Impacts of Gypsum Application on Soil and Crop Performance in Ohio
Let's Talk Gypsum: A Source for Crop Nutrition in Ohio
Gypsum, a nursery for calcium (Ca) and sulfur (S), serves as a helpful companion for crop nutrition. Calcium is essential for soil balancing of base cations and acts as a soil amendment to improve soil health (Chen & Dick, 2011). But the question remains: when and how often should gypsum be applied to gain our desired soil and crop benefits? Here, we delve into recent studies on Ohio's cotton fields to shed light on the matter.
Gypsum: A Source of S for Crop Growth
Gypsum contains sulphate-bound S that readily supplies this essential nutrient to crops. Studies by Fleuridor et al. (2020) gave gypsum a thumbs-up but only in specific cases, with just one out of 25 experiments showing an increase in grain yield. The farms tested received organic fertilizers to cover overall crop nutrients, and the gypsum was applied within a week of crop emergence or to forage fields in early spring (see Table 1). A plausible explanation behind the slight increase in yield in one trial highlights that an additional S boost may not be likely when other fertilizers like manure are frequently used (Fleuridor et al., 2020).
Another study by Fleuridor et al. (2023) reported that only 4 out of 62 trials demonstrated a positive impact from S application - two in corn, two in soybeans, but none in wheat. Noticeably, the favorable sites received an application rate within the range of 20-180 lb of S per acre (see Table 1).
Chaganti et al. (2019) tested the influence of gypsum application on corn at two locations, applying 0, 0.5, or 1 ton/acre three distinct times - annually, biannually, or every four years. The study observed a yield increase only in one of the four years for one site but reported no interaction between N and gypsum application. Gypsum applied annually or biannually proved more advantageous than a one-time application of 2 tons per acre (see Table 1).
Building Organic Matter and Sulfur Levels in Ohio Soil
Less tillage is becoming increasingly common across Ohio cropland, leading to a gradual accumulation of organic matter over time. This organic matter contains sulfur, which gets released when mineralized, acting as a slow-release fertilizer that feeds sulfur to crops. In contrast, tillage can hasten the mineralization process, resulting in sulfate that often leaches before it can benefit the crops (nota bene: leaching refers to the downward movement of water and its dissolved substances). Therefore, as more conservation tillage is adopted in Ohio, there may be less need for sulfur fertilizers due to improved organic matter levels.
Gypsum: A Source of Ca for Soil Balancing
The balance of one nutrient in the soil can either synergistically or antagonistically affect the uptake of other nutrients. For instance, calcium (Ca) ions can exhibit an antagonistic effect with magnesium (Mg) ions. The presence of excess potassium (K) can impede the absorption of calcium and magnesium ions. Thus, maintaining an ideal ratio of base cations, known as soil balancing or basic cation saturation ratio, is crucial. Although gypsum does not offer significant boosts in crop yields (Chaganti & Culman, 2017), it can be utilized as a source of Ca for soil balancing.
Gypsum: Improving Soil Tilth, Soil Health, and Water Quality
While gypsum has been found beneficial for alleviating sodic soils, it also has been shown to benefit non-sodic soils. However, long-term studies are required to assess the impact of gypsum on soil health in Ohio. Short-term studies have shown noChanges in penetration resistance (a compaction indicator) and unsaturated hydraulic conductivity (a parameter of water movement in soil profile) (Fleuridor et al., 2021).
Gypsum application can have benefits for improving water quality. King et al. (2016) demonstrated a 41% reduction in dissolved reactive phosphorus (P) and a 40% reduction in total P loads in surface runoff after two gypsum applications of 1 ton/acre. This increase in the amount of calcium in soil and water can potentially reduce phosphorus solubility and decrease phosphorus loading in runoff.
In short, gypsum serves as a beneficial source of calcium and sulfur, but gains in yield responses can be erratic and rely on initial soil conditions. If your soil needs a boost in structure or subsoil acidity problems are present, gypsum can help. The Ohio Agronomy Guide and Tri-State Fertilizer Recommendations offer precise guidelines on gypsum use, timing, and expected yields based on local research. Consult these resources to customize your strategy for optimal gypsum benefits.
- Gypsum, a source of both calcium (Ca) and sulfur (S), serves not only as a helpful companion for crop nutrition but also as a slow-release fertilizer for sulfur due to organic matter accumulation in Ohio's soil through lesser tillage.
- Studies on Ohio's cotton fields suggest that gypsum application may boost sulfur (S) levels in crops, with favorable results observed in specific cases (Fleuridor et al., 2020). However, when organic fertilizers are frequently used, an additional S boost may not be likely.
- When it comes to calcium (Ca), gypsum can be utilized as a source for soil balancing, maintaining an ideal ratio of base cations, known as soil balancing or basic cation saturation ratio. While gypsum does not offer significant boosts in crop yields, it can help mitigate antagonistic effects with other nutrients like magnesium (Mg) and potassium (K).
- By improving soil tilth, soil health, and water quality, gypsum can potentially reduce phosphorus (P) solubility and loading in runoff, leading to better water quality (King et al., 2016). The Ohio Agronomy Guide and Tri-State Fertilizer Recommendations provide precise guidelines on gypsum use, timing, and expected yields based on local research to optimize benefits for health-and-wellness.
