Soil & Tillage Research 71 (2003) 33–47
Soil water and nitrogen dynamics in dryland cropping systems
of Washington State, USA
Juan P. Fuentes
, Markus Flury
, David R. Huggins
, David F. Bezdicek
Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164, USA
USDA-ARS Land Management and Water Conservation Research Unit, Pullman, WA 99164, USA
Received 22 October 2001; received in revised form 10 October 2002; accepted 12 December 2002
Understanding the fate of soil water and nitrogen (N) is essential for improving crop yield and optimizing the management
of water and N in dryland cropping systems. The objective of this study was to evaluate how conventional (CT) and no-till
(NT) cropping systems affect soil water and N dynamics. Soil water and N were monitored in 30 cm increments to a depth of
1.5 m for 2 years at growers’ ﬁelds in two different agroclimatic zones of Washington State (USA): (1) the annual cropping
region with a mean annual precipitation of more than 500 mm (Palouse site) and (2) the grain-fallow cropping region with
mean precipitation below 350 mm (Touchet site). In each zone, a CT and a NT cropping system were chosen. All sites had an
annual cropping system, except for the CT site in the drier area, which was under a traditional winter wheat/fallow rotation
previous to the study. At Palouse, the volumetric water content in the top 1.5 m of the soil throughout the year was about
less under CT as compared to NT, indicating improved seasonal accumulation and distribution of soil water
under NT. Cropping systems modeling indicated, that during winter, surface runoff occurred in the CT system, but not under
NT. The differences in soil water dynamics between CT and NT were mainly caused by differences in surface residues.
Dynamics of NO
-N at Palouse were similar for NT and CT. At Touchet, differences in soil moisture between NT and CT
were less than 0.05 m
. Under NT, high levels of NO
-N, up to 92 kg NO
, were found after harvest below the
root zone between 1.5 and 2.5 m, and were attributed to inefﬁcient use or over-application of fertilizer. In both climatic zones,
grain yield was positively correlated with evapotranspiration.
© 2003 Elsevier Science B.V. All rights reserved.
Keywords: Soil water storage; Tillage methods; Water conservation; Water-use efﬁciency
Dryland crop production relies to a large extent on
water conservation (Stoskopf, 1985). In the Paciﬁc
Northwest of the United States, which includes the
eastern part of the state of Washington (Fig. 1), optimal
conservation of water is the key for long-term farming
sustainability, and can be attained through tillage me-
Corresponding author. Fax: +1-509-335-8674.
E-mail address: ﬂury@mail.wsu.edu (M. Flury).
thods that maximize inﬁltration, soil water retention,
and minimize soil erosion (Papendick, 1996; Hammel,
1996). Tillage methods affect soil physical properties
and consequently directly inﬂuence soil water bal-
ance and crop growth. Conservation tillage, especially
no-till (NT), can minimize soil erosion and nutrient
losses (Shipitalo et al., 2000; Schillinger, 2001), in-
crease water storage (Unger et al., 1988; Malhi et al.,
2001), and reduce production costs (Uri, 2000).
Several factors contribute to water conservation
under NT. Surface crop residues contribute to water
0167-1987/03/$ – see front matter © 2003 Elsevier Science B.V. All rights reserved.