Newell R. Kitchen

• United States Department of Agriculture

Plant N concentration (PNC) has been commonly used to guide farmers in assessing maize (Zea mays L.) N status and making in-season N fertilization decisions. However, PNC varies based on the development stage. Therefore, a relationship between biomass and N concentration is needed (i.e., critical N dilution curve; CNDC) to better understand when pl...

Plant N concentration (PNC) has been commonly used to guide farmers in assessing maize (Zea mays L.) N status and making in-season N fertilization decisions. However, PNC varies based on the development stage and therefore a relationship between biomass and N concentration is needed (i.e., critical N dilution curves; CNDC) to better understand when...

Various soil health indicators that measure a chemically defined fraction of nitrogen (N) or a process related to N cycling have been proposed to quantify the potential to supply N to crops, a key soil function. We evaluated five N indicators (total soil N, autoclavable citrate extractable N, water-extractable organic N, potentially mineralizable N...

Various soil health indicators that measure a chemically defined fraction of nitrogen (N) or a process related to N cycling have been proposed to quantify the potential to supply N to crops, a key soil function. We evaluated five N indicators (total soil N, autoclavable citrate extractable N, water‐extractable organic N, potentially mineralizable N...

Improving corn (Zea mays L.) nitrogen (N) rate fertilizer recommendation tools can improve farmers’ profits and mitigate N pollution. Numerous approaches have been tested to improve these tools, but to date improvements for predicting economically optimum N rate (EONR) have been modest. This work's objective was to use ensemble learning to improve...

Unmanned aerial vehicle (UAV) based remote sensing has been extensively used in precision agriculture applications , such as vegetation growth and health monitoring, yield estimation, and irrigation management. Conventional procedures for UAV data collection and processing require collecting highly overlapped images, stitching images to generate an...

The absence of clear empirical relationships between soil health and agronomic outcomes remains an obstacle to widespread adoption of soil health assessments in row crop systems. The objectives of this research were to (1) determine whether soil health indicators are connected to corn (Zea mays L.) productivity and (2) establish interpretive benchm...

Integration of reflectance sensors into commercial planter or tillage components have allowed for dense quantification of spatial soil variability. However, little is known about sensor performance and reproducibility. Therefore, research was conducted in Missouri, USA in 2019 to determine (i) how well sensors can estimate soil organic matter (OM)...

Maintaining a healthy soil microbiome is important for key soil functions and plant growth. However, little is known about temporal changes in soil microbial communities across different soils and nitrogen fertilization in production soils. The aim of this investigation was to determine soil bacterial and fungal baseline communities and seasonal ch...

Proximal sensing technologies can densely quantify soil organic matter (OM) variability using visible and near infrared (VNIR) reflectance spectroscopy. However, issues with global calibrations and varying water content can reduce accuracy. Therefore, research was conducted to determine OM prediction accuracy across soil volumetric water content (V...

Integrating soil health (SH) biological properties with soil fertility (SF) evaluations offers a unique opportunity to potentially refine fertilizer recommendations. The objectives of this research included: (a) evaluating current University of Missouri P and K fertilizer recommendations for corn (Zea mays L.) and (b) assess whether SH biological i...

Adjacent fields with contrasting histories present an opportunity to evaluate the legacy of management on soil health (SH) and grain productivity. In 2011, two fields transitioned to no‐till grain production. During the previous 25 yr, one was pasture (pasture‐to‐grain; PTG), whereas the other was annually tilled for grain cropping (long‐term grain...

The Missouri Soil and Water Conservation Program was initiated by the Department of Natural Resources (DNR) to address challenges related to soil and water degradation by examining soil health under real‐world management practices. Soil health data from 5,300 field sites enrolled in a DNR cost‐share program were analyzed for the effects of tillage...

Farmers, scientists, and other soil health stakeholders require interpretable indicators of soil hydraulic function. Determining which indicators to use has been difficult because of measurement disconformity, spatial and temporal variability, recently established treatments, and the effect of site characteristics on management practice differences...

