The impact of forest land use change to intensive agricultural system on the economic efficiency of nitrogen utilization

Identifying the dynamics of N-mineral soils in different Land Use Systems (LUS) with different levels of intensification, seven LUS were studied as well as intensive horticulture gardens. The coffee garden observed as of 7 - 10 years old. Measurements were made twice in the rainy and dry seasons. The use of forest land into coffee plantations and horticulture gardens was significantly (<0.05) to total-N, very significant (<0.01) to NO3- soil concentrations, but did not significantly affect the soil NH4+ concentration. Horticultural land has the lowest NH4+/N-mineral soil concentration ratio (0.98%) when it is compared to other LUS. The highest soil NO3- concentration (about 1400 mg kg(-1) soil) was found in intensive farming areas ie horticulture, about 5-17 times higher than in other LUS. The more intensive the land use system is followed by the increasing ratio of N-mineral/N-total soil concentration as well as the decrease in the NH4+/N-mineral soil concentration. This indicates that the more intensive the LUS will further decrease the economic efficiency of N utilization and increase the potential for loss of N through NO3- leaching, NO2 and NO evaporation, as well as run off, and potentially adverse impacts on aquatic biota due to eutrophication. This will lead to environmental damage, especially water pollution.