Biofuel demand is increasing because of a combination of growing energy needs; rising oil costs; the pursuit of clean, renewable sources of energy; and the desire to boost farm incomes in developed countries. In turn, the need for crops-such as maize and sugarcane-to be used as feedstocks for biofuels has increased dramatically. That demand has had a significant and increasing impact on global food systems. The effects of growing biofuel demand are interwoven with tightening grain markets, which reflect demographic shifts and improved diets.

"This article analyzes the on-site and off-site economic impacts of various sustainable land management (SLM) practices in Kenya. Long-term trial data are used to establish the relationship between SLM practices and maize yield. The analysis of on-site effects focuses on the profitability of maize production at the farm level, while the examined off-site effects include carbon sequestration and siltation from maize farms, which increase the cost of potable water production.

La demanda de biocombustibles se está incrementando debido a la necesidad cada vez mayor de energéticos, el alza en el costo del petróleo, la búsqueda de fuentes de energía renovables y no contaminantes y el deseo de aumentar los ingresos agrícolas en los países en desarrollo. Asimismo, ha aumentado en forma drástica la necesidad de contar con cultivos, como el maíz y la caña de azúcar, que pueden utilizarse como materia prima para producir biocombustibles. Esta demanda ha tenido a nivel mundial un impacto significativo y cada vez mayor en los sistemas alimentarios.

Although wild natural resources are a standard dietary component in southern Africa, little information exists on these resources' specific role in the maintenance of household food security among HIV-impacted households. In this context, the influence of cash savings or income generated through use or sale of natural resources (e.g., using fuelwood instead of electricity to be able to afford to buy food) is also not known.

The effect of land cover change, from natural to anthropogenic, on physical geography conditions has been studied in Kayisdagi Mountain. Land degradation is the most important environmental issue involved in this study. Most forms of land degradation are natural processes accelerated by human activity. Land degradation is a human induced or natural process that negatively affects the ability of land to function effectively within an ecosystem.

Poverty reduction and sustainable land management are two objectives that most Africancountries strive to achieve simultaneously. In designing policies to achieve theseobjectives concurrently a clear understanding of their linkage is crucial. Yet there isonly limited empirical evidence to demonstrate the linkage between poverty and land managementin Africa. Using Uganda as a case study, this analysis seeks to better understand thislinkage. We used several poverty measures to demonstrate the linkage between poverty and anumber of indicators of sustainable land management.

Land degradation is always with us but its causes, extent and severity are contested. We define land degradation as a long-term decline in ecosystem function and productivity, which may be assessed using long-term, remotely sensed normalized difference vegetation index (NDVI) data. Deviation from the norm may serve as a proxy assessment of land degradation and improvement - if other factors that may be responsible are taken into account. These other factors include rainfall effects which may be assessed by rain-use efficiency, calculated from NDVI and rainfall.

It is known that erosion is a leading factor in land degradation. Therefore, erosion must be correctly estimated and effective precautions must be taken for a sustainable agricultural activity. Hence, many models and methods have been developed for estimation of soil erodibility or calculating of quantity of the soil loss. In the present paper, using of fuzzy logic based models were examined in soil erosion prediction studies. For this goal, binary logic was described and then the transition from the classical logic to fuzzy logic has been studied.