Assessment of corn (Zea Mays L.) emergence uniformity is important to evaluate crop yield potential. Previous studies have shown the potential of unmanned aerial vehicle (UAV) imagery and deep learning (DL) models in estimating early stand count and plant spacing uniformity, but few have extended further to field-scale mapping. Additionally, estima...

Soil organic carbon (SOC) is closely tied to soil health. However, additional biological indicators may also provide insight about C dynamics and microbial activity. We used SOC and the other C indicators (potential C mineralization, permanganate oxidizable C, water extractable organic C, and ß-glucosidase enzyme activity) from the North American P...

For maize (Zea mays L.), nitrogen (N) fertilizer use is often summarized from field to global scales using average N use efficiency (NUE). But expressing NUE as averages is misleading because grain increase to added N diminishes near optimal yield. Thus, environmental risks increase as economic benefits decrease. Here, we use empirical datasets obt...

Soil organic carbon (SOC) is closely tied to soil health. However, additional biological indicators may also provide insight about C dynamics and microbial activity. We used SOC and the other C indicators (potential C mineralization, permanganate oxidizable C, water extractable organic C, and β-glucosidase enzyme activity) from the North American P...

Potential carbon mineralization (Cmin) is a commonly used indicator of soil health, with greater Cmin values interpreted as healthier soil. While Cmin values are typically greater in agricultural soils managed with minimal physical disturbance, the mechanisms driving the increases remain poorly understood. This study assessed bacterial and archaeal...

Accurate nitrogen (N) diagnosis early in the growing season across diverse soil, weather, and management conditions is challenging. Strategies using multi-source data are hypothesized to perform significantly better than approaches using crop sensing information alone. The objective of this study was to evaluate, across diverse environments, the po...

Maximum genetically possible crop growth and yield are inhibited by abiotic and or biotic stresses. Biotic stresses may include pests, insects or disease infestations whereas abiotic stress includes nutritional deficiencies. Sensors have been developed and are being developed to detect stresses and to assist in crop stress management. Decision supp...

Improving corn (Zeamays L.) N managementis pertinent to economic andenvironmental objectives. However, there are limited comprehensive data sources to develop and test N fertilizer decision aid tools across a wide geographic range of soil and weather scenarios. Therefore, a public‐industry partnership was formed to conduct standardized corn N rate...

Optimum plant stand density and uniformity is vital in order to maximize corn (Zea mays L.) yield potential. Assessment of stand density can occur shortly after seedlings begin to emerge, allowing for timely replant decisions. The conventional methods for evaluating an early plant stand rely on manual measurement and visual observation, which are t...

Improving corn (Zea mays L.) N fertilizer rate recommendation tools is necessary for improving farmers’ profits and minimizing N pollution. Research has repeatedly shown that weather and soil factors influence available N and crop N need. Adjusting available corn N recommendation tools with soil and weather measurements could improve farmers’ abili...

Highlights UAV imagery can be used to characterize newly-emerged corn plants. Size and shape features used in a random forest model are able to predict days after emergence within a 3-day window. Diameter and area were important size features for predicting DAE for the first, second, and third week of emergence. Abstract . Assessing corn (Zea mays...

Splitting the N application into two or more timings may improve corn (Zea mays L.) grain yield and N recovery relative to a single‐N application. A 49 site‐year study across eight U.S. Midwestern states compared the effect of an at‐planting (single‐N application) and two split‐N applications [45 (45+SD) or 90 kg N ha⁻¹ (90+SD) at planting with the...

Determining which corn nitrogen (N) fertilizer rate recommendation tools best predict crop N need would be valuable for maximizing profits and minimizing environmental consequences. To assist farmers with corn N rate decisions, multiple publicly available recommendation tools have been developed over the years. With the numerous tools available to...

