Agriculture and silviculture are seen as an alternative for countryside producers of the Third World country and for countries in development. For its integration of forest with agricultural crops and with cattle raising, the system offers an alternative to face the chronic problems of low productivity, food lack, environmental degradation and reduction of risks of production losses due to crop diversification. Besides that, it is possible to have a return of invetment in a faster way and it makes possible to the farmaer to have an income until the forest is adult and produce wood to be commercialized. With this system, it is possible to get efficient gains in the following aspects: Agronomic (better soil conditions), economic (diversification of production), ecological (improvement of biodiversity, hydrology and macroclimate), and also social (direct and indirect social benefits).

The agriculture-forest system shows great advantages related to the to conventional systems of soil use because it allows bigger diversity and sustainability. From an ecological point of view, the coexistence of more than onde species in the same area allows better use of water and nutrients. The cycle of nutrients tends to be faster and they are better used by intercalate crops. It should be taken iinto account the demand that trees and the crops require in terms of sapce, nutrients and water. It is necessary to reckon how trees could interfere in agricultural production. The results should allow the evaluation that these two crops produce more even if the two of them were separately cultivated.

Eucalyptus behaves as a forest species of multiple use, it can produce wood, shadow, shelter, honey ans essential oil; and it also has high productivity and capacity of reborning, besides having a relatively open top leaving light do inside. With an adequate control of the density of eucalyptus plantation, it is possible to have an economical return along with other crops. Moreover, the agriculture-forest system reduces the losses of soil nutrients, improves the soil protection during the critical phase of baby plants, when the soil is unprotected, and reduces the costs of soil preparation. The use of eucalyptus species in these systems have been made for some time in several countries because they are searching for a kind of social reforestingprograms, on which eucalyptus is being used in plantations in small farms.

After a complete cycle of harvest, it is started another cycle, repeating the crops and the procedures eith the use of blooming of the eucalyptus. For that, cattle is taken off the area, wood is harvest and herbicide is applied in the in-between lines of rice, soy or other agricultural crop. Preliminary results of the second cycle show bigger productivity in grains, meat and wood, showing the efficiency of thissystem. The productivity of grains in the second cycle was 15 - 20% bigger than in the first cycle and wood productivity was more than 20%. Besides the economical advantages, such results show important enviromental answers that some people and pseudo scientists are trying to ignore on the behavior and crop effect of eucalyptus on other crops. Such answers show that all crops in this case (eucalyptus, rice, soy and grass) got benefits of this kind of crop.

The agriculture-forest system practiced by the Companhia Mineira de Metais is innovative by its conception of sustainable development and it is in perfect synchrony with the wishes and social appeals of productive systems, using, in an eficient and rational way, the natural resources and using simultaneous spaces to produce food, fibers and energy. The system has an alternative to minimize the initial costs of implementation and maintenance of forest plantations allowing the cash flow for a long period of forest growing, besides supplying complementary incomes.