A purely mechanical method can produce a novel, more sustainable fertilizer in a less polluting way. That is the result of a method optimized at DESY's light source PETRA III. An international team used PETRA III to optimize the production method that is an adaptation of an ancient technique: by milling two common ingredients, urea and gypsum, the scientists produce a new solid compound that slowly releases two chemical elements critical to soil fertilization: nitrogen, and calcium.