Download Conservation Tillage Systems and Liming Materials

Conservation Tillage Systems and Liming Materials
Report for Third Year (2004)
Gene Stevens and David Dunn
The adoption of conservation tillage systems continues to increase across
Missouri. However, no-till and strip-till farmers have expressed concern that lime may
need to be incorporated with conventional tillage equipment to neutralize soil acidity
below the 0 to 2-inch soil depth. Research at the University of Tennessee Milan
Experiment Station showed that surface applied lime on a no-till field effectively
increased soil pH in the soil profile. However, this study was conducted on a loessial silt
loam soil with good internal drainage. Whether the same would be true on a poorly
drained Sharkey clay soil is not known. Solubility of the liming material may also be a
factor. Tests with conventional till cotton at the University of Missouri Delta Center
showed that dolomitic lime increased soil pH slower than calcitic lime, but both types of
lime resulted in the same amount of cotton yield increase. A study was begun in 2002 to
determine the soil depth that surface applied lime in conservation tillage systems will
neutralize soil acidity on clay and silt loam soils.
Research activities in 2004:
Tests were conducted at four locations. Fields on the University of MissouriDelta Center with Dubbs silt loam (average initial pH salt 5.2) and Tiptonville silt loam
soils (average pH salt 5.3) were used. Two fields with Sharkey clay soil (average initial pH
salt 4.6) at the University of Missouri Lee Farm were also used. A corn-soybean rotation
system was used at the silt loam and clay sites. A split-plot design was used with no-till,
strip-till and conventional till main plots. Soil pHsalt and Woodruff buffer pH were used
to determine the recommended amount of ENM needed to raise the pH to the 6.1 to 6.5
range. Liming materials were obtained from local dealers and tested for ENM value.
Sub-plot treatments were the recommended rate of calcitic (white) lime, recommended
rate of dolomitic (red) lime, and an untreated check. Liming materials were applied in the
April 2002 on the silt loam sites and April 2003 on the clay sites. These were surface
applied before any tillage was done. In September or October each year, soil cores were
collected from the 0 to 6-inch soil depth. The cores were cut into 2-inch increments (0 to
2-inch, 2 to 4-inch, and 4 to 6-inch soil depths) and tested for soil pH and extractable Mn.
Plots will be mechanically harvested for yield.
Conclusion
We found no consistent soil pH or yield results indicating tillage is needed to
incorporated lime in soybean or cornfields (Tables 1 and 2 ). Yield response to liming
materials was generally positive but no always statistically significant compared to the
untreated check. Soil tests from the 0 to 6-inch depth showed that dolomitic and calcitic
lime both increased soil pH and reduced extractable Mn levels (Figures 1 and 2). Low
soil pH increases Mn and Al availability (toxic at high levels) and decreases the
availability of important nutrients like P. Although Mn is an essential element, Mn
toxicity is more common in Missouri than Mn deficiency.
We will continue the experiment on the Sharkey clay soil in 2005 without funding
to gain more results and publish the information from both soils in a scientific journal.
Table 1. Effect of lime material on soybeans and corn at the MU Delta Center Marsh
Farm averaged from 2002 to 2004 on a Reelfoot sandy loam soil with initial soil pHsalt of
5.2.
Tillage
Lime
No tillage
Dolomitic
Calcitic
Check
Dolomitic
Calcitic
Check
Dolomitic
Calcitic
Check
Strip tillage
Conventional
Grain yield †
Corn
Soybean
-----bu/acre---123 a
59 a
107 b
58 a
103 b
56 a
115 a
55 a
123 a
54 a
108 a
56 a
110 a
56 a
123 a
51 b
114 a
50 b
† Within a tillage system, yields followed by the same letter were non-significant at 0.05 level.
Table 2. Effect of lime material and tillage on soybeans and corn at the MU Delta Center
Lee Farm in 2003 and 2004 on Sharkey clay with initial soil pHsalt of 4.6.
Tillage
Lime
No tillage
Dolomitic
Calcitic
Check
Dolomitic
Calcitic
Check
Dolomitic
Calcitic
Check
Strip tillage
Conventional
Grain yield †
Corn
Soybean
-----bu/acre---96 a
38 a
82 a
41 a
78 a
43 a
105 a
41 ab
78 ab
43 a
67 b
37 b
79 ab
37 a
101 a
37 a
70 b
32 a
† Within a tillage system, yields followed by the same letter were non-significant at 0.05 level.
Tiptonville Silt Loam
Extractable Mn, lb/acre
Soil pH (salt)
4.0
5.0
6.0
0
7.0
0
10
15
20
25
Calcitic
Dolomitic
Check
Dolomitic
Calcitic
Soil Depth (inches)
Soil Depth (inches)
5
0
2
4
Check
2
4
6
6
Figure 1. Conventional tillage soil pHsalt and Mn levels in the surface 0 to 6-inch soil
layer in 2004.
Extractable Mn, lb/acre
Soil pH (salt)
4.0
5.0
6.0
0
7.0
4
6
Dolomitic
Calcitic
Calcitic
10
15
20
25
Dolomitic
Check
Soil Depth (inches)
Soil Depth (inches)
Check
2
5
0
0
2
4
6
Figure 2. No-tillage soil pHsalt and Mn levels in the surface 0 to 6-inch soil layer in 2004.