Kenneth Michael Wacha

• Ph.D
• Hydrologist at United States Department of Agriculture

Soil organic matter is a small, but critical component of the soil. This article demonstrates the value of enhancing soil organic matter for increasing the functionality of soils. Earn 1 CEU in Soil & Water Management by reading this article and taking the quiz at www.certifiedcropadviser.org/education/classroom/classes/550 .

An improved modeling framework for capturing the effects of space and time-variant resistance to overland flow is developed for intensively managed landscapes. The framework builds on the WEPP model but it removes the limitations of the “equivalent” plane and time-invariant roughness assumption. The enhanced model therefore accounts for spatiotempo...

This study examines the rainfall-induced change in soil microroughness of a bare smooth soil surface in an agricultural field. The majority of soil microroughness studies have focused on surface roughness on the order of ∼ 5–50 mm and have reported a decay of soil surface roughness with rainfall. However, there is quantitative evidence from a few s...

Most available biogeochemical models focus within a soil profile and cannot adequately resolve contributions of the lighter size fractions of organic rich soils for Enrichment Ratio (ER) estimates, thereby causing unintended errors in Soil Organic Carbon (SOC) storage predictions. These models set ER as constant, usually equal to unity. The goal of...

To assess management impacts on the functionality of intensively managed agroecosystems, a modeling framework was developed with a bottom-up approach and spatially distributed, process-based models. The framework is equipped with dynamic, data-informed indicators and indices to illuminate the factors influencing sustainability. The proposed dynamic...

Organic cropping systems may potentially improve soil and environmental health relative to simplified conventional systems due to the use of extended crop rotations, perennial crops, and animal manure. However, few studies have evaluated the impacts of organic row crop systems on a suite of soil health indicators relative to conventional systems ac...

Agricultural systems evolve from the interactions of climate, crops, soils, management practices (e.g., tillage, cover crops, nutrient management), and economic risks and rewards. Alternatives to the corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] (C–S) cropping systems that dominate in the US Midwest may provide more sustainable use of resourc...

Agroecosystems comprise environmental, economic, and social components with complex interactions that affect systemwide performance. Attempts to describe or predict how agroecosystems respond to management must account for these interconnected components, so approaches that are limited to a single discipline cannot capture the complexities necessar...

This paper explores the growing interest in soil health, emphasizing its importance in optimizing crop production, ecosystem function, and biodiversity. Defined by the USDA-NRCS as the soil’s capacity to function as a vital ecosystem, soil health involves filtering contaminants, cycling nutrients, supporting infrastructure, and regulating water mov...

Understanding the complex processes occurring at the soil surface is challenging due to the intricate spatial variability and dynamic nature of these processes. An effective tool for elucidating these phenomena is three-dimensional (3D) reconstruction, which employs advanced imaging technologies to create a comprehensive representation of the soil...

Eastern red cedar (ERC, Juniperus virginiana L.) is a common tree species in agroforestry plantings and has great potential for bioenergy production due to physical and chemical characteristics of its biomass. The objective of this study was to assess the effects of ERC plantings on carbon (C) sequestration and selected soil quality parameters in e...

Massive quantities of energy flow through soils during a year. Emerging views indicate that when supplied with abundant energy, soil biology acts as a self‐organizing system as soil microbes forge their habitats into a porous, well‐aggregated structure with high functionality. The flow of energy to power these self‐organizing processes has not been...

A randomized complete block design experiment was performed in a growth chamber study to evaluate the short‐term impact of N amendment source on CO2 fluxes, aggregate stability, and aboveground plant biomass. Large intact soil cores (n = 6) were each segmented into three subplot treatment sources: (a) organic N (ORG‐N); (b) inorganic N (UAN‐32); an...

Raindrop impact derives from the kinetic energy of falling raindrops. Determining the kinetic energy of rainfall requires the size distribution and terminal velocity of raindrops, which necessitates complex instrumentation. To avoid this, empirical relations have been developed that relate rainfall intensity and the rate of kinetic energy, i.e., ti...

Corn (Zea mays L.) and soybean (Glycine max [L.] Merr.) production dominate Midwestern U.S. agriculture and impact the regional carbon and nitrogen cycles. Sustaining soil carbon is important for corn‐soybean production (CS); however, quantifying soil carbon changes requires long‐term field measurements and/or model simulations. In this study, chan...

Intensive row crop agriculture on loess mantled hillslopes in the upper Midwest, USA, accelerates soil erosion and the loss of organic matter by increasing soil aggregate breakdown, changing surface roughness patterns, and leaving soil exposed to rainfall and wind for much of the year. There is a knowledge gap, however, in relating how the dynamics...

This study aimed to better understand how tillage row orientation with respect to dominant flow‐pathway along hillslope impacts runoff and the transport of different sediment size fractions. Experimental plots were constructed in contour ridge till (CRT) and parallel ridge till (PRT) sites to monitor runoff and sediment fluxes. Particle size fracti...

