We report the rapid acidification of forest soils in the San Bernardino Mountains of southern California. After 30 years, soil to a depth of 25 cm has decreased from a pH (measured in 0.01 M CaCl2) of 4.8 to 3.1. At the 50-cm depth, it has changed from a pH of 4.8 to 4.2. We attribute this rapid change in soil reactivity to very high rates of anthropogenic atmospheric nitrogen (N) added to the ...

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...

in order to study the effects of sugar cane harvest machinery traffic on bulk density and cone index variation, a survey was conducted in 10 farms of deabel khozaiee sugarcane agro-industrial company, ahvaz, in 2006. in this experiment, two types of harvesters including wheel half track and tire wheels with 14 tons of weight, versus two types of tractor and basket transporters, with 10 and 18 t...

Methyl bromide (CH,Br) is currently the most widely used soil fumigant, and its emission into the atmosphere after application reportedly contributes to ozone depletion in the stratosphere. Irreversible degradation and partially reversible sorption reactions affect the quantity of this fumigant reaching the soil surface and escaping into the atmosphere. Incubation studies in closed headspace vi...

Spatial variability in soil properties has long been observed within uniformly managed fields. Understanding the spatial characteristics of soil properties would be helpful in understanding soil–landscape relationships and in the development of site-specific management. The primary objective of this research was to quantify the spatial characteristics of claypan soil properties for a 4-ha agric...

From the end of 1996 through March 1999, the spatial and temporal variability of the soil 222Rn concentration was investigated at a 20 m x 20 m test field with porous soil in 0.5 m and 1.0 m depth at nine positions each and at 1 m x 1 m plots at four positions each. For this, soil gas was collected weekly into evacuated scintillation cells and was analysed subsequently for radon activity. In th...

Agronomic practices, climatic variables, and soil conditions are key factors in crop productivity. Although the effects of soil chemical properties and water and agronomic crop management are known, there is little information about effective soil depth and its influence on crop productivity. Since most crop fertilization systems are based on the productive potential associated with climatic co...

Over three million hectares of salt-affected soils characterized with high salinity and sodicity caused serious land degradation in Songnen Plain, northeast China. Soil salinity–sodicity heterogeneous distribution under microtopography is usually influenced by several environmental factors. The side direction movement of soil water driven by water from depression is the key factor that aggravat...