S' OME eighty years ago, when Dokuchaev (Margulis, 1954) distinguished five natural soil zones tundra, podzol, chernozem, desert, and laterite -the stage was set for a systematic study of soils as naturally occurring bodies. Of these, the tundra has received by far the least attention. European investigators, notably the Russians, have made many studies of the northern regions but in North Amer...

[1] Understanding and quantifying the long-term suspended sediment discharge of drainage basins is a key goal of geomorphology, with important implications for the study of water quality, agricultural sustainability, and the evolution of landscapes and sedimentary basins over geologic timescales. Previous studies have highlighted the importance of relief/slope, precipitation, temperature, veget...

The impact of long-term grassland management regimes on microbial community structure in soils was assessed using multivariate analysis of polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) banding patterns of selected bacterial groups and PLFA (phospholipid fatty acid) profiling. The management regimes assessed were inorganic nitrogen (N) fertiliser application and so...

Arctic landscapes are characterized by a diversity of ecosystems, which differ in plant species composition, litter biochemistry, and biogeochemical cycling rates. Tundra ecosystems differing in plant composition should contain compositionally and functionally distinct microbial communities that differentially transform dissolved organic matter as it moves downslope from dry, upland to wet, low...

In agricultural lands, high nutrient levels of nitrogen, phosphorus and potassium are very important due to the high need of plants. By improving the nutrient content of sodium soils, the fertility and growth of the plants improve. Accordingly, in order to investigate the effect of underground drainage on soil quality in Khuzestan region, this experiment was carried out in a completely randomiz...

Insufficient water is the greatest limitation to crop production and choice of crops grown in the Northern Great Plains. Supplemental irrigation can overcome this limitation. Uncertainties about the drainage capacity of flne-textured subsoils and the effect of irrigation on soil properties has impeded irrigation development. In this study we quantified salinity changes in soils with fine-textur...

The sustainability of irrigated agriculture in India is threatened by waterlogging, soil salinity, and alkalinity. To reverse declining agricultural productivity, a combination of surface and subsurface drainage, supplemented by improved irrigation management, has been identi®ed as the most appropriate strategy. But subsurface drainage for salinity control is costly. Therefore, its bene®ts in t...

This study aimed to determine phosphorus (P) concentration using reflectance spectra of grass and soils in the Lake Okeechobee drainage basins, Florida. A total of 150 grass samples and 150 soil samples were collected from the three sites in the Lake Okeechobee drainage basins. The reflectance spectra of both fresh and dried samples for grass and soil were measured using UV, VIS, and NIR spectr...

Plant rooting depth affects ecosystem resilience to environmental stress such as drought. Deep roots connect deep soil/groundwater to the atmosphere, thus influencing the hydrologic cycle and climate. Deep roots enhance bedrock weathering, thus regulating the long-term carbon cycle. However, we know little about how deep roots go and why. Here, we present a global synthesis of 2,200 root observ...