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Effect of R&R Subsoiler vs. Uphill Plowing on Following Season
Erosion Control and Crop Production

David Ostheller
with Harry Riehle, Dave Welk, Steve Sprecher, LeRoy Riehle and Shawn Woodard, NRCS;
Stewart Wuest, McGregor Co.; Don McCool, WSU;
and Lawrence Brown and Paul Peterson, Spokane Co.

Objective

Determine the effect of using the R&R subsoiler compared with uphill plowing on subsequent season erosion and crop yield.

• Location: Fairfield, WA (SE Spokane Co.: NE 1/4, S2-T21-R45)
• Annual precipitation: 21 inches
• Soil series: Naff silt loam
• Rotation:
  • 95 - winter wheat
  • 94 - lentils
  • 93 - winter wheat
  • 92 - lentils

Treatments

The treatment area included both north and south slopes across a ridge. Wheat was harvested in the fall of 1993 and plots were laid out in strips up and down the slope and across the ridge top and each strip was either uphill plowed or subsoiled with an R&R subsoiler. The four replicates were applied alternately rather than randomly. The plot area was seeded to lentils in 1994 and back to wheat in the fall of 1994. The lentil ground was chiseled and fertilized with aqua in one pass. The ground was seeded cross slope. Voided rill measurements were collected at the end of the erosion season.

Comments

The roughness and residue in both treatments was essentially the same after winter was seeded a year after the treatment application, and the erosion measurements were so variable no difference can be established, even though the plowed plots produced higher erosion in three of the plot pairs.

Data

Plot characteristics and soil erosion one year after using R&R subsoiler vs uphill plowing

	Slope length & steepness
	N		S
Treatment	ft	%	ft	%	Surface residue %	Surface roughness RB in	Plant cover %	Erosion T ac-1
Plow	120	15	100	8	37	0.30	8	6.75
R&R	120	15	100	8	42	0.30	7	1.25
Plow	120	15	100	8	42	0.30	7	4
R&R	120	15	100	8	42	0.30	7	<1
R&R	120	8	100	8	39	0.30	7	<1
Plow	120	8	100	4	39	0.30	7	<1
R&R	120	8	100	4	39	0.30	7	<1
Plow	120	8	100	4	39	0.30	7	0.75

R&R subsoiler vs uphill plowing for yield (bu/ac)

Treatment	Rep 1	Rep 2	Rep 3	Rep 4	Average
Plow	81.4	76.2	75.7	73.7	76.8a
R&R	78.1	80	73.6	78.2	77.5a
CV					3.66%

Not significant at 20%

Conclusion

No statistical difference in soil erosion on seeded winter wheat was observed one year after using an R&R subsoiler vs. uphill plowing; nor were yields significantly different. moisture content was similar at seeding although the summer was much dryer. The need for additional trials with both wheat and barley is indicated.

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Hans Kok, WSU/UI Extension Conservation Tillage Specialist, UI Ag Science 231, PO Box 442339, Moscow, ID 83844 USA Redesigned by Leila Styer, CAHE Computer Resource Unit; Maintained by Debbie Marsh, Dept. of Crop & Soil Sciences, WSU