Soil tillage methods to control phosphorus loss and potential side-effects: a Scandinavian review

Abstract

In Scandinavia high losses of soil and particulate‐bound phosphorus (PP) have been shown to occur from tine‐cultivated and mouldboard‐ploughed soils in clay soil areas, especially in relatively warm, wet winters. The omission in the autumn of primary tillage (not ploughing) and the maintenance of a continuous crop cover are generally used to control soil erosion. In Norway, ploughing and shallow cultivation of sloping fields in spring instead of ploughing in autumn have been shown to reduce particle transport by up to 89% on highly erodible soils. Particle erosion from clay soils can be reduced by 79% by direct drilling in spring compared with autumn ploughing. Field experiments in Scandinavia with ploughless tillage of clay loams and clay soils compared to conventional autumn ploughing usually show reductions in total P losses of 10–80% by both surface and subsurface runoff (lateral movements to drains). However, the effects of not ploughing during the autumn on losses of dissolved reactive P (DRP) are frequently negative, since the DRP losses without ploughing compared to conventional ploughing have increased up to fourfold in field experiments. In addition, a comprehensive Norwegian field experiment at a site with high erosion risk has shown that the proportion of DRP compared to total P was twice as high in runoff water after direct drilling compared to ploughing. Therefore, erosion control measures should be further evaluated for fields with an erosion risk since reduction in PP losses may be low and DRP losses still high. Ploughless tillage systems have potential side‐effects, including an increased need for pesticides to control weeds [e.g. Elytrigia repens (L.) Desv. ex Nevski] and plant diseases (e.g. Fusarium spp.) harboured by crop residues on the soil surface. Overall, soil tillage systems should be appraised for their positive and negative environmental effects before they are widely used for all types of soil, management practice, climate and landscape.

Effects of soil erosion by water under different tillage treatments on distribution of soil chemical parameters

“…Gaynor and Findlay (1995) concluded that conservation tillage reduces average soil loss compared to conventional tillage. The same authors concluded that conservation tillage has effectively reduced soil erosion but also increased phosphorus loss, a finding in opposition to the results obtained by Ulen et al (2010). Hussain et al (1999) determined that soil pH and TOC were higher at NT compared to conventional tillage.…”

No-till in northern, western and south-western Europe: A review of problems and opportunities for crop production and the environment

“…In Scandinavia leaf net blotch (Pyrenophoros teres) has increased after no-till (Ulén et al 2010) but generally increased crop diseases have not been widespread with no-till. In Scotland fungus snow-rot (Typhula), which affects winter-sown cereals, was less prevalent after no-till than after ploughing (Ball and Davies, 1997).…”

A review of phosphorus and sediment release from Irish tillage soils, the methods used to quantify losses and the current state of mitigation practice

“…Conservation tillage in autumn may reduce losses of soil and PP by improving soil structure. In Norway, ploughing and shallow cultivation of sloping fi elds in spring instead of ploughing in autumn have been shown to reduce particle transport by up to 89% on highly erodible soils (Ulén et al 2010). Rational land-use policies, such as the promotion of 'set-aside' on erodible soils, the use of grass strips on erodible arable slopes and buffer strips in riparian zones, were identifi ed as mitigation options for reducing soil erosion by Fullen et al (2003).…”