c. Loss of forage legumes.
An important type of degradation that is frequently unnoticed is the loss of native leguminous forages. This is quite serious; such legumes are usually highly palatable, nutritious, and a major source of mineral nutrients that are indispensable to reproduction, growth of young animals, and milk flow. Moreover, such legumes are the prime source of nitrogen in most grasslands, which is "fixed" by root nodules by drawing on nitrogen in the soil air to produce proteins in all forage plants. Destruction of legumes by overgrazing is much more rapid than loss of grass cover, and such loss cuts off the major source of nitrogen for the rangeland or other permanent grasslands. Since it is rarely feasible to apply nitrogen fertilizers to grasslands particularly in semi-desert or savanna regions, the loss of legumes results in a sharp decline in capacity of the grasslands or rangeland to produce forage, and a similar decline in the nutritive value of the forage and in productivity of livestock herds and flocks.
For virtually all ecological conditions, there are forage legumes that are adapted to local conditions of climate and soil, and will survive and multiply under careful management. This potential is astonishingly effective where legume protection and management has been followed. It is highly unlikely to occur however, without the skillful intervention by man in managing his grazing lands.