These examples can be taken as typical of what has happened wherever native vegetation has been cleared and replaced by pasture. There has been no competition between native and introduced species, either for food or for living space. All but subsoil species among the native earthworms have died out before the introduced lumbricids became established, and the few subsoil earthworms that have re...

Soil organic carbon (SOC) from aboveground and belowground sources has rarely been differentiated although it may drive SOC turnover and stabilization due to a presumed differing source dependent degradability. It is thus crucial to better identify the location of SOC from different sources for the parameterization of SOC models, especially in the less investigated subsoils. The aim of this stu...

To determine root growth and grain yield of winter wheat (Triticum aestivum L) under moderate drought stress, a nursery experiment and a field trial were conducted with or without water stress using three representative cultivars released in different years: CW134 (old landrace), CH58 (modern cultivar) and CH1 (new release). In the nursery experiment, plants were grown in soil-filled rhizoboxes...

SOILS in the humid tropics are known for their low retention capacity of nutrients and high susceptibility to leaching (Van Wambeke, 1992). Nitrogen is particularly susceptible to leaching losses since mineralization and nitrification both proceed very rapidly under humid tropical conditions and because nitrate is very mobile in most soils. In central Amazonian Oxisols, a large accumulation of ...

Two field trials were sampled to investigate the changes to soil solution chemical properties of a yellow sandplain soil with an acidic subsoil following the application of gypsum and lime to the soil surface in 1989. The soils were sandy textured and located in a region of low annual rainfall (300-350 mm). Soil was sampled annually to a depth of 1 m and changes in soil solution composition wer...

Rising temperatures in the Arctic can affect soil organic matter (SOM) decomposition directly and indirectly, by increasing plant primary production and thus the allocation of plant-derived organic compounds into the soil. Such compounds, for example root exudates or decaying fine roots, are easily available for microorganisms, and can alter the decomposition of older SOM ("priming effect"). We...

The experiments were conducted at Green Acres Agronomy farm near Gainesville, Florida, on an Arredondo loamy sand, a member of the loamy, silicious, hyperthermic family of grossarenic Paleudults. The field study started in 1976 included cropping systems of oat (Avena sativa)/soybean (Glycine max L. Merr.) versus oat/grain sorghum (Sorghum bicolor L.) that were split plots of four tillage treatm...

Soil organic carbon (SOC) and nitrogen (N) contents are controlled partly by plant inputs that can be manipulated in agricultural systems. Although SOC and N pools occur mainly in the topsoil (upper 0.30 m), there are often substantial pools in the subsoil that are commonly assumed to be stable. We tested the hypothesis that contrasting long-term management systems change the dynamics of SOC an...

Increase in the bulk density of a Grey Clay subsoil by infillings of cracks by topsoil Summary Increases in soil bulk density beyond the optimum reduce land productivity and, where soil is affected, may be difficult to remedy. Elucidating the mechanisms causing compaction is a prerequisite to sustainable management of fragile soils. We examined a dense grey soil in Western Australia in which th...

We hypothesized that the integration of trees into agricultural land-use systems can reduce NO., leaching and increase subsoil N utilization. A field study was conducted on a Kandiudalfic Eutrudox (Ochinga site) and a Kandic Paleustalf (Muange site) in the subhumid highlands of Kenya to measure changes in soil NO, and water to 200-cm depth for one rainy season in four land-use systems (LUS): (i...