Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/29/2003
Publication Date: 3/1/2004
Citation: Blanco-Canqui, H., Gantzer, C.J., Anderson, S.H., Alberts, E.E. 2004. Tillage and crop influences on physical properties for an epiaqualf. Soil Science Society of America Journal. 68:567-576.
Interpretive Summary: The influence of tillage, particular no-till, on surface runoff losses appears to be climate and soil dependent. On many soils, no-till significantly reduces runoff due to macropores formed in the soil by worms and nightcrawlers. On the claypan soils of Missouri and Illinois, however, no-till increases average annual runoff by nearly 20%. The claypan subsoil, along with a shallow ground water table, provides an inhospitable environment for invertebrates that over-winter deep in the soil. The purpose of our study was to find a soil property that could be measured and easily related to surface runoff losses on these soils. Soil cores were collected in 1994 from long-term runoff plots in wheel tracks and in non- wheel track areas and used to measure saturated hydraulic conductivity (Ksat). Six treatments were initiated on the plots in 1983 including corn and soybeans with moldboard plowing, chisel plowing, and no-till. A seventh treatment was continuous cultivated fallow where no crop was grown and the soil was continuously tilled to control weeds. Ksat values were lower from trafficked areas than from non-trafficked areas, which was an expected finding. However, for soil in the corn and soybean plots that was not subjected to tractor and implement traffic, no significant differences in Ksat values were found. Therefore, Ksat was not a sensitive indicator of surface runoff losses from different tillage systems on claypan soils. Our results show that no-till does increase surface runoff which will be useful to producers and watershed managers interested in reducing non-point source pollution. Our results also show the difficulty in measuring one soil property to characterize surface runoff potential in the field, a useful finding to producers, crop consultants, and researchers.
Technical Abstract: Beneficial effects of conservation tillage on runoff and saturated hydraulic conductivity (Ksat) remain unclear. The objective of this study was to evaluate the influence of long-term tillage and cropping treatments on Ksat and surface runoff on a claypan soil (Aeric Vertic Epiaqualf). The Ksat was measured on undisturbed 76-mm diameter soil cores collected from long-term erosion plots located in north-central MO. Cropping and management treatments included corn (Zea mays L.) and soybean (Glycine max L.) under no-tillage (NT), moldboard plow (MP), and chisel plow (CP). Two additional plots were under continuous cultivated fallow (F). Samples were collected in 1994 from tracked and untracked inter-row positions at 0.05-m and 0.15-m depths. Precipitation and runoff records from 1983 through 1993 for the long-term site were studied. The F had the lowest Ksat (0.2 mm h**-1) attributed to soil structure deterioration and reduced macropores. Ksat was not different (P=0.59) among NT, MP, and CP treatments, but Ksat was higher (p=0.04) in the untracked position than in the tracked position. Annual runoff losses under F were always the highest of the seven treatments. Within each year, runoff was the highest in seasonal period 4 and the lowest in seasonal periods 1 and 2. NT had higher runoff losses than the MP and CP treatments in Period 4, spring (p=0.006), Period 4, fall (p=0.011), fallow period (p=0.005), and periods 1 and 2. NT cumulative runoff was higher than that with MP and CP (p=0.021), except from 1991 to 1993 (P=0.374). Correlation between runoff and Ksat was not significant (p=0.150; r=-0.20). The F had the highest Ksat and annual runoff whereas NT produced higher annual runoff than MP and CP in 7 of the 11 years.