Residual effects of a slant-legged subsoiler on shoot growth and grain yield of spring barley

Abstract

SummaryIn a long-term cultivation experiment comparing mouldboard ploughing, shallow cultivation and direct drilling, soil compaction was identified as a problem. Root growth was restricted and this possibly caused a decline in grain yield of spring barley. The residual effects of a slant-legged subsoiler (Trade name, ‘Paraplow’) on the growth and yield of spring barley up to 34 months after its use were measured.In 1982, soil not loosened with the ‘Paraplow’ had a grain yield of 5·16 t/ha and cultivation with the ‘Paraplow’ either 22 or II months previously had a negligible effect. Although the implement improved mean plant establishment by up to 12 plants/m2, compensatory tillering occurred in the treatments that initially had fewer plants, thus reducing differences in dry-matter production and grain yield at harvest. The long-term system of cultivation had a larger effect on grain yield than the ‘Paraplow’ did. Grain production on direct-drilled and shallow cultivated soils exceeded that after mouldboard ploughing by up to 0·55 t/ha (P < 0·05). The ‘Paraplow’ used 22 months previously increased grain yield by 0·47 t/ha on a direct-drilled soil that had become compacted.In 1983, the emergence of seedlings was low (54%) due to waterlogging of the seed bed between germination and emergence. The ‘Paraplow’ used 8 months previously increased the mean number of plants that emerged by 20 plants/m2. More seedlings survived on the soil loosened by the ‘Paraplow’ because it drained more freely than the undisturbed soil. Cultivating with the ‘Paraplow’ 11, 23 and 34 months previously increased grain yield by 0·27, 0·29 and 0·13 t/ha respectively, but the mean grain yield was only 2·70 t/ha. This improvement was caused by a greater number of grains per m2 on the soils loosened with the ‘Paraplow’. Grain weight was unaffected by cultivation system or by ‘Paraplow’ treatment.