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Water conservation under reduced tillage systems

Ramig, R.E. and Saxton, K.E. and Massee, T.W. and Campbell, G.S. and Thill, D.C. (1987) Water conservation under reduced tillage systems. In: STEEP--Conservation Concepts and Accomplishments. Washington State University Publication, Pullman, WA. pp. 125-136.

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Water is important for dryland crop production. Seldom is rainfall
sufficient or adequately distributed during a growing season so that dryland
crops can produce to their fullest potential. It is necessary to have
stored water available in the soil to supplement inadequate growing season
rainfall for economical crop production. Stored water is especially
important in the Inland Pacific Northwest of north central Oregon,
southeastern Washington, and northern Idaho, where 65% of annual
precipitation occurs during the six-month (Sept. 1 to Feb. 28) winter period
and 30% during the four-month (March 1 to June 30) growing season. Stored
water is also important in the Eastern Idaho Plateau where the low annual
precipitation is nearly evenly distributed over the months of the year.
The water balance equation tells us that change in water content in the
soil - precipitation + inflow - runoff + upward flow - drainage -
evapotranspiration (ET). Any cultural practice that decreases runoff or ET
can result in increased water in the soil. To store adequate quantities
of water, deep soils (> 60 inches) with good infiltration and water holding
capacity are required. Summer fallow has long been the traditional practice
for storing water in soils for later use by crops. Fallow periods vary from
14 to 15 months where winter small grains are seeded to 21 months where
spring small grains are seeded. Water storage efficiency for fallow is low,
ranging from 10 to 35% in the Great Plains and the Southwest; to 30-37% in
eastern Idaho and northern Utah; to 40-45% of precipitation in the Inland
Pacific Northwest (Evans and Lemon, 1957). Good water conservation yields
increased crop production, stability of production, and increased water use
efficiency. Soil tillage and residue management play significant roles in
collection and storage of precipitation in the soil.
Our objectives are to discuss insights in water conservation gained under
the STEEP (Solutions to Economic and Environmental Problems) program
(Oldenstadt et al., 1982) during these last ten years and problems that
remain. New research information will be discussed under topics of crop
residues, conservation tillage systems, fallow and models.

Item Type: Technical Bulletin
NWISRL Publication Number: 0628
Subjects: Soil > Tillage
Mass Import - autoclassified (may be erroneous)
Depositing User: Dan Stieneke
Date Deposited: 20 Nov 2010 21:58
Last Modified: 25 Oct 2016 18:13
Item ID: 1201