Anaerobic potentially mineralizable nitrogen (PMN) combined with preplant nitrate test (PPNT) or pre‐sidedress nitrate test (PSNT) may improve corn (Zea mays L.) N management. Forty‐nine corn N response studies were conducted across the U.S. Midwest to evaluate the capacity of PPNT and PSNT to predict grain yield, N uptake, and economic optimal N r...

Soil microbes drive biological functions that mediate chemical and physical processes necessary for plants to sustain growth. Laboratory soil respiration has been proposed as one universal soil health indicator representing these functions, potentially informing crop and soil management decisions. Research is needed to test the premise that soil re...

Soil health indicator values vary based on parent material, native vegetation, and other soil forming factors; therefore, useful interpretations require consideration of inherent soil characteristics. Our objective was to evaluate the distribution of soil health indicators across soil and climate gradients throughout the state of Missouri through a...

The anaerobic potentially mineralizable N (PMN) test combined with the preplant (PPNT) and presidedress (PSNT) nitrate tests may improve corn (Zea mays L.) N fertilization predictions. Forty‐nine corn N response experiments (mostly corn following soybean [Glycine max (L.) Merr.]) were conducted in the U.S. Midwest from 2014–2016 to evaluate the abi...

Understanding the variables that affect the anaerobic potentially mineralizable N (PMNan) test should lead to a standard procedure of sample collection and incubation length, improving PMNan as a tool in corn (Zea mays L.) N management. We evaluated the effect of soil sample timing (preplant and V5 corn development stage [V5]), N fertilization (0 a...

Determining which corn (Zea mays L.) N fertilizer rate recommendation tools best predict crop N need would be valuable for maximizing profits and minimizing environmental consequences. Simultaneous comparisons of multiple tools across various environmental conditions have been limited. The objectives of this research were to evaluate the performanc...

Maize UAV Yield prediction Colour feature Modelling Variable-rate application Accurate crop yield estimation is important for agronomic and economic decision-making. This study evaluated the performance of imagery data acquired using a unmanned aerial vehicle (UAV)-based imaging system for estimating yield of maize (Zea mays L.) and the effects of...

Assessing corn (Zea Mays L.) emergence uniformity soon after planting is important for relating to grain production and for making replanting decisions. Unmanned aerial vehicle (UAV) imagery has been used for determining corn densities at vegetative growth stage 2 (V2) and later, but not as a tool for detecting emergence date. The objective of this...

Estimates of mineralizable N with the anaerobic potentially mineralizable N (PMNan) test could improve predictions of corn (Zea mays L.) economic optimal N rate (EONR). A study across eight US midwestern states was conducted to quantify the predictability of EONR for single and split N applications by PMNan. Treatment factors included different soi...

Nitrogen provided to crops through mineralization is an important factor in N management guidelines. Understanding of the interactive effects of soil and weather conditions on N mineralization needs to be improved. Relationships between anaerobic potentially mineralizable N (PMNan) and soil and weather conditions were evaluated under the contrastin...

Nitrogen (N) fertilizer recommendation tools could be improved for estimating corn (Zea mays L.) N needs by incorporating site-specific soil and weather information. However, an evaluation of analytical methods is needed to determine the success of incorporating this information. The objectives of this research were to evaluate statistical and mach...

Core Ideas A Machine Learning approach was innovatively used to predict corn EONR. Two features were created to approximate hydrological conditions for modeling EONR. Soil hydrology conditions were found essential in successful modeling in‐season EONR. Determination of in‐season N requirement for corn ( Zea mays L.) is challenging due to interacti...

Organic crop production is increasing with consumer demand, but research is needed on the best management practices that minimize greenhouse gas (GHG) emissions. This study was conducted in central Missouri from 2012 to 2014 using a 3-yr rotation, consisting of corn (Zea mays L.), cereal rye cover crop (Secale cereale L.), soybean (Glycine max L.),...

