While soybean is thought of as a highly competitive and resilient crop, early-season growth and development is critical to maximizing yields. Early planting is important, but it is early spring vigor and growth rates that determine yield potential. In other words, planting dates have little effect on soybean yields, but emergence dates and early season vigor do. Rainfall patterns have shifted significantly, making very heavy rainfall events more frequent, thus making drainage, tillage, and residue/cover crop research all the more critical.

Here we propose to utilize a wide range of contemporary crop management scenarios to examine many aspects of temperature, water, and nutrient availability and their effects on early planted soybean. We plan to utilize our existing Drainage x Tillage research site near Wells Minnesota to investigate the effects of residues on early planted soybean. We will also carefully examine the three-way interactions between residue quantity and quality, tillage, and drainage.
By including residue removal and cover crop treatments, we can investigate the effects of residue level on all aspects of both early-season and season-long soybean growth. We plan a first-of-a-kind experiment to evaluate effects of drainage, tillage, and residue on soil temperatures, moisture, and nutrient availability at the seed and in the rhizosphere from planting through harvest. Results from this multi-year trial will vastly improve the quality of recommendations regarding fall tillage, cover crop management, and planting management in both well-drained and poorly-drained soils.

Goal #1: Examine the primary effects of drainage, tillage, and corn residue or cover crops on spring soil conditions affecting planting, emergence, and vigor.
• Objective 1: Deploy soil monitoring to evaluate soil temperature and moisture profiles after spring thaw through planting, to examine soil temperatures and moisture at 2 and 4”
• Objective 2: Monitor soil moisture and temperature throughout the profile throughout the growing season.
• Objective 3: Evaluate yield and quality impacts of the primary treatments

Goal #2: Evaluate all two- and three-way interactions between drainage, tillage, and residue/cover crops on important soybean measures
• Objective 1: Examine all interactions on soybean yield
• Objective 2: Examine all interactions on soybean seed quality.

Goal #3: Examine the primary and interactive effects of drainage, tillage, and corn residue/cover crops on soil chemical and physical parameters.
• Objective 1: Examine nitrogen availability and mineralization profiles throughout the season.
• Objective 2: Examine soil carbon effects of these factors.
• Objective 3: Examine soil health parameters as affected by these primary treatments that may impact soybean growth, development, yield, and seed quality.

Goal #4: Complete a comprehensive physical, chemical, and biological analysis of the site to evaluate long-term effects of drainage and tillage on Minnesota soils productivity.
• Objective 1: Measure soil root penetration resistance, bulk density, and water infiltration.
• Objective 2: Measure total inorganic carbon and nitrogen and total organic carbon and nitrogen.
Objective 3: Measure biological parameters related to nitrogen availability: nitrogen mineralization potential and soil microbial community structure by soil phospholipid fatty acid analysis (PLFA).

This project will generate needed information to evaluate opportunities and challenges to soybean production under drained and undrained conditions when different tillage and crop residue management conditions are used. We will be able to better understand soil N availability and the effects of the various management variables being tested on soil health and productivity. Ultimately, this project will allow us to refine soybean management practices (or at least provide a first step) to tailor them to specific soil or cropping management conditions. Currently, very limited information is available on how the variables being considered in this study, which are commonly found throughout Minnesota, impact N availability and crop and soil productivity.

Further, Drs. Naeve and Fernandez have extensive experience in communicating research in effective ways to Extension clientele. Crop producers and other professionals benefit by having the latest research information in formats that are clear, concise, and actionable. Results from research outlined

in this proposal can be communicated to crop producers and ag professionals quickly and effectively by dedicated communications professionals as outlined in the proposal.

With the recent publication of results summarizing effects of drainage on optimal N rates on corn, there is tremendous interest in this site and the research we are conducting there. We plan to hold at least one field day in the summer of 2022, and will certainly be speaking of this work at various field days and events throughout 2022.

The study will be conducted in a long-term research site established on a farmer's field near Wells in south-central Minnesota.

Drainage conditions were established in 2011 with every plot having subsurface tile drains installed. The site was divided into eight blocks where four blocks were randomly assigned to be drained (control drainage structures fully open) and four were randomly assigned to be undrained (control drainage structures completely closed). Each of these blocks was subdivided to accommodate both corn and soybean crops that rotate every year. In 2017, three tillage treatments were imposed: 1) conventional,
2) strip-till, and 3) no-till. Starting in fall 2021 three levels of residue management were added: 1) corn residue removed, 2) cover crop planted in the fall and terminated in spring, and 3) traditional (residue left on the field). Within each of these levels there are five 10x30 ft plots that receive 0, 130, or 260 lbs N/ac during the corn phase and the following year during the soybean phase they receive no nitrogen. The N rates in corn were selected to establish soil N supply (0N) and calculate N use efficiency for the 130N [near the economic optimum N rate (EONR)] and 2x the EONR (260N). The remaining two plots receive 130 lbs N/ac during the corn phase

This treatment structure allows us to share one ‘control’ treatment (130 lbs N on corn) and no treatment on soybean. Therefore, this allows for two additional soybean treatments to compare with the control. We are primarily interested in treatments that interact with drainage, tillage, and residue. We plan to examine the effects of seed treatments and seeding rate across these multiple factors.



