Soil h2o likely checking: a gypsum block could be inserted into the soil, and its electrical resistance can be measured to derive soil humidity.[48] Crystal Technique: Gypsum crystals belong into the monoclinic crystal method. This crystal structure has 3 unequal axes, with 1 angle concerning axes remaining non-ninety levels. From https://www.propanraya.com/id/produk/eco-gypsum-ee-4050