26 September, 2017
In this two-part series, CSD’s Extension & Development Agronomist for Central NSW, Bob Ford investigates field conditions and other factors that may impact establishment.
A well-established crop sets the standard for the entire season
High cotton yields are never guaranteed. However, if the crop has a strong start, obtaining yield potential is much easier. The aim for every cotton grower should be to plant the crop once, achieve the desired plant stand and evenness and get the crop off to a great start.
To achieve this, it’s critical that the seedbed is in the best possible condition, achieved through timely soil preparation and well maintained planting equipment, which enables growers to get started when planting conditions are right.
However, ground preparation isn’t always easy.The above average winter rainfall we experienced last season made it difficult for many growers to get onto their paddocks and pull up rows. This season has seen the opposite, with dry winter conditions providing ample opportunity for growers to renovate their soils in preparation for planting. Both of these scenarios present unique challenges.
Field conditions impact planting efficacy
Dry soils, although easier to access with machinery, tend to pull up large clods that make it difficult to plant seed into, potentially resulting in poor soil/seed contact. Another issue with dry soil is the breakdown of residual stubble from the previous crop. Although stubble has benefits in protecting small seedlings as they establish, a heavy stubble load can cause major issues at planting with ‘hair-pinning’ (where the stubble from last year’s crop bends as the planter passes over the soil, and is shoved into the ground, resulting in seeds planted at different depths). Trashwhippers are an effective tool, commonly used to remove stubble from the tops of beds, allowing discs to plant into friable soil. Under heavy stubble loads the use of a strip tiller could be more useful in providing a clean row for planting.
Stubble can also cause issues with irrigation; and in back-to-back country, poses a high risk of cotton volunteers germinating when watering up. In this scenario, pre-irrigation is preferred, followed by a knockdown herbicide application to control volunteers prior to planting.
The wet soils caused by excessive rain fall after picking can make it difficult to pupae bust, apply fertiliser and renovate soils for planting. Subsequently, irrigation furrows may be shallow, causing issues with watering up and first irrigation. Adequate rainfall helps to break down stubble, but incorporation is most effective with heavy stubble loads, in order to prevent disease build up.
Manage your soil prior to planting
If you’ve had a not-so-great start, there are a number of options to manage your soil prior to planting. The key is to understand what your situation is, and to adopt the most appropriate management techniques.
For example, after a dry winter or when soil renovation has not been ideal, using a heavy roller prior to planting can help to bust up clods and create a flat top hill for a better planter ride. Increasing planting rates by 1-3 kg/ha will also help to negate the issues associated with bed slump, poor seed/soil contact and non-uniform planting depths, once watered up.
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