultivation. Saline and sodic soils form via multiple natural and human-induced pathways. Parent materials that are inherently high in ion (salt) concentrations can, through dissolution of mineral materials, release ions to the soil-water solution. As rainfall patterns in certain regions, namely the North America Northern Great Plains (NGP), trend toward higher seasonal rainfall, water tables rise. Ions are then transported upward with the water table and then to the soil surface via capillary rise. This mechanism of salt accumulation is unique compared to irrigated systems where salts accumulate at the soil surface from applications of irrigation water that has a high electrical conductivity (EC). Fundamental differences between salt-accumulation in nonglaciated, irrigated systems and glaciated, dryland systems insinuate that management recommendations from irrigation-based systems may not be pertinent or applicable to the NGP. For this reason, there is great need for a comprehensive textbook on salinity and sodicity that encompasses the management challenges faced by land managers and crop advisors in all geographies. Additionally, further research in the NGP is needed to investigate potential salinity and sodicity reclamation strategies that are effective and that can realistically be implemented on working farms. Throughout this document, Chapter 1 addresses knowledge gaps in more detail. Chapter 2 discusses saline and sodic soil development across multiple geographies, how saline and sodic soils are measured and defined, and the classification system used in the U.S. for these soils. Chapter 3 discusses research findings and the effect of chemical amendments in combination with phytoremediation on soil health in NGP saline-sodic soils. Chapter 4 serves as a summary of the knowledge gaps, of key issues as identified by the research discussed herein, and of areas of future work to address the growing issue of saline and sodic soils

Supplimentary Information.docx

Data from : A Global Meta-analysis of Cover Crop Response on Soil Carbon Storage Within a Corn Production System</p