نتایج جستجو برای: rangelands that converted to rainfed agriculture
تعداد نتایج: 11025361 فیلتر نتایج به سال:
soil salinity is one of the problems threatening agricultural lands. parts of this phenomenon are related to geologic formations and saltpans, while some major factors are resulted from irrelevant agricultural activities, issue of irrigation, and improper cultivation systems which lead to increase in soil salinity. to avoid such consequences that would end up with ecosystem degradation, suitabl...
With a growing world population and a trend towards more resource-intensive diets, pressure on land and water resources for food production will continue to increase in the coming decades. Large parts of the world rely on rainfed agriculture for their food security. In Africa, 90 % of the food production is from rainfed agriculture, generally with low yields and a high risk of crop failure. One...
soil conservation is one of the most important regulative functions of natural ecosystems. this function is of high importance in taleghan watershed due to high erosion quantity and sediment accumulation in taleghan dam reservoir. soil loss reduction, sedimentation control and fertility conservation were considered as different aspects of soil conservation. effect of land use and vegetation cov...
This study examined the performance and future predictions for the Middle East produced by 18 global climate models participating in the Intergovernmental Panel on Climate Change Fourth Assessment Report. Under the Special Report on Emission Scenarios A2 emissions scenario the models predict an overall temperature increase of ∼1.4 K by mid-century, increasing to almost 4 K by late-century for t...
Humans and the ecosystem services they depend on are threatened by climate change. Places with high or growing human population as well as increasing climate variability, have a reduced ability to provide ecosystem services just as the need for these services is most critical. A spiral of vulnerability and ecosystem degradation often ensues in such places. We apply different global conservation...
Soil salinity is one of the problems threatening agricultural lands. Parts of this phenomenon are related to geologic formations and saltpans, while some major factors are resulted from irrelevant agricultural activities, issue of irrigation, and improper cultivation systems which lead to increase in soil salinity. To avoid such consequences that would end up with ecosystem degradation, suitabl...
Agriculture in Lorestan Province is based on irrigated and rainfed agriculture, which uses two sources of surface water and groundwater. One of the most important natural hazards affecting the Lorestan Province agriculture is the occurrence of drought and its consequences. The main purpose of this study is to investigate the effects of drought on irrigated agriculture in this province. The data...
The Great Plains of North America encompass approximately 85 million ha (210 million acres) consisting of shortgrass, mixed-grass, and tallgrass prairie with about 60% of this area converted to crop agriculture and the remainder used primarily for livestock production. Large-scale gradients of precipitation (west to east, <30 to >100 cm; <12 to >40 inches) and mean annual temperature (north to ...
With the growing recognition of the possibility of global climate change, an increasing emphasis on world food security in general and its regional impacts in particular have come to forefront of the scientific community. Agriculture production of rainfed regions is expected to suffer severe water crisis due to delayed monsoon, uneven distribution of rain as a result of climate change. The impa...
in this thesis, a new optically active poly(amide-imide) (pai) was synthesized by the indirect polycondensation reaction of the l-phenylalanine based diacid chloride and 4,4?-diaminodiphenylether in the presence of triethylamine in n-methyl-2-pyrrolidone. the formation of pai was confirmed by ftir, 1h nmr and elemental analysis. in next step, the surface of titanium dioxide (tio2) nanoparticles...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید