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Impact of Soil Aeration on RunoffCharacteristics in Dual Purpose No-
Till Wheat SystemsPaul DeLaune
Texas A&M AgriLife Research - Vernon
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6 million wheat acres managed asdual purpose in Texas, Oklahoma,and New Mexico (Taylor, 2010).
Southern Great Plains: 5% No-till 80% Conventional Till
No-till adoption in graze and grainsystems lower than grain onlysystems
Dual Purpose Wheat Systems (graze and gain)
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Grazing can:
Increase soil compactionIncrease the potential for soil erosion
Decrease water infiltrationIncrease Runoff (71% vs 12% of received precip.)Increase losses of N and P via runoff
Texas High PlainsGrazing no-till reduced soil water storage and depressedwheat and sorghum yields.
Grazing and Compaction
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Does grazing no-till wheat result in increased compaction,decreased infiltration, increased runoff?
Should long-term no-till wheat be tilled to alleviatecompaction concerns?
Evaluate the impact of tillage, specifically soil aeration, on
long-term no-till dual-purpose wheat systems on runoff waterquantity and quality.
Questions/Objective
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AerWay
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0 o 2.5 o5 o
7.5 o 10o
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Smith-Walker Research Unit near Vernon
Tillage Systems Conventional Till (disking)
No-Till Aeration at roller angles of:
0, 5, and 10 degrees
Grazing System Graze and Grain Graze out
Materials & Methods
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Clay loam soilConverted to no-till wheat in 2001Study took place 2009-2011
Grazing2009-2010 Graze/Grain = Jan 15 to March 1 (11,454 lb ac -1) Graze Out = Jan 15 to April 30 (26,172 lb ac -1)
2010-2011 Graze/Grain = Drought, no grazing Graze Out = March 15 to April 30 (54,000 lb ac -1)
Site History and Grazing
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7 cm hr -1
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Tillage treatments implemented September each yearRunoff events occurred:
Oct 2009 6 wks after tillage, 30 N, 10 P 5 wks prior
June 2010 after wheat harvest, midseason N -18 lb
Sept 2010 20 days after tillage, immediately after N&P (18 lb)
June 2011 after wheat harvest, midseason N -27 lb
Tillage and Rainfall Timing
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Date of simulated rainfall
Oct 2009 Jun 2010 Sep 2010 June 2011
Runoffvolume(L)
0
20
40
60
800
o
Roller Angle5 o Roller Angle10 o Roller AngleNo-tillConventional till
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Date of Simulated Rainfall
Oct 2009 Jun 2010 Sep 2010 June 2011
Infiltration (cm)
0
2
4
6
80510NTCT
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Date of simulated rainfall
Oct 2009 Jun 2010 Sep 2010 June 2011
Runoffvolume(L)
0
20
40
60
80Graze outGraze/Grain
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Date of Simulated Rainfall
Oct 2009 Jun 2010 Sep 2010 June 2011
Infiltration (cm)
01
2
3
4
5
6
7Graze OutGraze/Grain
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Date of simulated rainfall
Oct 2009 Jun 2010 Sep 2010 June 2011
Total P(mgL
-1)
02
4
6
8
10
12
14
16
0% Roller angle5% Roller angle10% Roller angleNo tillageConventional tillage
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Date of simulated rainfall
Oct 2009 Jun 2010 Sep 2010 June 2011
NO
3(m
g L
-1)
0
1
2
3
4
0% Roller angle5% Roller angle10% Roller angleNo tillageConventional tillage
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Date of simulated rainfall
Oct 2009 Jun 2010 Sep 2010 June 2011
Total P (mg L
-1)
0
2
4
6
8
10
12
14
Graze outGraze/Grain
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Date of simulated rainfall
Oct 2009 Jun 2010 Sep 2010 June 2011
NO
3(mg L
-1)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Graze outGraze/Grain
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Tillage and grazing did not significantly affect bulk density.
Aeration was most effective in reducing runoff and nutrient losseswhen storm event occurred within 20 days of implementation, nolonger effective at 6 weeks.
Graze out plots had higher runoff rates, higher nutrient losses,and lower infiltration rates than graze and grain system.
Overall, tilling of no-till wheat had a short term effect on runoffcharacteristics and not all tillage treatments improved thesecharacteristics compared to no-till.
No-till can increase infiltration and withstand the effects of proper
grazing intensities compared with mechanical aeration anddisking.
Economic considerations must also be taken into account prior totilling no-till wheat systems.
Conclusions
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Appreciation to Texas WheatProducers Board for project
support
Questions?
Paul DeLauneProject Lead940-552-9941 x207
