08 August, 2017
With dry conditions continuing and little rain forecast in the spring, conditions for planting dryland cotton could be very challenging this season. Where surface moisture is not available, growers may consider deeper planting and moisture seeking techniques to get the crop established.
The cotton seedling is not renowned for having ability to handle deeper planting. Depending on the soil temperature, the ideal depth for planting cotton is 2 to 4cm. Planting deeper than 5cm will certainly “test the friendship” and establishment percentages will fall dramatically beyond this depth.
The options for deeper planting and moisture seeking should be weighed up against waiting for rainfall. In central and western regions, the planting window for Bollgard 3 makes the latter option more appealing. In fact, later planting often improves the yield and quality of dryland cotton. In eastern and southern growing regions waiting for planting rain may not be an option as the planting window is shorter.
When considering moisture seeking cotton, you need to be sure your planting equipment and soil type are suitable. Some growers have used trash whippers set aggressively to move dry soil to the side and allow twin disc machines to plant the seed into deeper moisture. The limitation of this is that the trash whippers can lift the planting units and planting depth into the furrow is compromised. Modified planters with air bags or other systems to ensure the planting discs are fully engaged will help but often the planter itself may not be heavy enough to move sufficient surface soil and hold the planting discs at depth.
Other growers have used tyne planters to aggressively chase moisture. Depending on the soil type, this has worked well or been a complete failure. The condition of the soil is particularly important. Soft self-mulching soils are the most forgiving to moisture seek.
Self-mulching concrete soils – with hard layers that “break out” into a cloddy surface are not suitable and should be avoided. Furrow planting may require additional work to close the furrow and press the seed. Heavy chains dragged in the plant line can be useful.
Planting rates will need to be increased to allow for higher establishment losses. Planting into a furrow can be an advantage or disadvantage. Any showers after planting are concentrated in the plant line and assist establishment and early growth. Heavy rain after planting will severely waterlog, bury and kill germinating seedlings – but at least you will have moisture to replant!
By Rob Eveleigh, Extension & Development Agronomist – Namoi Valley
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