Dr. Emma Matcham and Dr. Osler Ortez, Assistant Professors, Department of Horticulture and Crop Science, The Ohio State University
Factors affecting silage corn production include genetics, environment, and management practices (including nutrient management). Sulfur (S) is an essential nutrient in four amino acids, which are the basic components of protein molecules. This article will provide a basic overview of sulfur management, including the sources, rates, and timings that can impact corn silage yields and nutritive value.
Sulfur Overview
To determine if sulfur application might benefit your silage corn field, it is important to understand how much sulfur is necessary to grow a good crop of silage corn. We estimate that each ton of silage corn will remove about 1.1 lb of sulfur. In other words, around 27 lb of sulfur are removed per acre when yields are 24 ton/acre (TriState Fertilizer Recommendations, linked below).
Corn’s sulfur requirement can be met from a wide range of sources. Acid rain and other forms of atmospheric deposition of sulfur to soils were historically major contributors of sulfur to silage corn fields. However, atmospheric sulfur deposition has significantly declined since the 1990s due to changes in air quality regulations. More recent estimates are that Ohio fields receive around 5 to 6 lb of sulfur deposition per acre per year, sometimes more. Manure is another important sulfur source, and dairy manure typically contains 1.4 to 2.7 lb sulfur per 1000 gallons of liquid manure. Atmospheric deposition and a 5000 gallon per acre manure application will typically meet over half of the sulfur requirements for your silage corn crop (learn more about S rates in manure using ManureDB, linked below). Another source of sulfur is from organic matter mineralization and fertilizers. Many fertilizers like diammonium phosphate (DAP) contain around 2% sulfate (Camberato et al., 2023), and minor sources of sulfur entering your fields include ammonium sulfate (AMS) and other spray tank additives, many micronutrient fertilizers, and some fungicides.
When making sulfur application decisions, consider the 4Rs for nutrient management: Right rate, Right source, Right place, and Right time. For instance, the timing of sulfur application depends on nutrient source. Plants take up sulfur from the soil in the form of sulfate ions (SO4-1). Other forms of sulfur, such as elemental sulfur (S2) or organic sulfur (compounds with both sulfur and carbon atoms), must be converted to sulfate before they are plant available. The sulfur in DAP, AMS, and atmospheric deposition are usually in the sulfate form and can be immediately available for plant uptake. Sulfur utilization from these sources is higher when they are applied to a growing crop (with existing nutrient demand), since sulfate ions are highly mobile in the soil profile (like nitrogen) and can leach out of the root zone following heavy precipitation events. Manures can contain a mix of sulfate-sulfur and organic sulfur, so around half of the sulfur from manure is available in year 1 and around half will become available in future years after it gets mineralized. If you are looking to correct a S deficiency in the short-term during the growing season, products like gypsum (calcium sulfate), AMS, or other sulfate sources are more suitable.
Recent Sulfur Application Trial Results
Since 2013, 53 field trials with S applications in corn were conducted in Ohio, primarily with grain corn and primarily using spring-applied S in forms such as gypsum, AMS, or thiosulfate. Sulfur applications typically increased S concentrations in leaf tissue and grain, but that did not always translate to yield gains—only 44% of trials showed a positive response to S. These findings suggested that S deficiency is not a widespread problem in Ohio, but some corn fields can positively respond to S fertilization. Yield increases associated with S fertilization are more common on fields that have sandy soils with low organic matter and lack a history of manure application.
These results align with more recent studies. Four on-farm trials in 2022 and 2023 were conducted in Sandusky County to evaluate silage and grain corn’s response to S fertilizer across two contrasting soil types. Grain yields were maximized with 20 lb/acre of S, but only in the sandy soil. No statistical differences were found in the clay loam soil. Silage yields did not show statistical increases in yield associated with S fertilization. This work was taken one step further by evaluating the protein and amino acid (AA) profile response to S in both corn harvested for silage and for grain. Sulfur AA (cysteine and methionine) are part of the five limiting AA for animals (cysteine, methionine, lysine, threonine, and tryptophan), and these are often supplemented in dietary rations. The largest increases in protein content related to S application was observed on sandy soils, and even small changes in protein content can have large impacts on dairy ration costs.
Identifying Sulfur Deficiencies
Identifying S-deficient corn fields can help predict which fields may have increases in yield or protein content if S fertilizer is applied. The most prominent visual symptom of S deficiency is yellowing of leaves, especially younger leaves towards the top of the plant. Vegetative corn plants may have interveinal striping patterns instead of an even yellowing across entire leaves (Figure 1). Since similar symptoms can be caused by many different conditions, a tissue test is useful for identifying S deficiency. Generally, if corn leaves have 0.16-5.0% S content, they do not have a sulfur deficiency. More information about sufficiency ranges and tissue sample collection can be found in the Ohio Agronomy Guide and the Plant Tissue Test factsheet (both are linked below).
Figure 1. Sulfur deficient corn plant during early vegetative stages in Ohio, 2025. Source: Taylor Dill, The Ohio State University.
Further Reading
Learn more about manure nutrient content at ManureDB: http://manuredb.umn.edu/
Learn more about crop removal of nutrients in the TriState Fertilizer Recommendations: https://extensionpubs.osu.edu/tri-state-fertilizer-recommendations-for-corn-soybean-wheat-and-alfalfa-pdf/?searchid=0&search_query=974
Learn more about sulfate in fertilizers from Camberato et al. (2023): https://acsess.onlinelibrary.wiley.com/doi/full/10.1002/cft2.20248
Learn more about the Ohio-Michigan Silage Test, results available from 2005 to 2022: https://u.osu.edu/perf/archive/
Learn more about plant tissue testing in the Plant Tissue Test factsheet by Greg LaBarge: https://agcrops.osu.edu/sites/agcrops/files/publication-files/Tissue%20Testing.pdf
Learn more about corn management and nutrient sufficiency ranges in the Ohio Agronomy Guide: https://extensionpubs.osu.edu/ohio-agronomy-guide-16th-edition-pdf/