Generally, we only know that gypsum powder is used in construction industry, but seldom know that gypsum powder plays a very important role in agricultural production. The original application scope of gypsum powder is so wide. Hongtai gypsum introduces three major applications of gypsum powder in agriculture.

　　1、改良土壤，调节ph值，适宜盐碱地、红壤改良。

　　1. Improve the soil, adjust the pH value, suitable for the improvement of saline-alkali land and red soil.

　　2. 食用菌可作为钙、硫复合矿质肥料，调节培养基的ph值。

　　2. Edible fungi can be used as calcium and sulfur compound mineral fertilizer to regulate the pH value of the medium.

　　3.用于畜禽饲料的复合矿物饲料添加剂。

　　3. Compound mineral feed additives for livestock and poultry feed.

　　在生产中，由于石膏模具固有的易变性，使得石膏模具的质量难以稳定控制。这种变化的一个方面是膏体水比和膏体浓度对石膏模型性能的影响。一般来说，膏体水比小，模型孔隙率高，强度低，使用寿命短。膏体水比大，孔隙率低，强度高，使用寿命长。膏水比变化的影响与石膏粉的老化时间有关，尤其是新烧石膏粉与熟化石膏粉的差异。新烧石膏粉未发生变质、均质，温度高，表面活性强，混水能力大。立即用于成型，模型表面会形成许多气泡，整体强度较低。一般情况下，新炒制石膏粉需存放两周后再敷。

　　In production, because of the inherent variability of gypsum mould, the quality of gypsum mould is difficult to control steadily. One aspect of this change is the influence of water ratio and concentration of gypsum on the performance of gypsum model. Generally speaking, the paste has small water ratio, high porosity, low strength and short service life. The paste has high water ratio, low porosity, high strength and long service life. The change of gypsum water ratio is related to the aging time of gypsum powder, especially the difference between newly fired gypsum powder and mature gypsum powder. The newly fired gypsum powder has no deterioration, homogenization, high temperature, strong surface activity and high water mixing capacity. When used immediately, many bubbles will be formed on the surface of the model, and the overall strength is low. Generally, the newly fried gypsum powder needs to be stored for two weeks before it is applied.

　　国外学者的研究结果表明，石膏粉的含水率和流变特性随贮存时间的变化而变化，这是由于空气中石膏的老化过程造成的。该工艺可分为两个阶段:一是可溶性无水石膏(无水石膏)快速水化形成半水石膏;半水石膏吸收水分的速度非常慢，使晶体转化完成，混合水量逐渐下降。在空气相对湿度较低的情况下，石膏粉经水溶性硬石膏反应后，其含水量可以达到一定的水平。如果空气相对湿度偏高，水化反应继续，可形成二水石膏，对石膏粉质量和生产稳定控制带来不利影响。一般来说,石膏粉的企业存储和使用它的性能进行测试,这样可以判断石膏粉模具需求,同时根据石膏粉的性能指数调整生产石膏模型的参数,以满足模具的要求。

　　The research results of foreign scholars show that the moisture content and rheological properties of gypsum powder vary with the storage time, which is due to the aging process of gypsum in the air. The process can be divided into two stages: one is the rapid hydration of soluble anhydrous gypsum (anhydrous gypsum) to form hemihydrate gypsum; the absorption rate of water by hemihydrate gypsum is very slow, so that the crystal transformation is completed, and the mixed water volume gradually decreases. When the relative humidity of air is low, the water content of gypsum powder can reach a certain level after the reaction of water-soluble anhydrite. If the relative humidity of air is relatively high and the hydration reaction continues, dihydrate gypsum can be formed, which has adverse effects on the quality and production stability control of gypsum powder. Generally speaking, gypsum powder enterprises store and use its performance to test, so as to judge the demand of gypsum powder mould, and adjust the parameters of the production model according to the performance index of gypsum powder to meet the requirements of the mould.