ARS | Publication request: Long-term Tillage Influences on Soil Physical Properties under Dryland Conditions in Northeastern Montana

Submitted to: Archives of Agronomy and Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 6, 2009
Publication Date: N/A

Interpretive Summary: Long-term tillage influences physical, chemical, and biological properties of the soil environment and thereby crop production and quality. We evaluated the effect of long-term (>20 yrs) tillage [no-till (NT), spring till (ST), and fall and spring till (FST)] under continuous spring wheat (Triticum aestivum L.) on soil penetration resistance (PR), bulk density ('b), gravimetric water content ('m) and saturated hydraulic conductivity (Ks) under dryland cropping systems in northeastern Montana, USA. Tillage frequency influences on these physical properties were evaluated on a Dooley sandy loam soil (fine-loamy, mixed Typic Argiborolls) in a randomized complete block design with four replications. Soil PR was measured using a digital penetrometer in 2.5-cm increments to a depth of 25 cm at three locations across each plot. Undisturbed soil cores were sampled at 0 to 5, 5 to 10, and 10 to 15 cm depths and were used to measure 'b, 'm, and particle size distribution. Soil PR was significantly greater in the NT than in ST and FST treatments at 0 to 10 cm depth, but was greater in FST than in NT and ST at a depth deeper than 10 cm. In all three treatments, soil PR generally increased to a depth of 10 to15 cm and then decreased beyond this depth. Long-term tillage reduced soil compaction in the surface (0 to 10 cm), but increased in the subsurface at a depth > 10 cm due to the traffic intensity induced by tillage mechanism. Soil 'b was not affected by tillage and averaged 1.59, 1.58, and 1.61 Mg m-3 for NT, ST, and FST, respectively. Similarly soil 'm was not influenced by tillage and generally decreased with increased intensity of soil manipulation and tillage frequency. Soil Ks at 15 to 20 cm depth generally decreased with increased tillage frequency. The results showed that soil 'b, 'm and Ks were minimally influenced by tillage intensity after 22 year of treatment imposition.

Technical Abstract: We evaluated the effect of long-term (>20 yrs) tillage [no-till (NT), spring till (ST), and fall and spring till (FST)] under continuous spring wheat on soil penetration resistance (PR), bulk density ('b), water content ('m) and saturated hydraulic conductivity (Ks) under dryland cropping systems. Soil PR was significantly greater in the NT than in ST and FST treatments at 0 to 10 cm depth, but was greater in FST than in NT and ST at a depth deeper than 10 cm. Soil PR generally increased to a depth of 10 to15 cm and then decreased beyond this depth. Long-term tillage reduced soil compaction in the surface (0 to 10 cm), but increased in the subsurface at a depth > 10 cm due to the traffic intensity induced by tillage mechanism. Soil 'b was not affected by tillage and averaged 1.59, 1.58, and 1.61 Mg m-3 for NT, ST, and FST, respectively. Similarly soil 'm was not influenced by tillage and generally decreased with increased intensity of soil manipulation and tillage frequency. Soil Ks generally decreased with increased tillage frequency. The results showed that soil 'b, 'm and Ks were minimally influenced by tillage intensity after 22 year of treatment imposition.