Diggin’ deep: Understanding your cotton crop’s soil condition
Soil is the root of all growth, providing essential nutrients, water and support for your crop’s development. To achieve uniform cotton crop establishment, strong seed emergence and optimise potential yield, the condition of your soil plays a vital role.
Before planting, it’s recommended you undertake an assessment of the field’s soil strength, moisture content and bed consolidation to address any issues with its condition. Consider –
- What is the soil type?
- Has moisture infiltrated to adequate depth within the seed zone?
- Is the rainfall uniform across the field?
- Will the seedbed maintain structure without becoming waterlogged and crusted?
In dryland or irrigated cotton, well-formed beds, sufficient seed-soil contact and uniform, moderate soil moisture levels help prevent seedling mortality, staggered germination or gappy stands. To aid your soil assessment, familarise yourself with the conditions below that can affect cotton establishment.
Surface crusting
Soil surface crust can impede the emergence of cotton seedlings, resulting in a patchy plant stand or occasionally, the need to replant. Simulated rainfall can also form a hard crust on the soil, producing strong mechanical impedance and preventing seedling emergence. The soil strength, rather than poor soil aeration, inhibits emergence.
Waterlogging and compaction
Soil sodality, machinery compaction or flat/depressed land can result in poor field drainage after irrigation or rainfall.
If beds are too wet at planting, a shiny, smeared planter slot can form making it difficult for young roots to penetrate. As a result, young seedlings often develop a J shaped root or die from moisture stress, even if there is plenty of moisture below the seed.
The effects of waterlogging and compaction may make plants more susceptible to seedling diseases and seed mortality.
Cloddy or hard soil structure
Hard, dense subsoil conditions from soil compaction, smearing by machinery, or sodicity can impede root development and water infiltration.
A poorly consolidated or cloddy hill can collapse and crack when water hits it, dropping seeds to greater depths and resulting in poor or variable establishment. In cloddy seedbeds, fine materials may be wet while larger clods remain dry, drawing moisture away and drying the seedbed.
Prevention grows a field of results
To reduce the risk of poor soil conditions, employing preventative strategies is recommended:
- Break down, incorporate or remove stubble from the planting line
- Direct drill into surface stubble mulch to maintain soil structure
- Ensure soil tilth is fine to enable good seed-to-soil contact
- Avoid sowing too deeply in crusting-prone soils
- Follow sowing with irrigation on some soil types to delay crusting and allow time for cotton seedlings to emerge
- Consult the Field Score to guide your seedbed preparation
- Understand your planting method and adjust as required
- Planting dry and watering up: Advantageous for hot climates as it cools the soil and enables rapid establishment. Ensure consistent seedbed consolidation to prevent collapse when irrigation is applied.
- Planting into moisture: Whether from pre-irrigation or rainfall, regularly check moisture levels in the seed zone. Planting depth may need adjustment throughout the operation due to movements in seed zone moisture.
For more information on soil condition assessment and practical tips, download the FastStart™ Cotton Establishment Guide – www.faststartcotton.com.au/downloads .