About

Daniel Kaiser is a professor in the Department of Soil, Water, and Climate at the University of Minnesota Twin Cities. His research focuses on crops and nutrient management, including the maintenance of fertilizer guidelines, evaluation of soil test methods for commodity crops, and nutrient cycling in cropping rotations with an emphasis on sulfur. He is also involved in the development and use of precision agriculture technologies in research and crop production. His work aims to improve fertilizer placement, particularly planter banded fertilizer use in corn, and to optimize nutrient management practices to enhance crop yields and environmental sustainability.

Research topics

• Metallurgy
• Materials science
• Agronomy
• Soil science
• Animal science
• Biology
• Composite material
• Chemistry
• Environmental science

Selected publications

• Soil Sulfur and Nitrogen Affect Wheat Flour Mixing Characteristics and Protein Features in Flour and Dough

  Cereal Chemistry · 2026-04-02

  articleOpen access

  ABSTRACT Background and Objectives Sulfur and nitrogen affect wheat yield and the protein content and quality. Hard red spring wheat (Albany cultivar) grown under six different soil nitrate application levels (0, 60, 120, 180, 240, and 300 lbs/acre) and two sulfur levels (0 or 20 lbs/acre) was used. Mixing characteristics of flours were determined using the Brabender Farinograph AT, while flour and dough were studied for their thiols and SDS cold protein solubility with or without dithiothreitol. Findings Nitrate‐only at 180 lbs/acre and nitrate and sulfur at 60:20 lbs/acre (3:1) flours had desirable mixing performance. Nitrate‐only fertilization did not affect cold protein extractability in dough and compacted flour proteins so that thiols could not be exposed even in the presence of chaotrope. Nitrate and sulfur application affected protein compactness but for 120:20 lbs/acre (A63) and 180:20 lbs/acre (A64) applications, while exposable thiols further decreased, decreasing as nitrate levels increased. Exposable thiols decreased in nitrate‐only doughs, with the no‐nitrate (A55), 120 lbs/acre (A57), and 180 lbs/acre (A58) showing greater decrease. Conclusions Sulfur singularly increased exposable thiols in dough and was not affected by presence of nitrate. Indeed, nitrate only or nitrate and sulfur together application seems to produce wheat flour that has a more ordered protein structure and improved association with solvent (water) when mixed into dough. Significance and Novelty: This has significance in fertilizer application in fields for wheat cultivation for specific end‐use.

  PublisherDOI

• Should starter fertilizer rate be adjusted by initial soil test P concentration?

  Agronomy Journal · 2025-09-01

  articleOpen access1st authorCorresponding

  Abstract Starter fertilizers containing phosphorus (P) are applied to increase corn ( Zea mays L.) early growth and ultimately grain yield. This study determined the rate of starter P needed to increase corn early plant growth and grain yield at differing starting soil test phosphorus (STP) concentrations with or without broadcast P application. Field trials were established at 10 site‐years in Minnesota using a split‐plot design. Main blocks consisted of 0 or 59 kg P ha −1 broadcast pre‐plant. Sub‐plots consisted of liquid starter fertilizer (10‐15‐0 N‐P‐K): 0, 29, 58, and 87 kg ha −1 applied on the corn seed. Analysis was conducted across sites after classifying each block per site (low, medium, high, and very high STP) according to University of Minnesota guidelines. Corn plant mass and P uptake at V5–V7 increased linearly as the rate of starter P regardless of where broadcast P was applied and initial STP concentration. Corn yield was increased by P when STP was in the low or medium STP classification, and application of starter P alone did not maximize grain yield in low P soils. The data indicate that 29 kg ha −1 of the starter applied in this study is sufficient to increase early plant growth and corn yield compared to broadcast P only when STP was medium or higher. Broadcast P is needed to maximize yield when STP was low, and varying starter rates more than 29 kg ha −1 will not result in a greater yield potential across sites versus broadcast P alone regardless of STP concentration.

