The results obtained from the investigations achieved the goals that were initially considered:

• To know the inlets and outlets of nutrients in the soil-fodder system and to establish functional relations of this process,
• To develop simulation models (Software) of the recycling process
• To simulate and validate the Software to a commercial scale.

In the first stage, it was characterized the recycling of nutrients through animals’ excretions (excrements and urines), where the following aspects were determined:

• quantity, weight or volume and pasture land area covered by both types of excretions;
• effect in soil and in fodder, decomposition rate and nutrients released by the excretions and ammonia volatilized by these.

It was also investigated in this stage the accumulation capacity, the decomposition rate and the liberation of nutrients from fallen leaves of 5 leguminous plants and of 7 perennial pasturage gramineous and the models that simulate these processes. It was also investigated the soil macrofauna's diversity and biomass in ecosystems that varied from pure pasture lands of artificial or natural gramineous plants, until compound pasture lands for 100% of leguminous plants in the area. Other aspects were also studied, such as the biomass of pasture's roots and its nutrients contribution, as well as the rain share in N contribution.

In the second stage, the balance and the flow of nutrients in three production systems of bovine livestock were analyzed, where the following indicators were measured:

• Disponibility and rejection of pasture
• Nutrients extracted from the soil,
• Acumulation and decomposition rates of fallen leaves and nutrients released through this way,
• Excrements and urine laid by the cattle and nutrients recycled by them,
• Area covered by the excretions,
• Nutrients’ inlets with other food,
• N’s inlet for rain,
• Nutrients extracted by animal products, and removilization of nutrients by pasturage.

It was found a negative balance of N (=15 kg. of N/ha), P (=6 kg. of P/ha) and K (=17 kg. of K/ha) in the system of fatting livestock pasturage with native pasture land and positive balance of N and P in the pasturage system with L. Leucocephala in 100% of the area; in turn, in a milk production system, where the pasture land was composed by 60% of C. nlemfuensis and 60% of P.