Corn Trt Soybean Trt Seed Treatment Population
130 lb 1 None 125k
130 lb 2 Yes 140k
130 lb 3 None 140k



Each of these 5 treatments is replicated within each of 3 residue, 3 tillage, and 2 drainage levels. Thus, the study has 360 10x30 ft plots in corn and 360 plots in soybean for a total of 720 plots. Below is depicted an outline of one block. Multiplied by two crops, two drainage levels, and four replications, there are 16 such blocks in this experiment.


Cover variable
A) Cover crop
B) Residue removed (only forcorn residue)
C) Standard practice (no residue management)

Tillage variable




Individual trts

Conventional Strip-till
No-till

Corn (lbs N/ac) Soy seed trt Soy pop




This proposal will only focus on the soybean plots and will only focus on some measurements. The proposal submitted to AFREC will focus on the corn plots and direct nitrogen effects on corn that are not part of this proposal. However, because all the treatments are followed by soybean and their residual effect will be measured in the soybean plots we will discuss the overall site management in this proposal.

Every fall after harvest, tillage and residue management treatments will be established. In the spring, the plots with cover crop will be chemically terminated. Corn plots will receive the N rate treatments before corn is planted. Next, the study will be planted using corn hybrids and soybean varieties and planting densities best suited to maximize productivity.

Blanket fertilizer treatments (other than nitrogen) will be made in the spring to balance any uneven fertility at the site from prior cycles of experiments. Soil monitoring sensors will be placed in all combinations of drainage and tillage to monitor spring warm up as soon as the frost leaves. Bulk corn will be planted across the site as early as possible utilizing the existing crop and tillage rotations.
Soybean plots will be planted with a small plot planter to establish defined soybean treatments within each drainage x tillage x residue block.

A thorough analysis of soil temperature and moisture at the seed depth will be initiated at planting and continue through emergence. Exact emergence dates and early season crop growth will be analyzed relative to soil and atmospheric data. Today, information about corn and soybean emergence relative to soil temperature and moisture profiles under different drainage and tillage conditions is woefully lacking. The treatments at this site provide an invaluable resource for generating this important resource.

Soil temperature and moisture profiles to 2’ depths will continue through the season. These data will be critically important for a better overall understanding of tillage and drainage effects on soil moisture levels. These data are critically important in connecting the dots between drainage, tillage, and yield effects. This will allow us to explain differences in yield responses to tillage and drainage across years.
Along with soil physical properties, we will examine nitrogen availability and mineralization profiles throughout the season. Corn and soybean plots will be maintained throughout the summer and plants will be harvested for yield and analyzed for seed quality at maturity.

As outlined in Goal 4, we will continue to fully characterize the site for soil physical, chemical, and biological chrematistics derived from the long-term effects of drainage and tillage on Minnesota soils productivity. Crop development and its ability to obtain water and nutrients can be impacted by how well the root system explores the soil volume. The three main variables proposed in this project (Drainage, Tillage, and Residue) have a direct effect on soil bulk density, water infiltration, and crop-root penetration and soil volume exploration. Similarly, soil carbon and nitrogen pools along with microbial communities are in a delicate balance that can be profoundly altered by our management. The long- term history of this study site provides a truly unique setting to investigate how the interaction of the main management variables already mentioned influence soil functions and ultimately soybean yield.
During the establishment phase in which residue management will be added to the long-term drainage and tillage variables, we will collect soil samples to establish a baseline of soil carbon and nitrogen pools and soil microbial community structure. This baseline is critically important to evaluate the impact of management over time. Soil carbon and nitrogen pools (organic, inorganic, and total) will be measured by chemical analysis and microbial communities by soil phospholipid fatty acid analysis (PLFA).

Update:
Soil moisture measurements
Because soil can vary greatly from place to place, extensive measurements and expensive study are often necessary. Four soil-plat-weather ground-based monitoring sensors (TEROS 12, Meter Group, Inc., Pullman, WA) are installed at four different depths (2”, 6”, 12” and 24”) considering the heterogeneity of the soil, spanning the entire root zone, in 32 different plots across the eight blocks. In order to map plant water stress, data from these sensors is sent back to the decision support system ZENTRA cloud (Meter Group, Inc., Pullman, WA). The measurements are taken on intervals of an hour, from early-season (May) through harvesting (~October).

Installation of the weather station and soil monitoring sensors.

Soil compaction
When soil particles are compressed, the amount of pore space between them is decreased, resulting in soil compaction. Soils that have been heavily compacted have fewer big holes, less total pore volume, and therefore a higher density. Water infiltration and drainage are both less rapid in compacted soil. This occurs because larger pores have a greater ability than smaller pores to transport water through the soil at a downward angle.

For the measurements of soil compaction, the use of a digital penetrometer was required. The measurements were performed at two different timings: right after planting, and at the soybean stage V2.

