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Djupplöjning på lätta mineraljordar

Rydberg, Tomas; McAfee, Mary; Gillberg, Börje

Sammanfattning

The effect of a single deep ploughing to 35 and 50 cm depth on subsequent crop yields on sandy soil was investigated in a series of 5-6 year experiments on 14 Swedish sites. Root depth was restricted to the topsoil on all sites prior to treatments, and the sand type was coarse (0.6-2.0 mm) on 1 site, medium (0.2-0.6 mm) on 7 sites and fine (0.06- 0.2 mm) on the remaining 6 sites (Table 1). The effect of an additional 30 kg N/ha fertilizer was investigated as a secondary treatment. Ploughing to 35 cm depth improved yields relative to the normal ploughed control by on average 4% (Table 6). However, this positive effect was greatest in years 1-3 and had disappeared within 5 years. Ploughing to 50 cm depth had on the whole no or a somewhat negative effect compared to normal ploughing (Table 7). Positive results were obtained on the coarser sands, and on all sands in dry years. In wet years, however, there were indications of aeration problems in the ploughed-in topsoil on fine sands. Root studies showed that rooting depth was on average 5-15 cm greater on soil which had been ploughed to 50 cm. Where positive effects were obtained, they were obviously due to increased water availability to the crop. The negative effects observed were probably due to aeration problems on fine sands and more particularly to soil recompaction during secondary tillage after the deep ploughing treatment. The reduction in organic matter content of the topsoil due to its mixing with the subsoil was likely to have increased the sensitivity to compaction of these sandy soils. The application of an extra 30 kg N/ha improved yields by 6-7% at all 3 ploughing depths investigated. Thus there was no additional advantage in fertilizing deep-ploughed plots despite the fact that nutrient availability was somewhat lower on these (Table 4). There was a difference between crops in their response to deep ploughing. Oats showed a positive yield response of 12%, while potatoes showed a negative yield response of 10% (Fig. 3). The effect of incorporating 500 m3/ha raw bark into the topsoil after ploughing to 50 cm was investigated on one site (Vinberga). After an initial year of very low yield, this treatment gave a large positive effects on yield, presumably as a result of improved soil structure. It was concluded from this series of experiments that deep ploughing was not an economically justifiable soil improvement treatment, since better and more consistent results could be obtained by fertilizing combined with normal ploughing. In very dry areas or on coarse sands water availability could be improved more reliably by irrigating than by deep ploughing

Nyckelord

jordbearbetning; djupplöjning; mineraljord; skördeökning; rotstudier; vattentillgång; mullhalt; återpackning; kvävegiva

Publicerad i

Rapporter från Jordbearbetningsavdelningen, Sveriges lantbruksuniversitet
1990, nummer: 80ISBN: 91-576-4178-1
Utgivare: Institutionen för markvetenskap, Jordbearbetningsavdelningen, Sveriges lantbruksuniversitet

      SLU författare

    • Rydberg, Tomas

      • Institutionen för markvetenskap, Sveriges lantbruksuniversitet

    UKÄ forskningsämne

    Jordbruksvetenskap

    Permanent länk till denna sida (URI)

    https://res.slu.se/id/publ/30282