Innovations in precision agriculture (PA) have created opportunities to achieve a greater understanding of within-field variability. However, PA adoption has been hindered by uncertainty about field-specific performance and return on investment. Uncertainty could be better addressed by using innovative analyses that provide insights into variabilit...

On-farm assessments of Miscanthus × giganteus growth and nutrient export across a wide range of management and environmental conditions are needed to determine and model how this crop performs and where it should be placed on the landscape. Therefore, Miscanthus growth and nutrient concentration and nutrient export at harvest were monitored during...

Core Ideas Depth to claypan, landscape position, and cropping system influence soil fertility and nutrient buffering. Accounting for landscape‐variable depth to claypan could improve P and K management. Cover crops can help increase soil organic matter content. Cover crops may help reduce P requirements on claypan soils. Precise nutrient managemen...

This is a paper that compares the effect of single near planting nitrogen fertilizer applications and splitting up the nitrogen fertilizer application on soil nitrate-nitrogen content and corn grain yield

Assessment of soil health involves determining how well a soil is performing its biological, chemical, and physical functions relative to its inherent potential. Due to high cost, labor requirements, and soil disturbance, traditional laboratory analyses cannot provide high resolution soil health data. Therefore, sensor-based approaches are importan...

Research is lacking on the long-term impacts of field-scale precision agriculture practices on grain production. Following more than a decade (1993–2003) of yield and soil mapping and water quality assessment, a multi-faceted, ‘precision agriculture system’ (PAS) was implemented from 2004 to 2014 on a 36-ha field in central Missouri. The PAS target...

Core Ideas Topsoil depth influences P and K dynamics on claypan soils. Most P and K dynamics were inversely affected by depth to claypan. Accounting for depth to claypan could improve P and K fertilizer management. Precise P and K fertilizer management on claypan soils can be difficult due to variable topsoil thickness, or depth to claypan (DTC),...

Core Ideas The geographic scope, scale, and unique collaborative arrangement warrant documenting details of this work. The purpose of this article is to describe how the research was undertaken, reasons for the research methods, and the project's potential value. The project generated a valuable dataset across a wide array of weather and soils that...

Bulk apparent soil electrical conductivity (EC a ) sensors respond to multiple soil properties, including clay content, water content, and salt content (i.e. salinity). They provide a single sensor value for an entire soil profile down to a sensor-dependent measurement depth, weighted by a nonlinear response function. Because of this, it is general...

Switchgrass (Panicum virgatum L.) is an attractive bioenergy crop option for eroded portions of claypan landscapes where grain crop production is marginally profitable. Topsoil thickness above the claypan, or depth to claypan (DTC), can vary widely within fields, and little information exists on its impacts on N management of switchgrass. Therefore...

Core Ideas Topsoil thickness, or depth to claypan, mainly affected the biomass harvest of the integrated system. The integrated system had greater weed cover, less yield, more N, P, and K removal, and less profit than the biomass only system. The only advantage of the integrated system was enhanced yield resiliency in an extreme drought year. Swit...

Core Ideas Grain relative yield increased with depth to claypan, while switchgrass relative yield was unaffected. Grain yield was twice as temporally variable as switchgrass yield. Grain crops generally were more profitable than switchgrass across depth to claypan. Switchgrass has the capacity to reduce yield variability caused by depth to claypan....

Organic crop production is dependent on tillage for weed control, but because tillage can lead to decreased levels of soil organic carbon (SOC) alternative management needs to be explored. This study was conducted in Boone County, Missouri, in 2012 to 2014 to determine the effects of three organic production systems and four poultry compost rates o...

Core Ideas Miscanthus’s performance on eroded claypan soils was comparable to other more productive soil. Only 4 of 12 site‐year combinations required fertilizer N to maximize Miscanthus yield. Nitrogen priming had no benefit and the constant rate of 67 kg N ha ⁻¹ yr ⁻¹ was the lowest that maximized total yield. Relative leaf chlorophyll concentrat...

