Frontier areas in Latin America have been characterized by land speculation, abandonment and exploitation. This paper analyzes a frontier cattle ranching area in the savanna where intensification has occurred in spite of land speculation. A whole farm livestock production model is used to quantify the determinants of intensification. Results show that land speculation has simultaneously increased the profitability of cattle ranching while slowing down intensification and impeding the adoption of sustainable practices.

In a selected study are in Pucallpa, Peru, 151 farmer-settlers were interviewed to understand current land use dynamics. Respondents were stratified according to broad differences determined by preliminary informal surveys. Settlers included: farmers practicing slash-and-burn agriculture in upper forested areas, slash-and-burn farmers living along rivers, small-scale cattle ranchers with lands located largely along the road connecting Pucallpa to Lima, and a subset of forest slash-and-burn farmers who had established oil palm as a cash crop.

The results of a case study conducted in Betulia (Sucre, Colombia) in May-Dec. 1983 to evaluate the competition for land between cassava cultivation (monocropped or in association with maize or yam) and cattle raising are discussed. In general, profits from cassava either in association or in monoculture are much higher than for cattle raising. Regarding labor requirements, cassava cultivation and cattle raising are equally attractive from an economic viewpoint.

The distribution of Trichoderma species in soils of Embu region in relation to land use practices was investigated. The study area was chosen because of its significant land use intensification. Soil washing and dilution plate techniques were used to recover Trichoderma spp from soil samples. The fungal isolates were identified and assigned to eight species. Greater populations as well as a wider range of species were obtained in soils collected from the natural forests while coffee farms were the poorest ones. Land use affected the distribution of Trichoderma.

The effect of land use on the availability of soil nitrogen (N) was studied by separating total soil N into one labile and one stable fraction by oxidation and extraction of labile N with potassium permanganate. The nitrogen management index (NMI) was calculated according to Blair et al. (1995) for the carbon management index. In all systems, labile N released by potassium permanganate was a better indicator for nitrogen availability than were total and stable N. The NMI was a good indicator for N availability but gave no information on the total amount of N.