Plant Root Simulator (PRS®) probes
In agronomic, forestry, and ecological research, PRS® probes are an indispensable instrument because they provide a practical and affordable way to assess both geographical and temporal variations in nutrient supply rates for all soil ions at once.

The rate of nutrient supply for nitrate (NO3-N), ammonium (NH4-N), and phosphorus (P) accessible to plants was measured before planting and during the growing season using Plant Root Simulator (PRS)TM probes with ion-exchange membranes (Western Ag Innovations, Saskatoon, SK, Canada). In four plots at each block, two pairs of anion and cation PRSTM probes (total surface area = 17.5 cm2) were placed into the soil vertically for 10 cm for a burial period of three weeks before being pooled per plot for analysis. For full removal of any remaining soil after removal, the PRSTM probes are power washed in the lab using deionized water. After that, the probes are sent to the Western Ag lab for examination.

Root Sampling
At the stages V2 and R1, a linear foot-long sample of soybean was taken from the 2nd row of 24 different plots across the two drainage variables and the three tillage treatments in every repetition (8 repetitions total). Plants were washed and stored at +4 °C until processing. Roots were oven-dried at 60 °C for more than 48 h, and weighed to calculate dry weight biomass. Roots were scanned using the program RhizoVision Explorer v2.0.3 (Seethepalli and York, 2020) using algorithms described by Seethepalli et al. (2021).

Bulk density
Measurements of soil bulk density are frequently used as an input parameter for models that forecast soil dynamics. When aggregating soil data, such models frequently use bulk density measurements to account for horizon mass. For this unique measurement, the variables taken into account are drainage and tillage (24 plots total), at a depth of 6” and at field moisture content to oven-dried bulk density, at the stage R3.

Soil infiltration
Water on the soil surface enters the soil profile through a process known as infiltration. It relates to groundwater and overland flow, dictating the percentage of irrigation or rainwater that penetrates the soil and, consequently, influencing the quantity of runoff that causes future soil erosion. The soil infiltration method used was the single ring, which usually uses one ring of 30 cm in diameter and 20 cm in height. Two single measurements (both extremes of the middle rows) were performed per plot, with a total of 24 plots across the drainage and tillage variables, at the stage R3.

Multispectral Imaginary – Drone
The process of gathering data that provides insight into crop health and vegetation management is consolidated through the use of multispectral imagery. Agricultural drones with multispectral imaging camera sensors help farmers manage crops, soil, fertilizing, and irrigation more efficiently. One of the most often used vegetation indicators is the Normalized Difference Vegetation Index (NDVI), which measures the "greenness" or photosynthetic activity of plants. Based on the finding that various surfaces reflect various types of light differently, vegetation indexes were developed.

Particularly photosynthesis-active plants absorb the majority of the red light that strikes it while largely reflecting the near infrared light. In contrast to healthy vegetation, stressed or dying vegetation reflects more red light. Likewise, the reflection of light over non-vegetated surfaces is substantially more uniform.

During the 2022 summer season, drone flights weekly are performed at the site to keep up with the development of the canopy for both crops, corn and soybean.

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The long-term research project near Wells, MN, is being conducted to examine the effects of artificial soil drainage, soil tillage, and corn residue on soybean nutrient content, physiology measurements, and soil chemical and physical parameters. The study features eight blocks with corn-soybean rotation, distinguished by drained or undrained soil conditions and three tillage systems (conventional, strip-tillage, and no-tillage). Starting in the fall of 2021, three levels of residue management were implemented, involving the removal of corn residue, the planting and terminating a cover crop in the fall and spring, or the traditional approach of leaving residue on the field.

The goals and objectives of the study include monitoring soil temperature and moisture profiles, evaluating yield and quality impacts, examining interactions on soybean yield and seed quality, and analyzing nitrogen availability, soil carbon effects, and soil health parameters. The ultimate goal is to understand how these factors impact soybean growth, development, yield, and seed quality. After completing the study description, statistical graphics were compiled visually, representing the observed trends and patterns within the various treatment combinations. These graphics showcase the effects of drainage conditions, tillage practices, residue management, seed treatments, and seeding rates on both corn and soybean crops. They serve as valuable tools for analyzing and interpreting the research findings.

One of the study's findings pertains to the 2022 corn-growing season, considering different tillage treatments. It reveals no notable distinction between the two drainage conditions employed. However, it is worth noting that conventional tillage demonstrates a slightly higher yield at harvest compared to the no-tillage approach. Overall, the long-term research project provides valuable insights into the effects of various factors on soybean growth, development, yield, and seed quality using temporal crop management methods.

As mentioned above, the primary benefit of this work is to solve important soybean production challenges that do not always occur on flat, uniform, well-drained, and conventionally-tilled soils. This site and our multifaceted, unique treatment structure allow us the opportunity to look at a wide range of production system scenarios across a number of years to provide Minnesota farmers with answers to real-life questions that impact their bottom lines. Minnesota farmers have invested in this valuable research site for a number of years now, and the knowledge dividends are paying off.