Conversion of annual grain crop systems to biofuel production systems can restore soil hydrologic function; however, information on these effects is limited. Hence, the objective of this study was to evaluate the influence of topsoil thickness on water infiltration in claypan soils for grain and switchgrass (Panicum virgatum L.) production systems....

This paper evaluates the use of the anaerobic potentially mineralizable nitrogen test as an index for nitrogen mineralization and its use to estimate N fertilizer needs of corn.

Core Ideas Growing a cellulosic bioenergy crop on degraded soils helps restore soil function. Switchgrass improved hydraulic properties of degraded claypan landscapes. Depth to claypan horizon was the main factor controlling these hydraulic properties. Loss of productive topsoil by erosion with time can reduce the productive capacity of soil and c...

Quantification and assessment of soil health involves determining how well a soil is performing its biological, chemical, and physical functions relative to its inherent potential. Due to high cost, labor requirements, and soil disturbance, traditional laboratory analyses cannot provide high resolution soil health data. Therefore, sensor-based appr...

Capturing the variability in soil‐landscape properties is a challenge for grain producers attempting to integrate spatial information into the decision process of precision agriculture (PA). Digital soil maps (DSMs) use traditional soil survey information and can be the basis for PA subfield delineation (e.g., management zones). However, public soi...

Sustainable grain crop production on vulnerable claypan soils requires improved knowledge of long-term impacts of conservation cropping systems (CS). Therefore, effects of CS and landscape positions (LP) on corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and wheat (Triticum aestivum L.) production were evaluated from 1991 to 2010 on a claypan...

Thousands of eroded-soil hectares in the U.S. Midwest have been planted to Miscanthus x giganteus as an industrial or bioenergy crop in recent years, but few studies on factors affecting crop establishment have been performed on these soils. The objective of this study was to quantify how both rhizome quality and depth of soil from the surface to t...

Kristen S. Veum is a research soil scientist, Rob-ert J. Kremer is a soil microbiologist (retired), Kenneth A. Sudduth is an agricultural engineer, Newell R. Kitchen and Robert N. Lerch are soil scientists, and Claire Baffaut is a research hydrol-ogist at the USDA Agricultural Research Service (ARS) Cropping Systems and Water Quality Unit in Columb...

Crop canopy reflectance sensing can be used to assess in-season nitrogen (N) health for automatic control of N fertilization, and several systems are commercially available. Because data comparing the performance of the different sensor designs is lacking, the objective of this research was to evaluate and compare commercial canopy reflectance sens...

Sensor-based approaches to assessment and quantification of soil quality are important to facilitate cost-effective, site-specific soil management. The objective of this research was to evaluate the ability of visible, near-infrared (VNIR) diffuse reflectance spectroscopy to estimate multiple soil quality indicators (SQIs) and Soil Management Asses...

Long-term monitoring data from agricultural watersheds are needed to determine if efforts to reduce nutrient transport from crop and pasture land have been effective. Goodwater Creek Experimental Watershed (GCEW), located in northeastern Missouri, is a high-runoff-potential watershed dominated by claypan soils. The objectives of this study were to:...

Nitrogen from agriculture is known to be a primary source of groundwater NO-N. Research was conducted in a northeastern Missouri watershed to assess the impact of cropping systems on NO-N for a loess and fractured glacial till aquifer underlying claypan soils. Three cropped fields with 10 yr of similar management were each instrumented with 20 to 2...

We document the 20-yr-long research effort to study the transport of N and P to surface and groundwater in Goodwater Creek Experimental Watershed. We also document related efforts in nearby claypan watersheds and watersheds with contrasting soil and hydrologic conditions across the northern Missouri-southern Iowa region. Details of the analytical m...

Many challenges currently facing agriculture require long-term data on landscape-scale hydrologic responses to weather, such as from the Goodwater Creek Experimental Watershed (GCEW), located in northeastern Missouri, USA. This watershed is prone to surface runoff despite shallow slopes, as a result of a significant smectitic clay layer 30 to 50 cm...

