By Dr Michael Bange

Research agronomist and CSD’s Commercial Research Manager, Dr Michael Bange offers his perspective on using the FastStart program’s tools for crop establishment based on the knowledge he has gained through years of research and experience.

Introduction

Last season across the regions saw one of the coldest starts to a cotton season experienced by the industry and the impact of these cold temperatures certainly showed up in attempts to establish cotton successfully.  As part of the FastStart collaboration, CSD and Syngenta  assist growers and advisors with information and tools to help establish a crop successfully.  A number of sources of information and tools are provided as part of this collaboration to assist with determining when to plant the crop in order to achieve good establishment.  These include the FastStart soil temperature network and the traffic light system which provide soil temperatures and alerts for when conditions are not ideal to establish a crop. Certainly, last season we saw these tools used heavily due to the conditions, in fact in some regions the tools did not at any time give the “green light to go”, because the temperatures remained low throughout the traditional planting window.

Image 1 – Tools and calculators available through FastStart.

Have You got the Green Light for Planting?

Planting is one of the most important operations on the farm.  It sets the standard for the entire season and paves the way for achieving optimal crop growth and ultimately yield.

With the use of the FastStart soil temperature network a traffic light system has been developed to help gauge the current and near future conditions at planting.  Let’s start by what I consider the important elements of successfully establishing a crop and see how they relate to the traffic light system.  My perspective is that once a seed has access to adequate moisture and the right agronomy (eg. A good seed bed and the seed is planted correctly), it is then all about access to ‘energy’ in the form of heat.

Figure 1: The FastStart traffic light system is used to quickly gauge the conditions at planting.  If you cannot give a green tick to one element of the then consider stopping (a red light). One green tick, then be cautious, and all green ticks means that there is potentially enough energy or heat to allow establishment to occur.

My key considerations in relation to the traffic light system include:

1. Is there enough energy/heat in the soil? The soil is an important reservoir of stored heat (especially when the soil is moist) and only big shifts over a few days will move temperatures.  Obviously, the texture of the soil and the amount of moisture in the soil will change this.  Lighter textured soils are susceptible to big swings in temperature, beach sand is the extreme example.

This point pertains to the first element of the traffic light systems where temperatures at 10cm depth at 8.00am need to be 14°C or above.  The caution here is when using the FastStart soil temperature network, be aware of the differences between the weather station and the actual field you are comparing.  The FastStart soil sensor provides a guide and will not always represent your exact field conditions.  Therefore, there is no substitute for an actual measurement of soil temperature in your fields of interest.  Meeting this element of the traffic light system gets the first tick to help achieve a green light for planting.

2. Will the atmosphere provide enough energy in the near future for soil temperatures to rise? The first consideration relating to this point is that air temperatures will be high enough in the near future to raise soil temperatures; and secondly, the increase in temperatures over a week will remain on a rising plane or be sustained. It is possible that temperatures can be adequate at the start of a forecast but towards the end of the forecast they may force the situation back into unacceptable conditions.  Only a detailed analysis of the forecasted temperatures in terms of the overall amount of energy and the temperature pattern of the forecast will help with understanding this dynamic fully.

 

Meeting these points contributes to the green light for planting, as the second element of the traffic light system.  The amount of energy is represented by the forecasted day degrees (Figure 2) and the pattern is represented by the temperatures forecast over the upcoming week (the same used to generate day degrees).  The increase in day degrees (whether it be DD12 or 15/32) represents the potential for more energy that comes into the system.  Any increase in average air temperature over time will help but it needs to be enough to generate changes in soil temperature above 14°C at 8.00am. Average air temperatures (or soil temperatures below 16°C have been shown on many occasions to prevent vigorous establishment, if at all).  Note that an average daily temperature is not the same as a minimum temperature or a temperature measured at 8.00am.  Similar to point 1, it must also be considered that air temperatures forecasted for a nearby weather station are not always completely reflecting soil temperatures in neighbouring fields. in soil temperatures.

3. As a final point, the traffic light system importance (or the weight of the tick) can differ depending on various combinations of the factors described above. For example, a warm soil (that is a soil temperature above 14°C at 8.00am) is much more important than the forecast.  Energy is already present in the system, and large changes in the forecast are needed to shift it. One might still consider planting with these conditions. In contrast, if a soil temperature is cold, then forecasts and patterns of temperature play a much more important role in decision making.

Figure 2: A screen shot of the FastStart soil temperature network accessed via CSD tools.  Here we see the temperature at 8.00am measured at a FastStart weather station. The risk associated with accessing energy to help normal and low-density seed emerge, and the forecasted air temperatures that can help confirm the pattern of temperatures looking forward.  To get the green light for planting a number of these elements have to get the green tick!

Other factors that need consideration

CSD have developed a number of information sources and tools that account for factors that impact final plant population. These include:

• The Cotton Planting Rate Calculator – Combines many years of trial work that capture the effects of impacts on germination and emergence to help estimated the seeding rate needed.
• Field Ranking Score at planting – A visual guide to assist in assessing the risks associated with varied seedbed conditions.
• Impacts of Planter Setup – An assessment of different impacts on planter setup that lead to differences in seed rate and ultimately establishment.

Looking forward

CSD along with Syngenta through the FastStart collaboration continue to invest in initiatives to help cotton establishment.  Key initiatives are in place to extend the FastStart Soil Temperature Network as well as seeking better ways to predict the impact of temperature on cotton establishment. To get the most out of their cotton seed, CSD members have access to these tools and many more. We are continuously looking for ways to improve the tools available to growers, so if you have any suggestions or feedback, please let your local Extension and Development Agronomist know.