Ammonia-oxidising archaea (AOA) and bacteria (AOB) are responsible for the rate limiting step in nitrification; a key nitrogen (N) loss pathway in agricultural systems. Dominance of AOA relative to AOB in the amoA gene pool has been reported in many ecosystems, although their relative contributions to nitrification activity are less clear. Here we examined the distribution of AOA and AOB with d...

Brassicas have been used frequently for biofumigation, a pest-management strategy based on the release of biocidal volatiles during decomposition of soil-incorporated tissue. However, the role of such volatiles in control of plant-parasitic nematodes is unclear. The goal of this study was to determine the direct localized and indirect volatile effects of amending soil with broccoli tissue on ro...

soil compaction reduces growth of secondary roots, soil aeration and water and mineral uptake by plant, and decreases chlorophyll content as well as root yield and sugar content. hence, the effect of soil compaction on sugar beet yield and sugar content farms determined by penetrometer using 40 plots of 100 m2 in 40 sugar beet field of hamedan, asadabad, malayer and bahar at the depth of 0-80 c...

plant performance and freshness is related to the pattern of its root growth development, which is highly affected by the water amount and water use management. therefore, the spatiotemporal variation of maize root under five treatments including full irrigation treatment (fi), partial root-zone drying treatments at two levels (receiving 75% of et =prd75, and 55% of et= prd55) and deficit irrig...

The surface material at the Surveyor 5 site is granular and slightly cohesive. Spacecraft footpads plowed trenches in this material as the spacecraft slid during landing. For a compressible soil model, a static bearing capacity of 2.7 newtons/cm •' gave best agreement with the observations. Static firing of the vernier engines against the surface moved surface particles; a crater 20 cm in diame...

There is little comprehensive information on the distribution of root systems among coexisting species, despite the expected importance of those distributions in determining the composition and diversity of plant communities. This gap in knowledge is particularly acute for grasslands, which possess large numbers of species with morphologically indistinguishable roots. In this study we adapted a...

In the Whitehall Forest of Georgia during the 1985-86 non-growing season soil CO, varied with soil depth, varied spatially at constant depth, and varied temporally with changing environmental conditions. Variations with depth in the upper 1.4 m of the soil were of greater magnitude than temporal variations and spatial differences at 30 cm depth were of lesser magnitude. Mean soil CO, in evergre...