Purpose: Determining the spatial structure of data is important in understanding within-field variability for site-specific crop management. An understanding of the spatial structures present in the data may help illuminate interrelationships that are important in subsequent explanatory analyses, especially when site variables are correlated or are...

USDA-ARS National Laboratory for Agriculture and the Environment, Ames, IA The Salt River Basin in the Central Claypan Region of Missouri was selected as a benchmark watershed to assess long-term effects of conservation practices on soil quality as part of the Conservation Effects Assessment Project and the Long-Term Agroecosystem Research Network....

Switchgrass (Panicum virgatum L.) and miscanthus (Miscanthus × giganteus) have potential to meet a growing demand for renewable energy feedstock. Before producers will invest in planting these crops, they need credible estimations of the potential profits. The objective of this study was to examine profitability of growing these perennial bioenergy...

Year-to-year dynamics in weather affect both the timing of application and the potential hydrologic transport of pesticides. Further, the most commonly used pesticides dissipate in the environment during the growing season. Interactions among these factors – hydrology, timing of application and dissipation kinetics – hinder the detection of tempora...

Agricultural land has been recognized as a significant source of greenhouse gas (GHG) emissions, however GHG release from soils varies as crop production strategies vary. This study was conducted to determine the effects of tillage, cover crop, and compost rate on the soil release of two GHG, nitrous oxide and carbon dioxide, under an organic soybe...

Evaluation of site-specific crop management has often considered only a single management practice at a time. Research is needed that simultaneously considers economic and environmental objectives in crop production. From over a decade (1993-2003) of yield and soil mapping and water quality assessment, a multi-faceted, “precision agriculture system...

Apparent soil electrical conductivity (ECa), a widely used proximal soil sensing technology, is related to several important soil properties, including salinity, clay content, and bulk density. Particularly in layered soils, interpretation of ECa variations would be enhanced with better calibrations to depth-wise variations in these soil properties...

A horizontally operating on-the-go soil strength profile sensor (SSPS) was previously developed so that the within-field spatial variability in soil strength could be measured at five evenly spaced depths down to 50 cm. Force divided by the base area of the sensing tip of the SSPS was defined as a prismatic soil strength index (PSSI, MPa), similar...

Nitrous oxide (N₂O) is often the largest single component of the greenhouse-gas budget of individual cropping systems, as well as for the US agricultural sector as a whole. Here, we highlight the factors that make mitigating N₂O emissions from fertilized agroecosystems such a difficult challenge, and discuss how these factors limit the effectivenes...

Soil properties and weather conditions are known to affect soil N availability and plant N uptake; however, studies examining N response as affected by soil and weather sometimes give conflicting results. Meta-analysis is a statistical method for estimating treatment effects in a series of experiments to explain the sources of heterogeneity. In thi...

Targeting critical management areas (CMAs) within cropped fields is essential to maximize production while implementing alternative management practices that will minimize impacts on water quality. The objective of this study was to develop physically based indices to identify CMAs in a 35 ha (88 ac) field characterized by a restrictive clay layer...

Purpose: This study was performed to develop a simple, disposable thin-film optical nitrate sensor. Methods: The sensor was fabricated by applying a nitrate-selective polymer membrane on the surface of a thin polyester film. The membrane was composed of polyvinylchloride (PVC), plasticizer, fluorescent dye, and nitrate-selective ionophore. Fluoresc...

The ability of hyperspectral image (HSI) data to provide estimates of soil electrical conductivity (ECa) and soil fertility levels without requiring extensive field data collection was investigated. The relationships between HSI spectral reflectance signatures and soil properties were analyzed to evaluate the usefulness of HSI for quantifying withi...

The Central Claypan region is an important agricultural production contributor in the U.S. Midwest. Because of the tendency for grain yield fluctuations caused by water stress, however, claypan soils may have potential for conversion from grain to grass production in support of biomass energy markets and conservation programs. This study examined t...