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Research article - Peer-reviewed, 2012

Effects of autumn tillage of clay soil on mineral N content, spring cereal yield and soil structure over time

Myrbeck, Åsa; Stenberg, Maria; Arvidsson, Johan; Rydberg, Tomas

Abstract

Autumn tillage strategies designed to reduce leaching losses of nitrogen (N) from arable fields were examined on a medium clay soil (approx. 40% clay) in terms of their effects on accumulation of soil mineral N (SMN) during autumn and winter, crop N uptake, grain yield (spring-sown cereals) and soil structure over the long term (1997-2004). Tillage strategies included mouldboard ploughing (20-25 cm depth) and stubble cultivation (10-12 cm depth) in different combinations and timing, together with different options for straw management and catch crops. Postponing mouldboard ploughing from early September to early November significantly decreased SMN content during autumn and winter, although levels were generally low in all treatments. On average, the soil profile down to 90 cm depth contained 30 kg N ha(-1) in November and 27 kg N ha(-1) in December with early mouldboard ploughing, while the corresponding figures for late mouldboard ploughing were 16 and 21 kg N ha(-1). Stubble cultivation stimulated N mineralisation but the increase in SMN from tillage in September to November was only 3 kg ha(-1) after stubble cultivation, compared with 8 kg ha(-1) after mouldboard ploughing. Stubble cultivation before late mouldboard ploughing resulted in 6 kg ha(-1) higher SMN during autumn than late ploughing without preceding cultivation. Postponement of mouldboard ploughing significantly decreased grain yield by on average 11% and this negative effect accumulated over time. A catch crop compared with no catch crop reduced SMN during autumn and winter by 3-5 kg ha(-1) and had no significant yield effect. Effects of straw incorporation were small and could not be significantly proven either for SMN or yield. Transport of SMN to deeper layers was generally limited and SMN did not decrease during winter, indicating a minor impact of tillage time on N leaching risk. No significant changes in soil physical parameters were detected, but the results indicated poorer soil structure after tillage in late autumn compared with early autumn in terms of higher soil bulk density, lower aggregate stability in water, and lower infiltration rate. Overall, considering the short-term and long-term negative effects on yield and possibly soil structure, the benefit of delaying tillage seems small on this clay soil. (C) 2011 Elsevier B.V. All rights reserved.

Keywords

N leaching; Tillage; Clay; Soil compaction

Published in

European Journal of Agronomy
2012, Volume: 37, number: 1, pages: 96-104
Publisher: ELSEVIER SCIENCE BV