  PublisherOA PDFDOI

• Factors affecting potassium retention in sandy soils

  Soil Science Society of America Journal · 2025-07-01 · 4 citations

  articleOpen accessSenior authorCorresponding

  Abstract Potassium (K) is a critical macronutrient for maximizing yields in agricultural crops. However, inconsistent responses to K fertilizer or soil test K levels have led researchers to question which soil properties influence K availability and cycling in soils. This study aimed to evaluate how K is retained in sandy soils. The specific objectives of this research were to (1) determine the influence of pH level on cation exchange capacity (CEC) and K sorption in coarse‐textured soils and (2) assess the impact of freeze–thaw cycling on K release across a range of agricultural soils. Soil was collected from 10 agricultural sites in Minnesota. Of these, four were used to evaluate K sorption and eight were used to assess K leaching following freeze–thaw weathering. Potassium sorption experiments revealed that sand‐textured soils exhibited limited K sorption as solution K increased, but a higher clay percent or CEC allowed for greater K sorption. The addition of calcium (Ca) in the sorption experiments resulted in K release for all sandy‐textured soils. In weathering studies, freeze–thaw cycling led to mixed effects on K leaching. Simulated irrigation water containing Ca and magnesium (Mg) significantly increased K leaching in comparison to deionized water. These studies indicate the need for tailored K recommendations in coarse‐textured, low‐CEC soils considering the limited K sorption capacity and influence of divalent cations.

  PublisherOA PDFDOI

• Changes in soil test phosphorus and soil cations following application of sewage sludge ash and other recycled phosphorus fertilizers

  Soil Science Society of America Journal · 2025-03-01

  articleOpen access

  Abstract Phosphorus (P) is essential to healthy plant development and is regularly applied in agronomic settings to ensure maximum crop yields. Sewage sludge incinerator ash (SSA) contains significant amounts of P and was investigated as a recycled P fertilizer in a 3‐year field study. Untreated SSA was applied at a range of agronomically appropriate rates based on water‐ and citrate‐soluble phosphate (WCSP) concentrations in a corn and soybean field study in Minnesota (Waukegan silt‐loam, pH 6.8) to determine the soil chemical effects of SSA amendment individually and compared with triple superphosphate (TSP), biosolids, and struvite. Concentrations of Olsen‐P and soil solution P ion fluxes from in‐situ plant root simulator probes increased with increasing rates of SSA and were significantly greater than control plots. Compared to the other P sources, SSA amendment increased soil test P at 50%–70% the increase observed with TSP amendment, while total P concentrations increased at 1.7–2.5 times the rate of increase with other P sources. This was due to the lower WCSP concentrations in SSA and the experimental choice to apply based on WCSP. Soil‐extractable concentrations and ion fluxes of copper (Cu) and zinc and total soil concentrations of Cu increased with SSA and biosolids application, indicating potential as a comprehensive nutrient source. Total concentrations of concerning elements including arsenic, cadmium, chromium, and lead did not increase above detection limits. Total mercury concentrations were statistically higher with SSA application compared with the control and other P sources, though the analytical sensitivity was significantly higher, and the increase was biologically marginal (an increase of 0.06 µg kg −1 P applied as SSA). Overall, soil chemical responses indicated that SSA increased concentrations of soil test P and some plant nutrients with minimal increases in concentrations of elements of concern.

  PublisherOA PDFDOI

• Corn response to sulfur fertilizer rate and source in Illinois

  Agronomy Journal · 2025-09-01

  articleOpen access

  Abstract Sulfur (S) is an essential nutrient for optimizing corn ( Zea mays L.) growth and yield. While S deficiency has increased in recent years, corn response to S fertilizer application remains challenging to predict owing to complex interactions among soil, crop, and weather conditions. Forty field trials were conducted between 2009 and 2011 over a range of soil types and environments to evaluate corn grain yield response to S fertilizer and assess the ability of soil and leaf S concentration to predict yield response to S fertilizer. Rate trials included two (0 and 34 kg S ha −1 ) or five rates (0 to 52 kg S ha −1 , in 13 kg ha −1 increments), whereas S sources were evaluated at 26 kg S ha −1 (ammonium sulfate [21‐0‐0‐24S], elemental S [0‐0‐0‐90S], gypsum [0‐0‐0‐21Ca‐17S], monoammonium phosphate [MAP] MAP‐10S [12‐40‐0‐10S], MAP‐10S+Zn [12‐40‐0‐10S‐1 Zn], and MAP‐15S [13‐33‐0‐15S]). Over the 3‐year study period, we found minimal yield response to S fertilizer application with an overall response rate of 5% (two of 40 trials). In addition, neither S fertilizer evaluated increased corn grain yield relative to no S at any site; however, elemental S significantly reduced yield in one of 18 sites. While S application generally increased soil and earleaf S concentration, this did not translate into yield increases; hence, the lack of relationship between relative yield and soil and earleaf S. Under the study's conditions, these results indicate that S fertilization is unlikely to increase corn yields, and standard diagnostic tests such as soil S and earleaf S concentration are unreliable in predicting yield response in the upper US Midwest. Future research should incorporate other organic and inorganic soil S fractions to improve understanding and prediction of crop response to S fertilization.

