Calcium Sulfate Fertilizer: A Versatile Nutritional Booster in Agricultural Production​

In the modern agricultural fertilization system, calcium sulfate fertilizer, with its unique compositional advantages and mild functional characteristics, has become an important fertilizer category that balances nutrient supply and soil improvement. This type of fertilizer, mainly composed of calcium sulfate, commonly exists in forms such as gypsum powder (made by grinding natural gypsum) and phosphogypsum (processed from chemical by - products). It can not only provide crops with two key nutrient elements, calcium and sulfur, but also improve the physical and chemical properties of soil, playing an irreplaceable role in various crop planting and soil remediation scenarios.​

From the perspective of nutrient supply, the core purpose of calcium sulfate fertilizer is to supplement calcium and sulfur for crops. As an essential secondary element for crop growth, calcium is a vital component of cell walls and can enhance the toughness and stress resistance of crop tissues. For crops with high calcium requirements, the application effect of calcium sulfate fertilizer is particularly significant. In tomato cultivation, applying calcium sulfate from the flowering stage to the fruit expansion stage can effectively prevent blossom - end rot, a physiological disease caused by insufficient calcium absorption. This not only makes the tomato skin thicker and more transport - resistant but also increases the fruit's sweetness and vitamin C content. In grape cultivation, calcium sulfate can be applied through root top - dressing or foliar spraying to reduce fruit cracking, promote uniform coloring of grape berries, and improve the rate of marketable fruits. Sulfur, on the other hand, is a key raw material for the synthesis of proteins and enzymes, and it participates in crop photosynthesis and nitrogen metabolism. For sulfur - loving crops such as rapeseed, garlic, and onions, calcium sulfate fertilizer can significantly increase crop yield and quality. For example, after applying it to rapeseed, the oil content of the seeds can be increased by 3% - 5%, and the lodging resistance of the plants is obviously enhanced.​

In the field of soil improvement, calcium sulfate fertilizer is a "natural regulator" for controlling saline - alkaline soil and acidic soil. For saline - alkaline soil (especially soda saline - alkaline soil), the calcium ions in calcium sulfate can exchange with the sodium ions on the surface of soil colloids, replacing the harmful sodium ions, which are then leached to the deep layer of the soil with irrigation water. This reduces the soil alkalinity (ESP value), improves the soil aggregate structure, and enhances the soil's air permeability, water - holding capacity, and fertilizer - retaining capacity. Practices in the arid and semi - arid areas of northwest China have shown that applying 500 - 800 kilograms of gypsum powder (the main form of calcium sulfate) per mu of saline - alkaline soil, combined with irrigation measures, can reduce the soil pH value from above 9.0 to below 8.5 after 2 - 3 consecutive years. The crop emergence rate can increase from less than 50% to more than 85%, and the per - mu yield of crops such as wheat and corn can increase by 100 - 200 kilograms. For acidic soil, the weakly alkaline nature of calcium sulfate (with a pH value of 7.0 - 8.0) can neutralize part of the soil acidity, supplement calcium to the soil at the same time, and alleviate the loss of elements such as calcium and magnesium caused by excessive acidity, creating a suitable pH environment for the growth of crop roots.​

Calcium sulfate fertilizer can also indirectly improve the utilization efficiency of other fertilizers by optimizing the soil environment. When applying nitrogen fertilizers (such as urea and ammonium bicarbonate), using them together with calcium sulfate can reduce the volatilization loss of nitrogen. Calcium ions can promote the activity of soil microorganisms, accelerate the conversion of nitrogen into ammonium nitrogen and nitrate nitrogen that can be absorbed by crops, and at the same time avoid the "fixation failure" caused by the excessive combination of ammonium ions with soil colloids. In the application of phosphorus and potassium fertilizers, calcium sulfate can reduce the activity of metal ions such as aluminum, iron, and manganese in the soil, prevent them from combining with phosphate radicals to form insoluble aluminum phosphate and iron phosphate, and thus improve the availability of phosphorus. Meanwhile, calcium ions can work synergistically with potassium ions to enhance the absorption capacity of crop roots for potassium and reduce the leaching loss of potassium in the soil. According to agricultural scientific research data, after applying calcium sulfate to the soil, the utilization rate of nitrogen fertilizer can be increased by 8% - 12%, and that of phosphorus fertilizer by 10% - 15%, significantly reducing fertilizer waste in agricultural production.​

In the cultivation of characteristic crops and organic agriculture, calcium sulfate fertilizer is an "ecological fertilizer" that meets the needs of green production. For berry crops such as strawberries and watermelons, calcium sulfate can not only provide calcium and sulfur nutrients to prevent physiological diseases of fruits but also, with its natural source (such as natural gypsum), meet the requirement of organic agriculture for "no chemical additives" in fertilizers, avoiding the potential impact of chemically synthesized fertilizers on soil and fruit quality. In the cultivation of edible fungi, calcium sulfate (commonly known as "gypsum") is an important auxiliary material for making culture media. Adding 1% - 2% gypsum powder can adjust the pH value of the culture medium, supplement calcium, promote the growth of mycelia and the development of fruiting bodies, and increase the yield and fruit body hardness of shiitake mushrooms and oyster mushrooms.​

It should be noted that the application of calcium sulfate fertilizer should be carried out scientifically in combination with soil types, crop needs, and fertilization plans. For sandy soil, it should be applied in small amounts and in batches to avoid nutrient loss caused by excessive one - time application. For heavy clay soil, it can be applied together with organic fertilizers to further enhance the soil improvement effect. For foliar spraying, calcium sulfate powder should be ground into fine particles (with a particle size of more than 100 meshes) and prepared into a 0.5% - 1% solution. It should be sprayed 2 - 3 times during the critical calcium - demanding periods of crops (such as the fruiting stage and expansion stage), with an interval of 7 - 10 days. With the in - depth development of the concept of green agricultural development, calcium sulfate fertilizer (especially recycled calcium sulfate fertilizer made from phosphogypsum) will play a more important role in resource recycling and soil ecological remediation, providing strong support for the sustainable development of agriculture.