SOIL SCI. SOC. AM. 3., VOL. 50, 1986
<br />trenches to within 0.23, 0.46, and 0.69 m of the
<br />Topsoil (from the native William¢ loam) was then placed i
<br />longitudinal strips on all trenches at thicknesses of 0.23, O. -
<br />and 0.69 m to give a uniform final soil surface, each to
<br />thickness occupying one -third the width of the trench.
<br />were used to fill and compact the
<br />in one trench for each spoil and subsoil treatment. Spoilvraa
<br />replaced in the other trench of each spoil and subsoil, =
<br />ment with front end loaders without compaction to sim
<br />conditions created by a draghne, and to give a relay►
<br />noncompacted condition_ Topsoil treatments at each
<br />subdivided into two replic each of which
<br />further subdivided, into three fertility a 1
<br />treatments were annual braodcast app Fertility ilia
<br />were 0 kg N ha - ' and 0 kg P ha -i ;, 34 kg hal, and )4
<br />P ha -1 , and 67 kg N nd 45 ha - �, designatedihe
<br />low, medium, and high fertility, vel Plots with
<br />fertility treatments on undisturbed land nearby were
<br />_
<br />fished to compare with yields from'•the declaimed
<br />Pl ots. , ,,.,_•,.. _:, 4 .::,r 9 {. -,
<br />`Olaf . wheat (Triticum aestivum - ) was growls ins
<br />METHODS AND MATERIALS `Park' barley (Hordeum vulgare L) in 1980, corn, (Zed
<br />L. cv. Agsco' 3x75)' in 1981; `Lew' -wheat m 1982, and
<br />A site was selected in west - central North Dakota near Un- ( Pioneer 3978) in 1983. Grain and silage samples
<br />derwood. The native soil was a Williams loam (fine - loamy, dried at 60 °C: Silage yields are reported at 700 g kg
<br />mixed Typic Argiborolls), developed on glacial till. Average content, corn grain yields - al 150 g kg and wheat and
<br />annual precipitation is 0.42 m, most of which falls in the ley yields at oven -dry weights; Yields were harvested
<br />spring and summer. each subsubplot from an area 3.3 m for wheat and bars •
<br />t each 16-m wide, -m rig, d from
<br />Eight trenches were excavated, 58 to , to 11- m 0.76 -m a
<br />, 1 ,,n8 pmt
<br />- ieatine o1
<br />420
<br />0.61 m of loamy sand topsoil. Doll et al. (1984) at-
<br />tributed this lack of response to thicker topsoil re-
<br />placement to the droughty nature of the replaced top-
<br />soil. On moderately sodic spoil (SAR = 11), yields on
<br />plots covered with 0.30 m of sandy loam topsoil were
<br />equivalent to yields from plots with 0.60 m of sandy
<br />loam topsoil (Pole et al., 1979).
<br />Concurrent with the initiation of mining north and
<br />east of the Missouri River in North Dakota, experi-
<br />ments were undertaken to determine topsoil and sub-
<br />soil thickness requirements of nonsaline, nonsodic
<br />spoil material. Treatments were incorporated into these
<br />experiments to determine how N and P fertilizer, and
<br />spoil compaction affected yields on topsoil and sub-
<br />soil /spoil variables. Supplemental water was added to
<br />selected plots in 1982 and 1983 to examine crop re-
<br />sponses to irrigation. The effects of spoil compaction
<br />will be discussed in another publication.
<br />(Bower and Wilcox, 1965) and soluble Ca, Mg, and Na con
<br />centrations were determined quantitatively using atomic ab-
<br />sorption spectrophotometry. The Na bicarbonate method
<br />(Knudsen, 1980) was used to determine P levels in the top-
<br />soil and available K was determined from om NH: acetate ex-
<br />tracts (Carson, 1980).
<br />Two trenches were filled with loamy sand spoil, two with
<br />clay loam spoil, and two with silty clay loam spoil to within
<br />0.23, 0.46, and 0.69 m of the surface. Two additional trenches
<br />were filled with loamy sand spoil to within 1.5 m of the
<br />- surface (Fig. 1). Clay loam subsoil, removed from the
<br />trenches, was placed on the loamy sand spoil in these two
<br />Fig. 1. Cross - section of trench showing placement of topsoil, subsoil,
<br />and spoil.
<br />soil and fertihty treatments is subplots an
<br />spectively. Yields from the irrigatedplots in 1982 kn su b s ub pIa it -
<br />were dropped f�r'oont - the > an�i°
<br />a1Yf varfance the no
<br />gated trencli'piot"' afa idwere- yzed separatel
<br />split -block c t opsoil thickness a3 the main plots i
<br />tility as the subpiots.: The bidistarbed plots were'anal
<br />separately`as `a rand`om`riect:�Plete block: Tukey's
<br />estly significant difl'erence`(HSD) -test was.used to test"
<br />nificant differences between treatment means of. each
<br />ysis of variance. r i i 418' i a . • �,� ;:. , . _
<br />si2?i .3 3 115 t:4_ ;;V i 4f >c �r
<br />RESULTS AND DISCUSSION
<br />Thickness , topso ; significantly incr re ..
<br />except for barley grain .yields in .1980 and corn_ silage
<br />Table 1. Chemical and phisicel chars
<br />cteriatics of soil and
<br />used in the trench plot's. _ ;
<br />: Gravelly
<br />loamy Clay
<br />Topsoil 'Subsoil r - sand loam t
<br />Sand, off, 86 84 - : - 78 40 ,-
<br />Silt, % 48 34 ; 13 - 31 49
<br />Clay, % - - 26 , 32 - 9
<br />Soil -water content at 0.17 0.19 0.08 0.19
<br />- 1.5MPa,m'm' . 1.4
<br />7.0
<br />10.1 r•
<br />7.5
<br />2.7 -
<br />� - -�
<br />and 4.6 -m deep, then filled with one of three different tax Z orn. lgg2 and¢ 1483 th high Ong a trickly+
<br />tures of spoil. Physical and chemical characteristics of the noncompacted tea e s we i$a�.
<br />materials are described in Table 1. Particle size distribution , , i ' gowingOn,theSe plots
<br />h ter . late June - and
<br />SAR -
<br />Soluble Na, mmol L"
<br />Soluble Ca, mmol
<br />Soluble Mg, mmol
<br />PH
<br />EC, dSm'
<br />P, kg ha"'
<br />K. kg ha - '
<br />MI
<br />of spoil, topsoil, and subsoil was determined using the y- l ives �fi n=igaioi ter _ . -
<br />drometer method (Day, Pa 1965). W content at -1 5 M - July , and the - grovvine n �iTiee pl s m 4983.
<br />was determined using pressure membrane apparatus (Rich- 152 bind mm of irrigation u► Iu an . ugu " -s = `
<br />ands, 1965). A glass electrode was used to measure pH (Peach, .. Yield data fr the.P9n Wi nch plots were a
<br />1965). Soluble salts were determined on saturation extracts do " . t ,., . -
<br />;t lit hlock with the su
<br />as a no_nran
<br />spoil by compactions tri4tmsnts as whole plots and _`�_h.
<br />.
<br />0.8 a 1.1 . 1.3
<br />,
<br />0.7 2.0 2.8
<br />3.0 , . 1.1 - 1.0
<br />1.9 2.4 3.7
<br />7.4 7.5 " - 7.7
<br />0.9 0.7 1.0
<br />12
<br />399
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