Effect of time of autumn primary tillage on soil structure, grain yield and risk of nitrogen leaching in two Swedish clay soils

Abstract

Delaying tillage and incorporation of arable crop residues in autumn may limit accumulation of soil mineral nitrogen (SMN) and reduce nitrogen (N) leaching. However, on clay soils, high water content during late tillage can impair soil structure and fertility. This study investigated the effects of tillage timing on SMN (0-90 cm depth), soil physical properties in the topsoil and yield in two Swedish clay soils differing in clay content. SMN generally increased during autumn and also with earlier tillage. On a heavy clay soil (Ultuna; approximate to 60% clay), SMN increased throughout winter until spring and the amount of N leached was probably small. In contrast, on a clay loam soil in southernmost Sweden (Rydsgard; approximate to 35% clay), SMN decreased during winter by up to 26 kg ha(-1). In general, measured soil water content (w) was lower than 0.9 x plastic limit (PL) at the time of early tillage (mouldboard ploughing or stubble cultivation), while it exceeded 0.9 PL at the time of normal and late tillage. The proportion of small aggregates produced by tillage was negatively correlated to relative soil water content at the time of tillage (w/PL). Conventional methods to determine soil physical qualities (bulk density, saturated hydraulic conductivity, aggregate tensile strength) did not show any clear differences between treatments. However, plant emergence and yield were significantly reduced after late compared with early tillage at Ultuna, a trend that has persisted from 2000 until the present. These results suggest that the suitability of delayed autumn tillage as a means to reduce SMN accumulation and N leaching varies between Swedish clay soils. A reduction in N leaching can be achieved on lighter clay soils in warmer and moister areas, whereas the effects may be small on heavier clay soils in central Sweden, where repeated late tillage carries a risk of yield reduction.

Keywords

clay soil; soil mineral nitrogen; soil structure; risk for nitrogen leaching; timing of tillage

Published in

Acta Agriculturae Scandinavica, Section B - Soil and Plant Science
2014, volume: 64, number: 1, pages: 33-44
Publisher: TAYLOR & FRANCIS AS

SLU Authors

• Myrbeck, Åsa

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

• Arvidsson, Johan

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

• Keller, Thomas

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    
  • Agroscope

UKÄ Subject classification

Soil Science

Publication identifier

• DOI: https://doi.org/10.1080/09064710.2014.882402

Permanent link to this page (URI)

https://res.slu.se/id/publ/61941