Recently, land managers have looked to fallow agricultural lands such as paddy fields as possible areas for pasturing cattle. To skillfully manage such lands as grasslands, it is important to understand the size of the areas in question. The hand-held GPS with an external antenna might have an acceptable margin of error for measuring areas of fallow land. GPS technologies easily can be applied to quickly obtain information on field conditions. Festulolium is moisture-proof and is a promising herbage species that could yield herbage mass and the same level of quality as annual ryegrass even with bad drainage following thawing. Mulberry fields can be developed well into grasslands by barking the trunks of mulberry trees without felling them during the sprouting stage in the spring and sowing the handmade herbage seed pellets in the autumn, which could reduce labour and money. The number of affiliative behaviours was greater in cows grazed in abandoned paddy fields than in animals grazed in pasture in large groups. Urinary cortisol levels, which were used as an indicator of stress, were almost the same between the two cattle groups. Grazing of beef cows from the same farmer in an abandoned paddy field was thus not inferior to grazing in pasture with respect to animal behaviour and physiology. The daily body-weight gain of breeding calves being grazed in the small Festulolium pasture of less than 0.6 ha ranged from 0.38kg to 0.46kg, which was a sufficient growth rate for breeding cows. From these results, we conclude that grassland development and small-scale grazing techniques in fallow fields would be useful to boost the rate of self-sufficiency in herbage and solve the problem of the increasing amount of fallow land in Japan.