1. Influence of Crop Rotation and Tillage on Soil Physical Properties in Southwest Oklahoma
Silvano L. Abreu1, Chad B. Godsey1, Gary Strickland2, and Jeff T. Edwards1
1Department of Plant and Soil Sciences, Oklahoma State University. 368 Ag Hall, Stillwater, OK, Southwest Research and Extension Center. Altus, OK.
Introduction
Adoption of no-till in Southwest Oklahoma has been slow. The lack of crop rotation has reduced the success of producers who have tried no-till. Monoculture winter wheat is the dominant cropping system of the area.
The present study was established in the fall of 2002 to gather data on dryland no-till cropping systems to help address producers’ questions.
The objective of the present work is to evaluate soil physical (aggregate stability and soil strength) properties, organic carbon and total nitrogen under different crop rotation and two tillage practices in southwest Oklahoma
Soil Analysis
Water aggregate stability from 0 to 10cm depth.
Soil resistance using hydraulic cone penetrometer
Soil Organic carbon (SOC) (loss on ignition) in the depths of 0 to 10, 10 to 20, 20 to 40, and 40 to 70cm (data not presented)
Total Nitrogen (TN) (Leco) on the same depths of organic carbon (data not presented)
Results
Figure 2. Aggregate stability - sum of 3 classes (A) and GMD (B) - of soils under different crop rotations and tillage practices in southwest Oklahoma. Altus, OK, 2008.
Material and Methods
Local: Southwest Research and Extension Center, Altus, OK
Soil: fine, mixed, superactive, thermic Vertic Paleustolls
Treatments
Tillage
No-tillage
Conventional tillage
Rotations
C-W-GS: Cotton – Wheat – Grain Sorghum
C-W: Cotton – Wheat
C-GS: Cotton – Grain Sorghum
W-DCGS-C: Wheat – Double Crop Grain Sorghum – Cotton
C: Cotton Mono-crop
W: Wheat as Mono-crop
GS: Grain Sorghum as Mono-crop
Discussions
Soils under conventional till have higher penetration resistance then no-till for all rotations
Rotations cotton-wheat and continuous wheat have lower effect in reducing soil penetration resistance
Overall no-till treatments have more stable aggregates and higher GMD compared to conventional till
No-till SOC in the upper 70cm is 1.12 times higher than conventional till, however no differences in TN is observed (data not presented)
Overall, all soil depth evaluated present higher SOC in no-till compared to conventional till. Higher differences are observed in the upper 20 cm of the soil profile (data not presented)
Significance level for rotation/tillage comparisons:NS = non significant;* = 0.05; ** = 0.01; *** =
Figure 1. Soil strength under different crop rotation, conventional and no-till in southwest Oklahoma. Altus, OK, 2008.