the purpose of this study is the analysis of the farmers economic behavior to reduce the adverse environmental effects of agricultural chemical inputs by using contingent valuation approach and tobit model by heckman's two stage. to achieve the desired goal, 100 questionnaires collected by a random sampling from farmers of kashaf- rood basin in mashhad city in 2013. results showed that variable...

Seasonal and spatial variation in soil nematode communities was investigated in a field study conducted on a loessial plain in the northern Negev Desert, Israel. Soil samples from 0- to 50-cm depths were collected seasonally during 2001 under the canopy of Atriplex halimus and Hammada scoparia, and between shrubs (control). Total population abundance ranged from 8 to 887 individuals per 100 g s...

Hyperspectral reflectance derived vegetation indices (VIs) are used for non-destructive leaf area index (LAI) monitoring for precise and efficient N nutrition management. This study tested the hypothesis that there is potential for using various hyperspectral VIs for estimating LAI at different growth stages of rice under varying N rates. Hyperspectral reflectance and crop canopy LAI measuremen...

A new moisture adjusted vegetation index (MAVI) is proposed using the red, near infrared, and shortwave infrared (SWIR) reflectance in band-ratio form in this paper. The effectiveness of MAVI in retrieving leaf area index (LAI) is investigated using Landsat-5 data and field LAI measurements in two forest and two grassland areas. The ability of MAVI to retrieve forest LAI under different backgro...

Soil salinity / alkalinity development is one of the major land degradation problem affecting sustainable agricultural productivity in irrigated areas of arid and semi arid regions of the world. The characterization and mapping of salt affected soils is difficult as the salt concentration may vary substantially over short distances. Various broadband multi-spectral satellite data and spectral i...

Soil microbes play an essential role in the forest ecosystem as an active component. This study examined the hypothesis that soil microbial community structure and metabolic activity would vary with the increasing stand ages in long-term pure plantations of Pinus elliottii. The phospholipid fatty acids (PLFA) combined with community level physiological profiles (CLPP) method was used to assess ...

Drought is one of the major natural hazards that bring about billions of dollars in loss to the farming community around theworld each year. Drought is most often caused by a departure of precipitation from the normal amount, and agriculture is often the first sector to be affected by the onset of drought due to its dependence on water resources and soil moisture reserves during various stages ...

Tracking the presence, distribution and disappearance of biological soil crusts is important for ecosystem management of desert regions and provides highly valuable information on desertification and climate change studies in arid environments. Based on the analysis of the spectral features of biological soil crusts, we propose a new biological soil crust index (BSCI) for biological soil crusts...

the engineering properties of soils are generally affected by parameters such as mineral type, structure, and pore water salinity. the existing solutes of soil play a role in the electrochemical forces between particles and can change the index and mechanical properties of soil, including cohesion, compressibility, and compactibility. this study investigated the effect of sodium chloride, sodiu...