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White Spot, Deep Tillage and Water Infiltration of the Portneuf and Related Silt Loam Soils

Rasmussen, W.W. and Cary, J.W. (1979) White Spot, Deep Tillage and Water Infiltration of the Portneuf and Related Silt Loam Soils. University of Idaho Current Information Series No. 460. University of Idaho College of Agriculture. 4 pp.

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The Portneuf silt loam and related soils of southcentral
Idaho have formed from wind-laid material (loess)
deposited over the thick lava of the Snake River Plains.
Extensive areas of these soils are irrigated cropland.
They are considered some of the most valuable and
productive soils in Idaho. The soils have a lime (calcium
carbonate) cemented hard-pan layer beginning about 14
inches below the surface and extending to depths of 30 or
40 inches in the soil. The hard layers allow irrigation
water to move down but restrict most plant roots.
Because of this, the water and nutrients that move
through and below the hard layers are only slowly
available to most annual crop plans.
These high silt soils are extremely susceptible to erosion,
especially under the common methods of furrow
irrigation. Land grading has further depleted the
valuable topsoil on many fields. If the fields are cut and
graded, or severely eroded, material from the hard
layers may be brought to the surface by tillage. Because
of the hard layers' high lime content and low organic
matter, the surface color becomes lighter and is known
as a white spot. Crop yields from white spots are reduced.
The loss of valuable topsoil and the resultant depleted
soil fertility are considered the most important soil
problems in this region of Idaho. Methods for eliminating
soil erosion caused by irrigation and for improving the
already eroded and denuded white spot soils are urgently

Item Type: Technical Bulletin
NWISRL Publication Number: 0438
Subjects: Irrigation > Furrow irrigation > Infiltration
Soil > Tillage
Mass Import - autoclassified (may be erroneous)
Depositing User: Dan Stieneke
Date Deposited: 20 Nov 2010 21:58
Last Modified: 27 Oct 2016 15:21
Item ID: 1162