In the past several decades, North and South Dakota have experienced increased agricultural expansion and crop rotation simplification, namely an increase in corn (Zeamays L.)– soybean [Glycine max (L.) Merr.] systems. This review investigates the nature and extent of those changes, the underlying causes, and the consequences they have on ecosystem...

In the past several decades, North and South Dakota have experienced increased agricultural expansion and crop rotation simplification, namely an increase in corn (Zea mays L.)– soybean [Glycine max (L.) Merr.] systems. This review investigates the nature and extent of those changes, the underlying causes, and the consequences they have on ecosyste...

Remote sensing offers the capability of observing an object without being in contact with the object. Throughout the recent history of agriculture, researchers have observed that different wavelengths of light are reflected differently by plant leaves or canopies and that these differences could be used to determine plant biophysical characteristic...

Agroecosystems are complex representations of the interactions occurring among multiple biological systems at the field and landscape scale. Models simulating these interactions across time and space are not very mature and expanding our current knowledge on crop, pest, and soils models provides a framework for how we use agroecological models to q...

The Midwestern US is dominated by corn (Zea mays L.) and soybean (Glycine max [L.] Merr.) production, and the carbon dynamics of this region are dominated by these production systems. An accurate regional estimate of gross primary production (GPP) is imperative and requires upscaling approaches. The aim of this study was to upscale corn and soybean...

Within agricultural soils, the active layer is by far the most dynamic in response to management. Tillage fragments the structure of the soil, breaking down aggregate size fractions and weakening soil aggregates and reducing their resilience to mechanical and hydrological forces. This can also dampen biological activity through alterations of the s...

Core Ideas Soil management affects carbon and water dynamics. Net ecosystem production was higher in reduced till systems. Ecosystem respiration was higher in tillage systems. Residue management most likely to affect net ecosystem production and ecosystem respiration. Corn [Zea mays L.] and soybean [Glycine max (L.) Merr.] are important US crops,...

Core Ideas IML‐CZO is structured to study system responses through event‐based monitoring. Management legacy has shaped critical zone processes. Management and weather affect landscape heterogeneity and surface–subsurface pathways. In intensively managed landscapes, interactions between surface (tillage) and subsurface (tile drainage) management w...

The role of tillage practices on soil aggregate properties has been mainly addressed at the pedon scale (i.e., soilscape scale) by treating landscape elements as disconnected. However, there is observed heterogeneity in aggregate properties along flowpaths, suggesting that landscape scale hydraulic processes are also important. This study examines...

Core Ideas Hydraulic sampling can affect bulk density measurements. The effect was greater for the subsoil. Correction measures had little or negative influence. Hydraulic sampling can induce artificial compaction or gaps in soil cores, which affects bulk density (BD) and carbon (C) stock estimation. We compared BD (0–120 cm) from hydraulic sample...

This study examines the rainfall induced change in soil microroughness of a bare soil surface in agricultural landscapes. The focus is on the quantification of roughness length under the action of rainfall for initial microroughness length scales of 2 mm or less, defined here as initial smooth surface conditions. These conditions have not been exte...

An enhanced revision of the Fox and Papanicolaou (hereafter referred to as "F-P") (2008a) Bayesian, Markov Chain Monte Carlo fingerprinting framework for estimating sediment source contributions and their associated uncertainties is presented. The F-P framework included two key deterministic parameters, α and β, that, respectively, reflected the sp...

Agricultural expansion and urbanization, coupled with climate change represent major threats to the sustainability of river ecosystems and infrastructure. In this study, we evaluated how subbasins with different dominant land covers within the 27.5 km2 Clear Creek, IA watershed affect key hydrologic indicators. Hydrologic output from two stream gag...

Changes in land cover can significantly affect the spatial and temporal heterogeneity of water-driven soil erosion and deposition in Intensively Managed Landscapes (IMLs), and hence the redistribution of soil organic carbon (SOC) along a hillslope. In IMLs, erosion and deposition are typically more prominent than in grassland and forested ecosystem...

Currently, biogeochemical models lack the ability to simulate accurately soil organic carbon (SOC) dynamics, especially in intensely managed landscapes (IMLs) located throughout much of the U.S. Midwest, as they do not account for lateral and downslope redistribution of soil and SOC. This limitation can increase the uncertainty in predicting SOC se...

Field measurements and numerical models are currently being used to estimate quantities of Total Belowground Carbon Allocation (TBCA) for three representative land uses, viz. corn, soybeans, and prairie bromegrass for CRP (Conservation Reserve Program) of an agricultural Iowa sub-watershed, located within the Clear Creek Watershed (CCW). Since it i...

Corn is a valuable commodity to our society that not only provides a vital food source, but can increase the sustainability of our agroecosystem. This includes ethanol/biodiesel production through biomass collection of stover and residue, monitoring storage of carbon in the soil for commodity exchange, and decreasing the erosion-induced spread of p...