Effects of shallow non-inversion tillage on sandy loam soil properties and winter rye yield in organic farming

Due to an expected improvement of soil quality and soil water storage, the substitution of mouldboard ploughing by reduced tillage was identified as a potential climate change adaptation measure for organic farming in a relatively dry region with a humid continental climate. In a field trial on a sandy loam soil in eastern Germany, reduced tillage was carried out to 6 cm soil depth by means of a ring cutter and compared to mouldboard ploughing with 25 cm tillage depth. In the present study, the influence of ring cutter tillage on soil properties was investigated for the first time. The effects of shallow ring cutter tillage on soil physical parameters, soil organic matter distribution, soil mineral nitrogen content, total nitrogen uptake by the crop, root content, and grain yield of organically grown winter rye (Secale cereale L.) were analysed in the uppermost 20 cm of a sandy loam soil and compared to those of mouldboard ploughing. Under ring cutter tillage, soil bulk density was in 8-20 cm soil depth by up to 15% higher than under mouldboard ploughing. In 9-15 cm soil depth, ring cutter tillage resulted in smaller contents of coarse macropores and mesopores, more micropores, and an 11% smaller available water capacity compared to mouldboard ploughing. The total nitrogen uptake by winter rye was in the ring cutter treatment by up to 44% smaller than in the mouldboard plough treatment. Root content was up to 209% higher in 1-6 cm soil depth and up to 71% smaller in 8-20 cm soil depth after ring cutter tillage than after mouldboard ploughing. Winter rye yield declined by 22-43% in the ring cutter treatment relative to the mouldboard plough treatment. Shallow ring cutter tillage resulted in a root growth-restricting soil compaction in the non-tilled soil layers below 6 cm depth and led to a limitation of nitrogen mineralisation until spring. Both effects likely caused the considerable reduction of crop yield. The results suggest that shallow ring cutter tillage in organic farming seems to be not suitable for sandy loam soils as long as the risk of a soil compaction-induced limitation of root growth and nitrogen supply cannot be minimised.

Automated summary

This study investigated the potential climate change adaptation measure of reduced tillage for organic farming in a relatively dry region. The results showed that shallow ring cutter tillage on sandy loam soil led to increased soil bulk density, decreased available water capacity, and reduced crop yield.