Microbial breakthrough curves of 12 soils, generated by the application of dairy shed effluent followed by continuous artificial rainfall for one pore volume at 5 mm h(-1) onto large undisturbed soil cores, have been ranked as high, medium, or low potential for microbial bypass flow. The ranking is based on the position of the peak in the breakthrough curve. Knowledge of soil properties that af...

Reuse of saline subsurface drainage water for irrigation has been identi®ed as a potential option for managing drainage volumes and sustaining crop productivity in California's San Joaquin Valley. Soil surface structural instability, crusting and poor stand establishment may, however, be constraints in drainage reuse systems. The objective of this ®eld study was to evaluate the effectiveness of...

[1] The hydrologic response of upland watersheds is strongly controlled by soil (regolith) thickness. Despite the need to quantify soil thickness for input into hydrologic models, there is currently no widely used, geomorphically based method for doing so. In this paper we describe and illustrate a new method for predictive mapping of soil thicknesses using high-resolution topographic data, num...

In situ volumetric soil-water contents were measured on 11 days at 0.20 m depth intervals to 1.0 m in a field experiment with four replicates of a dry-land corn hybrid (Pioneer 3140) at plant populations of 37, 49, and 62 thousand plants haÿ1. These measurements were used to estimate total soil-water losses in each of the 12 field plots for each of the 10 measurement intervals. The area of the ...

abstract by increasing the world population and more need to supply food, farmers attend to use of chemical fertilizers, organic manures and pesticides. also, applications of these agents without attention to their side effects, cause more problems to human health and environment. nitrate is one of the most important elements of organic manures, which leach through soil to surface and ground wa...

Plant salt stress is a condition where excessive salts in soil solution cause inhibition of plant growth or plant death. On a world scale, no toxic substance restricts plant growth more than does salt. Salt stress presents an increasing threat to plant agriculture. Among the various sources of soil salinity, irrigation combined with poor drainage is the most serious, because it represents losse...

Tom Scherer Extension Agricultural Engineer The presence of salts and high water tables in North Dakota soils due to an extended climactic wet cycle recently has stimulated interest in the installation of tile drainage systems. The tile controls the water table and encourages the leaching and removal of salts from the soil above the tile lines. This improves soil productivity, culminating in im...

Nonpoint source contamination of surface and groundwater resources with nitrate-N (NO3-N) has been linked to agriculture across the midwestern USA. A 4-yr study was conducted to assess the extent of NO3-N leaching in a central Iowa field. Water flow rate was monitored continuously and data were stored on an internal datalogger. Water samples for chemical analysis were collected weekly provided ...