To the maximum extent feasible, organic farming systems rely on crop rotations, crop residues, animal manures, legumes, green manures, off-farm organic wastes, and aspects of biological pest control to maintain soil productivity and tilth, to supply plant nutrients and to control insects, weeds and other pests. The modern knowledge about soil fertility, parasite life-cycles, crop and livestock requirements has enabled a set of management tools to be developed for organic farmers which keeps production to a maximum. Although low in external chemical input, organic farming requires high inputs of skills and management. In grassland, animal rotations are essential to control parasite infestation in livestock, weed infestation and to maintain a proper nutrient balance in silage and pasture land. The type of rotation is dependent on the farming system.
Older animals tend to build up natural resistance to stomach and lung parasites.
Therefore, rotational grazing systems are primarily aimed at reducing the exposure of younger animals to infections and maintaining a productive high-clover sward. Alternating silage ground and pasture will keep nutrient levels of individual fields in balance. While nutrient levels may not decrease significantly on pastures, they fall rapidly with the removal of silage or hay. Nutrients can be restored by applying dressings of farmyard manure. Weeds like docks and ragworth can be controlled by grazing infested pastures with sheep in early Spring.