The influence of different tillage systems on the nutritional status of sugar beet plants

Long-term minimum tillage alters the soil nutrient status compared to mouldboard Ploughing. Thereby it may affect the nutritional status of crops. This hypothesis was tested in a field trial with significantly lowered yields after long-term firm soil mulch husbandry (FBMW) compared to loose soil husbandry (LBW) in sugar beet (preceding crop barley, 4 levels of N fertilisation). After FBMW plant available nutrients K, P, Mg were enriched in the topsoil layer and had become poorer in the medium and deeper horizons (10 to 45 cm) compared to the LBW treatment. Total amounts in the 0 to 45 cm layer were very similar. In the leaves, nutrient concentrations differed between tillage treatments as follows: a) 0 kg N ha(-1): N: FBMW<LBW, P: FBMWgreater than or equal toLBW, K: FBMW>LBW, Mg: FBMW: LBW; b) 170 kg N ha(-1): N: FBMWcongruent toLBW, P: FBMWless than or equal toLBW, K: FBMWmuch greater thanLBW, Mg: FBMW<LBW. Our results indicate that the yield decrease observed with FBMW compared to LBW is not caused by a limited soil nutrient supply or nutrient acquisition by the crop, except for N with zero N fertilisation. It is assumed, that yields decrease mainly due to higher soil strength, impeding fibrous root and beet growth.