sentences:  Like other legumes, its root nodules contain bacteria, "Sinorhizobium meliloti", with the ability to fix nitrogen, producing a high-protein feed regardless of available nitrogen in the soil.Its nitrogen-fixing ability (which increases soil nitrogen) and its use as an animal feed greatly improve agricultural efficiency.Alfalfa can be sown in spring or fall, and does best on well-drained soils with a neutral pH of 6.8–7.5.