PROBLEM TO BE SOLVED: To augment the yields of crops harvested by physical treatment alone because there is a limit in augmenting the yields of grasses and legumes by treating grass seeds such as the seed rice of waterfield rice and the seed of corn and legume seeds such as soybean through genetic engineering techniques or hybrid technology and the genetic engineering techniques still make feel uneasy about their safety aspects. SOLUTION: Plant seeds are exposed to the magnetic field and then are exposed to an electric field on a flat board made of gray iron before being sowed. In the case of grass seeds, they are preferably soaked in special water previously subjected to both of electric field processing and magnetic field processing after that. Thereby, genes for the germination and growth of seeds are activated, which leads to the augmentation of yields.