Soil available P and P offtake responses to different tillage and fertilisation systems in the hilly morainic landscape of western Lithuania

Landscape position may be an important determinant of soil P availability and cereal response to P fertilisation, especially under different tillage management systems. We determined soil P availability and P offtake responses to fertilisation under traditional deep ploughing and three reduced tillage systems on sloping Alboluvisol in Lithuania during 1995–1998. Moderate rates of fertiliser significantly increased crop yield and P offtake with all tillage systems at all landscape positions, but ploughing gave 9–15% less P offtake than did any of the reduced tillage systems. Application of a high rate of fertiliser improved overall yield and P offtake further at summit and slope positions, but not at the foot position. More pronounced increases in soil P content occurred at 10–20 cm soil depth than at 0–10 cm soil depth, irrespective of tillage system. On a slope where traditional deep ploughing is replaced by chiselling or other reduced tillage systems, it appears to be necessary to apply a high rate of P fertiliser to increase soil P. On sloping morainic agricultural land, ploughing could be successfully replaced by reduced tillage systems that include glyphosate application.