For the last year or two it is now the fashion to plant plants in between the rows of vines and on land that is fallow that replenish the soil (as they did 100 years ago). Many of these are leguminous (clover, pea such as vetch, bean, alfalfa, lupin – the Fabaceae family) which naturally create nitrogen and ‘recharge’ the soil. What they do is to ‘fix’ atmospheric nitrogen into the soil by bacteria in nodules in their roots which convert it into the more accessible ammonia. Most nitrogen is available to the plant by some form of organic matter.
Its like magic and the effect they have on the soil is to promote growth.
Or the crops can be planted like a ‘green manure’ in between the rows to nourish the vines at intervals through their life.