Factors affecting soil nutrient availability and its impact on maize and soybean productivity

Harm Loman, Marcos

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https://hdl.handle.net/2142/124349 Copy

Description

Title

Factors affecting soil nutrient availability and its impact on maize and soybean productivity

Author(s)

Harm Loman, Marcos

Issue Date

2024-04-22

Director of Research (if dissertation) or Advisor (if thesis)

Below, Frederick E

Doctoral Committee Chair(s)

Below, Frederick E

Committee Member(s)

• Mulvaney, Richard L
• Margenot, Andrew
• Preza Fontes, Giovani

Department of Study

Crop Sciences

Discipline

Crop Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• soil fertility
• soil test
• maize
• soybean
• fertilizer
• fertilization

Abstract

Despite large advancements in yields of maize (Zea mays L.) and soybean [Glycine max (L.) Merr.] the past century, further increases are needed to meet the needs of a growing global population, while being able to preserve some of the remaining natural vegetation. Unfortunately, the economic principle of diminishing returns also applies to crop yields as additional gains become more challenging as yields get higher, and typically requires more intensive agronomic management and improved input utilization. Better fertilizer management is a critical aspect of this challenge, as mineral nutrient availability significantly impacts crop yields, and fertilizers are non-renewable resources that are frequently used inefficiently. Because the fertile soils of the Midwestern U.S. contain vast amounts of nutrients, soil testing is a common practice to assess nutrient availability and is especially important in soybean production, where reliance is often on existing soil nutrients rather than supplementary fertilization. Unlike soybeans, maize production typically requires fertilization with phosphorus (P) and potassium (K), which for convenience are often fall-applied. Secondary nutrients like S, or micronutrients like B, are also gaining attention due to their lower levels in soils and increasing reports of yield increases from their application, and co-granulated fertilizers offer ways to provide these nutrients along with the traditional P and K. However, some of the nutrients in these fertilizer formulations are soil-mobile (N, S, B), and can be lost, or fixed by the soil (P, K) during the five to six months between fertilization and crop establishment. Aligning nutrient availability with crop uptake is crucial to minimize losses and maximize both fertilizer use efficiency and crop yield. While selecting the appropriate combination of nutrients is critical in a fertilizer program, it does not guarantee increased nutrient availability, plant uptake, or yield gains because the chemistry of the soil plays a vital role in nutrient accessibility. Especially important is soil pH which is a key factor that farmers can manage, usually through the application of lime (calcium carbonate). Phosphorus availability is particularly pH-sensitive, and while lime-induced increases in soil pH could enhance P availability, there is a reluctance to co-apply lime and P fertilizers due to worry about forming unavailable calcium phosphates. What is not clear is whether changes in soil P availability from co-application with lime will more than offset fixation of fertilizer P in Illinois soils with the net result of better efficiency of fertilizer P use. Given these complexities in soil nutrient dynamics, the objectives of these studies were to determine how well soil test values explained yield differences of maize and soybean, and how fertilizer inputs and agronomic management strategies impacted nutrient availability, crop uptake, and ultimately, grain yield. This exploration was divided into four distinct research areas: Do soil test values predict yield of unfertilized soybean in Illinois? Preplant soil samples collected from 133 soybean trials across Illinois were analyzed for extractable nutrient concentrations and compared to unfertilized grain yields using Pearson correlation coefficients (r), principal factor analysis, and latent variable regression models. Soybean grain yield did not correlate strongly to any of the evaluated soil nutrients, however the strong association of planting date and yield (r = -0.56), led to dividing the data set into five planting date groups. Soil fertility levels resulted in strong correlations to yield for Late or Very-late planting groups, but not for the Early or Very-early groups. Regression analysis utilizing the latent variables from the factor analysis confirmed that soil fertility had a greater influence on grain yield for late-planted soybean than early-planted, and that these differences were associated with heavier seed weight, suggesting that late-planted soybeans may be more responsive to fertilization than early-planted soybeans. How does the source of fall-applied fertilizer affect the availability of mineral nutrients during the growing season and the productivity of maize? Nitrogen (N), P, K, sulfur (S), and boron (B) fertilizer treatments were applied in the fall using variations in fertilizer source (MAP, AMS, MES10, MOP+B, or Aspire) and the availability and location of these nutrients in the soil profile during the maize growing season were evaluated as were their impacts on grain yield. Most of the fall-applied N was not detected in the spring soil samples, while fall P fertilization increased topsoil-extractable P throughout the season, and both P sources increased grain yield over the untreated control (UTC). Conversely, K fertilization only increased extractable K in the top 0-15 cm at preplant and did not affect yield. Aspire increased soil extractable B over MOP+B at both sampling times, and at nearly all sampling depths, and increased grain yield over the UTC. The findings from this study highlight the differential availability of nutrients in the soil profile from fall fertilization and emphasize the importance of selecting appropriate fertilizer sources. Does the fall fertilizer source affect the growth and mineral nutrient uptake by young maize plants, and are these differences in tissue nutrient status correlated with grain yield? Various N, P, K, S, and B fertilizer sources (MAP, AMS, MES10, MOP+B, or Aspire) were applied in the fall to assess their impact on the accumulation (uptake) and concentration (status) of nutrients at the V8 growth stage of maize and to evaluate whether these values were correlated with early-season biomass, grain yield, or yield components. Fertilization with S increased both S concentration and accumulation, while B applications did not affect either the accumulation or concentration of B. All correlations between grain yield and V8 nutrient concentrations were weak, and the large variation in the values among the years indicates that nutrient concentrations were more environmentally driven than being true indicators of plant nutritional statuses. This study highlights the limitations of using metrics like critical nutrient concentration and sufficiency ranges during early maize growth stages as reliable indicators of plant nutritional status. Is co-applying phosphorus fertilizer and lime detrimental to soil phosphorus availability and the productivity of maize? To assess how co-application of P fertilizer and lime affects soil P availability and growth and productivity of maize, two experiments were conducted evaluating different rates and sources of fertilizer P and different rates of pelletized lime (PL) broadcast-applied in the fall. Experiment 1 evaluated a single rate of two P fertilizer sources (MAP or MES10), while Experiment 2 was a full factorial between three MAP (0, 45, and 90 kg P2O5 ha-1) and four PL rates (0, 225, 450, and 900 kg ha-1). In Experiment 1, adding lime to P fertilizer did not change seasonal soil P levels at any depth compared to fertilizer alone, but it increased vegetative growth and P uptake (both concentration and accumulation) when added to MAP (MAP+Lime) and yield when added to MES10. Conversely, in Experiment 2, lime additions resulted in both increases and decreases in topsoil P availability and grain yield, without any clear trends related to P or lime rates. Overall, these studies highlight that co-application of P fertilizers and lime in the fall in Illinois may not be as antagonistic as previously believed, and that there may be opportunities to use lime to increase the efficiency of P-fertilizer use.

Graduation Semester

2024-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2024 Loman, Marcos Harm

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