Friday 29 May 2015

Evaluating Potential VRI Returns with an EM Survey

In the previous blog about the EM surveying service provided by Agri Optics I touched on an aspect of our software platform which helps you evaluate the variability in monetary terms. In this post I will go into it in more detail and explain how it can help you evaluate the likely financial benefits from the installation of VRI. This is another service that is unique to Agri Optics in New Zealand.

The VRI Design Evaluator allows you to enter the cost of your VRI system, (for example a  standard budgetary figure of $100/metre of pivot) then put your expected yield and value of crop – for example  wheat yielding 12 t/h at $400/t or grass at 25c per kgDM and 12,500kgDM/ha per year.
The software works on the theory that by not over watering the high EM areas or under watering the lighter low EM areas you are not inhibiting yield from water stress and therefore getting a yield penalty.  These areas will then yield more like the average EM area i.e. 12t/ha. By altering the water application to match the soil’s requirements you are reducing the effect of soil variability therefore gaining a greater yield, as there are no water based yield penalties.

This is a very useful tool for showing the amount of yield benefit that can be made by applying VRI to your lateral or pivot. However it doesn’t take into account the added benefits of savings in water, power, a quicker return time and in a dairy scenario reduced track maintenance, reduced lameness and the milk penalties tied to that. Nor does it take into account environmental benefits from reduced nutrient leaching or soil erosion.

In the screenshot above, using a yield of 12t/ha for wheat at a value of $400/t, a cost of VRI at $100/m (figures underlined in green) on a 476m pivot at a total cost of $47,696 (underlined in blue) there is an annual benefit in the region of $43,302 (underlined in red), so in this scenario the VRI system would pay for itself by the second year.

This can be very useful information for anyone who is trying to decide if VRI would work for them and is one of the options we can provide when conducting an EM survey.

Chris Smith - Agri Optics NZ Ltd.