Agricultural blends are described. The agricultural blend includes synthetic gypsum having ammonium sulfate and a by-product of slag, the slag being selected from the group consisting of steel slag, stainless steel slag, alloy steel slag, carbon steel slag, and phosphate slag. Additionally or alternatively, the agricultural blend is delivered to soil, is a mineral soil amendment, is a soil conditioner, is a liming agent, is an additive to increase soil pH, is an additive to decrease metal toxicity, or a combination thereof.