Western Australia
May 16, 2016
On-row sowing may significantly benefit crop emergence during drier seeding conditions, although yield benefits have not yet been measured in Western Australian field trials.
This is the message from CSIRO researcher Margaret Roper who has led Grains Research and Development Corporation (GRDC) supported trials of on-row sowing, also involving the Department of Agriculture and Food (DAFWA).
On-row sowing is when crops are sown immediately alongside or within the previous crop row, compared with inter-row sowing in which crops are sown in between the old crop rows.
Most grain crops are sown mainly in the inter-row to avoid problems with the previous year’s residues wrapping around seeding boots. A high level of precision is required for on-row sowing.
Dr Roper said that in a 2015 trial at Pingrup, trials compared on-row and inter-row sowing in both dry sown (early - before rain) and wet sown (after rain) conditions.
“Under dry sown conditions, on-row seeding increased plant emergence to 158 plants per square metre compared with inter-row sowing (112 plants per square metre),” she said.
“The differences in seed placement did not translate into yield differences at the end of the season, probably due to favourable spring conditions.
However, regardless of sowing position, wet sown crops yielded 1.8 t/ha compared with dry sown crops which yielded 1.4 t/ha.
“The results from 2015 suggest that in a wet start to the season, on-row sowing is unlikely to provide any significant benefit compared with inter-row sowing.”
Dr Roper said earlier trials at Calingiri in 2012 and 2013 found that on-row seeding, compared with inter-row sowing, increased crop establishment in the drier season of 2012 but not in 2013.
“Furthermore, in both years, seasonal conditions during later crop growth and grain filling were sufficiently mild to ensure that crops sown on the old crop row did not show a yield advantage,” she said.
“However, improvements in establishment, combined with observations suggesting decreased severity of water repellence in crop rows sown on the old crop row, suggest that on-row seeding may be a useful and low-cost option for management of water repellent soils for crop production.
“The implications of long-term use of on-row sowing on soil nutrition, organic matter, soil structure and soil-borne diseases on water repellent soils needs further research.”
GRDC Western Regional Panel chairman Peter Roberts said water repellent (non-wetting) soils were prevalent in many crop-producing regions of WA, and posed challenges for crop production in terms of crop establishment, nutrition, and weed control.
“Research by Dr Roper has shown how some farmers on the south coast of WA manage water repellent soils by maintaining full residue retention combined with minimal soil disturbance,” he said.
“In this system, the severity of water repellency is actually increased but higher soil water content, and better crop yields, are observed than when these systems are disturbed by residue removal or soil tillage.
“Researchers including Dr Roper have attributed this higher soil water content to the maintenance of preferred pathways of water entry into the soil, often along the old intact crop root systems.
“This suggests that crops sown immediately alongside the old crop rows may have better access to soil water, and may perform better than crops sown in between the old crop rows.
“Farmer observations have supported this hypothesis.
“Subsequently, the research by CSIRO and DAFWA, conducted with funding support from the GRDC, was initiated to investigate crop emergence, yield and soil water repellency for crops grown on the old crop row, compared with crops sown in the inter-row space.”
Mr Roberts said the on-row trials were part of the collaborative research effort Soil Constraints – West initiative, supported by the GRDC.
Species
