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Cost benefits of tackling water efficiency

9 October 2013

There is much that can be done to target your water resource where and when it’s needed, ultimately saving you money and helping produce ‘more crop per drop’. Despite GB usually getting its fair share of rain, it’s clear that seasonal rainfall levels are becoming increasingly erratic. So whether growers get too much or too little rainfall, the need for water management planning intensifies each year.

 
The demand for water is expected to double in the coming decadesi with global water resources subject to extreme pressure, and urban centres competing with growers for the increasingly scarce water supply, as river basins and aquifers dry up and the climate becomes more extreme. As demand increases, growers need to plan for and manage their access to water supplies and consider how their irrigation system best fits their crops, soil and location.
 
Chris Steele, AHDB Potatoes’s water and soils specialist, advises growers to focus on how to save water and use it efficiently, saying “The Water Framework Directive (WFD) demands efficient water management and compliance by 2015ii but irrigation scheduling is still not being used nearly enough by growers.  Just irrigating when your neighbour is irrigating is a false economy, not an efficient use of water and not necessarily right for your own crop and field. Precision technology for irrigation is becoming more available and growers can utilise this technology to test moisture levels in plants and soils and only irrigate when and where it’s needed.” 
 
Irrigation has been discussed in depth at several AHDB Potatoes events this season, with several systems being scrutinised to illustrate the most cost-effective methods available. At AHDB Potatoes’s Irrigation Workshop in June, a disposable drip system was shown to perform strongly on cost vs. benefit, with the total energy used to irrigate 20Ha for 45 hours at 49kWh, compared to the hose reel/rain gun with a total energy used to irrigate 20Ha for 80 hours at 1090 kWhiii.
 
Chris emphasises that “Water use and soil are inextricably linked so growers need to examine their soil structure. Soil compaction causes problems for water reaching the crop roots, where it’s needed. So when you first irrigate, check your soil again. Has the water gone down through the soil profile? If it’s stopping within the top inch it will just evaporate and be wasted. Conversely, if you over-irrigate, you will wash away nutrients and trace elements vital for crop development, so it’s vital to establish an irrigation system that works for your fields.” 
 
Having the proper irrigation equipment is a wise investment but training yourself or your staff to use it properly is equally important. Operators need to know how to set the system up correctly, adjust pressure, check flow rates, maintain equipment and possibly even fix any problems. Otherwise any new system may under-perform, leading to unsatisfactory results and poor return on investment.
 
Leading growers for PepsiCo know that achieving precise water use and irrigation for crops is vital. Adam Griffiths, Director of Agriculture Procurement, PepsiCo UK told us “We ran specific in-field trials in order to optimise our irrigation and we were pleased to observe a simultaneous improvement in yields. We actually surpassed our target of a one-third reduction in water use using drip irrigation, at the same time as growing 'more crop per drop’.” PepsiCo started the trials in 2011 on 100Ha of crops used to produce potatoes for Walkers crisps, and continued throughout 2012. The results are impressive and they saw a 7% increase in crop yield with 36% less irrigation water per tonne (2011) and a 5% increase in crop yield for 49% less irrigation water per tonne (2012)iv.
 
Adam continues “These results are helping us deliver on our commitments to sustainable farming and to being a sustainable business. We recognise the important role we can play in helping farmers become more sustainable and are delighted that the farmers trialling drip irrigation are now investing in these systems themselves.” 
 
As well as optimising their irrigation systems, some of the bigger organisations are going a step further by recycling water at their facilities. Water resources can be saved by a range of activities such as recycling irrigation water, re-using water from tuber washing and harvesting rain water running off stores – perhaps with the recycled water being stored in a purpose-built reservoir on-farm, giving growers access to ‘free’ water. 
 
The general adoption of irrigation water recycling has been slow in the UK, lagging well behind other leading potato producing countries such as Australia and New Zealand, and our industry could do much more to maximise water use. Initial costs to set these initiatives up can sometimes be considerable but once in place, the longer term benefits kick in.
 
It’s clear that planning and setting up the correct irrigation system for your crops could be one of the more significant business decisions you’ll need to make, but leading growers and industry experts can demonstrate that getting it right will make a sizeable difference to your marketable yields.
 
Potato growers can get more information on this and many other topics by visiting the leading potato industry event, BP 2013. Chris Steele will be on the AHDB Potatoes stand at the Yorkshire Event Centre, Harrogate, 27 and 28 November, to discuss water and soil management with levy-payers. For more details about BP2013 go to www.potato.org.uk/bp2013
 
Further helpful resources on irrigation and water use
 
AHDB Potatoes’s new guide ‘Irrigation and Water Use’; addresses key water management issues and examines how growers can plan ahead, manage irrigation, keep abreast of new legislation and smooth the peaks and troughs that cause crops to under-perform or even fail. See AHDB Potatoes’s Water webpage for information on the Water Framework Directive, general water advice, on-going levy-funded research, links and latest news; details here: www.potato.org.uk/water
 
AHDB Potatoes-funded R&D project: Water Use Efficiency Through Soil and Plant Water Balance. Details here. www.potato.org.uk/publications/r406-water-use-efficiency-through-soil-and-plant-water-balance
 
Links to the Environment Agency’s Water section: http://www.environment-agency.gov.uk/research/library/position/34159.aspx
 
 
 
 
iiWater Framework Directive (WFD): compliance implementation
Year WFD implementation Action by growers
2013-2014
Review progress of the first River Basin Management Plan (RBMP) cycle.
 
The River Basin Management Plan is a plan for protecting and improving the water environment and has been developed in consultation with organisations and individuals. It contains the main issues for the water environment and the actions needed to maintain and improve the water body status.
Review the key principles of water use to become efficient irrigators, paying particular attention to these areas:
  • Schedule your irrigation (including monitoring and auditing)
  • Improve efficiency of irrigation application equipment (energy, labour and water), fitting the right equipment to the right situation
  • Understand the links between the differences in soil texture and structure, soil water availability and crop production
  • The impacts of irrigation on diffuse pollution including nitrate leaching, phosphate and pesticide losses 
  • Store water in reservoirs if possible
2015 Review and update first RBMP’s. The default objective for all waters should be Good Status by 2015. To be reviewed
 
iiiSource: Wroot Water Systems 2013
 
ivBenched against traditional methods of irrigating potatoes with rain-guns or booms. Trials, run with Cambridge University, took place simultaneously in 4 different areas of the country with 3 different grower groups, on 3 different potato varieties across two crop years.
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