  PublisherOA PDFDOI

• Precipitation influences pre‐sidedress soil nitrate thresholds for corn production

  Soil Science Society of America Journal · 2025-05-01

  articleOpen access

  Abstract Minnesota is a leading corn ( Zea mays L.) producer in the United States, requiring substantial nitrogen (N) inputs for optimal yields. Using an in‐season critical soil nitrate (NO 3 − ‐N) concentration threshold to adjust fertilization rates can improve N management and reduce environmental impacts. This study assessed corn grain yield response to in‐season (i.e., V4–V6 corn development stage) soil NO 3 − ‐N concentration to establish a critical pre‐sidedress soil NO 3 − ‐N test (PSNT) under Minnesota conditions. Data included were obtained from 34 field experiments conducted from 2012 to 2019 across the major corn production regions of Minnesota. Relationships between PSNT and relative corn grain yield were analyzed using a quadratic‐plateau regression model. Across the entire dataset, a PSNT of 20 ± 2.5 mg NO 3 − ‐N kg −1 soil was the critical level to reach 97% of maximum corn grain yield. To increase suboptimum PSNT concentrations up to the critical threshold, application of 13.8 ± 2.4 kg N ha −1 is needed per 1 mg kg −1 increase in soil NO 3 − ‐N concentration based on pre‐/at planting N application, but validation is needed for actual sidedress applications. When precipitation was lower or greater than the 30‐year mean, the critical PSNT value was 21.5 or 17.4 mg kg⁻¹, respectively. Nonetheless, the 20 ± 2.5 mg NO 3 − ‐N kg −1 PSNT critical value is applicable across the state as limited model improvements were achieved when the data were segregated according to soil characteristics, location, corn material, and/or previous crop.

  PublisherOA PDFDOI

• Phosphorus management strategies for corn and soybean in the Upper US Midwest

  Agronomy Journal · 2025-03-01 · 2 citations

  articleOpen access1st authorCorresponding

  Abstract It has been questioned whether the sufficient phosphorus (P)management approach could maximize potential grain yield in today's agricultural systems. The objective of this research was to establish six long‐term experiments across Minnesota to test phosphorus (P) management strategies on soils with a defined long‐term P history. Four soil test phosphorus (STP) interpretation classes were established as whole plots (low, medium, high, and very high). Split‐plots within each STP class consisted of one split‐plot that did not receive P (−P), and the second split‐plot received a broadcast application of P fertilizer (+P) at the rate of 73 (low), 44 (medium), 15 (high), and 15 (very high) kg P ha −1 . Grain yield, grain P concentration, and grain P removal were determined during corn ( Zea mays L.) (2015 and 2016) and soybean [ Glycine max (L) Merr.] (2017) growing seasons. Grain yield was increased by P fertilizer at 7 of 18 site‐years. Grain yields were similar between fertilized STP plots at the very low and low for corn and very low for soybean compared to nonfertilized or fertilized high and very high STP plots. No yield increase was noted for fertilized high or very high plots. Grain P removal was increased by applied P at 14 of 18 site‐years at the low and medium STP classes with no increase for the high and very high P testing soils. Results from this research indicate no greater yield potential for soils built to high or very high STP classes versus adequately fertilizing low‐ or medium‐testing soils.

