Monday 20 April 2015

Variable Rate Irrigation and the Big Picture

Variable rate irrigation (VRI) has been mentioned in several posts to date, however we have not yet formally introduced the technology or the key to its potential benefits in farming. So we will start by looking at the big picture to hopefully provide you with some context to place this innovative irrigation technology. 

Irrigation demands about 80% of allocated freshwaters in New Zealand, which is similar to the global average; and the area of irrigated land in New Zealand has roughly doubled every decade since the 1960s. As the demand on freshwater increases so are the restrictions and charges placed on it. Farmers are realising the value of increasing their irrigation efficiency to ensure the long term sustainability of their freshwater, improve their nutrient management and decrease their water costs.

Efficient water management plays an important role in irrigated agricultural systems. Under conventional blanket irrigation (uniform rate irrigation or URI) many parts of irrigated fields are effectively over or under-irrigated due to spatial variability in soil available water-holding capacity, water infiltration rates and topography. Under-irrigated areas are subject to water stress, resulting in production loss, while over-irrigated areas suffer from poor plant health and nutrient leaching. 

Variable rate irrigation (VRI) addresses the need to achieve irrigation efficiency, aiming for best conversion of each millimetre of irrigation water to pasture growth. Irrigation efficiency is commonly referred to as application efficiency and depends on three main factors:
·         Applying the correct depth of water
·         Uniformity of application
·         The rate at which water is applied to the soil

Furthermore application efficiency is known as the percentage of applied water that is retained in the root zone or in the target area, after an irrigation event. Variable rate irrigation allows for irrigation efficiency of centre-pivot or linear-move irrigators to be optimised. This can be achieved through using a VRI system alongside soil mapping technology and site specific moisture monitoring. 

The Growsmart Precision VRI system was developed in Manawatu (New Zealand) by a team of talented engineers from farming backgrounds. The technology they developed is world-leading and the first system of its kind offering individual sprinkler control of the entire irrigator. This  allows farmers to apply exactly the right amount of water to specific management zones, giving full control to maximise yields and profitability.

Brian Bosch installed the first Growsmart Precision VRI system on his dairy farm in Wairarapa (NZ)
While there are many advantages of the Growsmart Precision VRI system that will be explored in greater detail in later blog posts one significant advantage is the understanding and support of the team that develop and manufacture the technology and the Zimmatic dealerships that sell and support he product. The team are passionate about precision agriculture and how it can be used to aid in the sustainable use of resources. And I will share with you some insider knowledge – a major focus of the current product development is based around this very premise.

In upcoming posts you will be introduced to some of the early adopters of the Growsmart Precision VRI technology to hear their story of how they have used the system to their advantage. To make sure you are notified when these stories come out subscribe to this blog by entering your email address in the box at the top right or "Like" the Growsmart Precision VRI Facebook Page. If you are wanting more information about the technology beforehand then visit

This post was written by Nicole Mesman and Sarah Elliot from Lindsay NZ :)