  PublisherOA PDFDOI

• Design of a European high-speed rail network and use of passenger demand forecasting to test European policy targets

  European Transport Research Review · 2025-04-11 · 4 citations

  articleOpen access

  Abstract High-speed rail (HSR) is regarded as an important element in the transformation of long-distance transportation towards a climate-friendly system with less road and air travel. The European Union adopted the Green Deal which sets specific targets to increase HSR travel demand in Europe. Although there is broad consensus that Europe’s HSR network needs to be improved, few systematic studies have yet proposed future European HSR networks with detailed travel times, stations, and service frequencies. This study designed an HSR network, dubbed the “Metropolitan Network”, which connects all metropolitan regions within the European Union. The network was tested with passenger demand forecasts, using a robust travel demand model based on supply and demand data across all modes of long-distance travel. The main finding of the study is that the recently revised TEN-T plans are not sufficient to meet the EU Green Deal targets, whereas the proposed “Metropolitan Network” will exceed these targets. However, substantial investments in HSR infrastructure and fleet capacity will be necessary.

  PublisherOA PDFDOI

• Models and sufficiency interpretation for estimating critical soil test values for the Fertilizer Recommendation Support Tool

  Soil Science Society of America Journal · 2024-06-08 · 14 citations

  articleOpen access

  Abstract Soil test correlation determines whether a soil test can be used to predict the need for fertilization based on the critical soil test value (CSTV). Our objectives were to compare the CSTV estimated from five combinations of correlation models and yield sufficiency interpretations and to select one method for soil test correlation performed with the Fertilizer Recommendation Support Tool (FRST). Four models were fit to three datasets with strong (Mehlich‐1 K), moderate (Mehlich‐3 K), or weak (Olsen P) correlations between soil test P or K and crop relative yield. We tested the arcsine‐log calibration curve (ALCC), exponential (EXP), linear plateau (LP), and quadratic plateau (QP) models. The CSTV was defined as 95% of the maximum predicted yield for the ALCC and EXP methods, the join point for LP, and both the join point and 95% of the maximum for the QP providing five CSTV predictions. The five CSTVs ranged from 46 to 66 mg kg −1 for the Mehlich‐1 K dataset, 115 to 165 mg kg −1 for the Mehlich‐3 K dataset, and 7 to 16 mg kg −1 for the Olsen P dataset. Ten pairwise comparisons showed the estimated CSTV was numerically and sometimes statistically influenced by the model and sufficiency level interpretation. Despite differences among CSTVs, the frequency of significant yield responses above and below the predicted CSTV was generally comparable among the methods, with false‐negative errors occurring at 0%–18% of sites for a given dataset. The QP model with a CSTV at 95% of the predicted maximum was selected as the modeling approach for FRST.

  PublisherOA PDFDOI

• Influence of potassium fertilization on alfalfa leaf and stem yield, forage quality, nutrient removal, and plant health

  Agrosystems Geosciences & Environment · 2023-02-01 · 15 citations

  articleOpen access

  Abstract Potassium (K) is an essential nutrient for plant growth. In K‐deficient soils, fertilization has been shown to increase herbage yield of alfalfa. The purpose of this study was to determine the effects of K fertilization on alfalfa leaf and stem yield, forage quality, nutrient removal, and plant health of a nonlodging experimental germplasm. Five alfalfa rotations had K fertilizer applied at three rates (0, 186, and 372 kg K ha −1 ) to soils already containing sufficient soil test K (223 mg kg −1 ). No overall yield differences were found related to K application rates, though K removal in total herbage increased by 30–58% with K fertilization, depending on alfalfa stand age. Leaf:stem ratios were not impacted by K fertilization. The concentrations of B, Ca, and Na decreased with K fertilization, while K concentrations increased, which may have resulted in B deficiencies. Leaf in vitro digestibility decreased significantly with the application of K. There was no benefit to crown rot disease resistance with increased K fertilization. This study supports that the addition of K to already sufficient soils does not lead to any additional economic benefits and may reduce productivity due to the reduction of B uptake and in vitro digestibility.

  PublisherOA PDFDOI

Frequent coauthors

• Emerson D. Nafziger

  10 shared

• Stefan Dietrich

  Karlsruhe Institute of Technology

  9 shared

• Fabián G. Fernández

  University of Minnesota

  9 shared

• Volker Schulze

  Karlsruhe Institute of Technology

  9 shared

• John A. Lamb

  8 shared

• John E. Sawyer

  Iowa State University

  7 shared

• Jeffrey A. Vetsch

  7 shared

• Carl J. Rosen

  7 shared

Labs

• Daniel Kaiser's LabPI