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Irrigation and effective early season water management

Publication Date: 
23 May 2017

Thankfully, we have seen signs of some much-needed rain recently, however the need for efficient water management is as important as ever for UK potato growers.

Dr Philip Burgess, Head of Knowledge Exchange for AHDB Potatoes, said: “Every season is different. Comparing one season to the last doesn’t often help.”

“What is important is that we understand the principles of efficient water management and apply them to the current agronomic situation.”

With a few exceptions, irrigation should be targeted to begin when the first plants tuberise (around two to three weeks after emergence), to ensure that the ridge or bed is close to field capacity by the time tuber initiation occurs in the majority of plants.

But as well as using modern technology to assess the need for water. Phil is keen for growers and agronomists to find out for themselves.  Phil said: “Get out there with a spade and look at what’s happening. Dig some of the most advanced plants and look for the first signs of tuber initiation.”

“It’s also essential to know your soil type and understand its water requirements. Go back into the field after its been irrigated and check e moisture has spread through the profile.”

But getting started at the correct time is critical to success in controlling common scab.

Mark Stalham has worked extensively in this area and he recommends…

The main driver for early season irrigation in the UK is tuber quality and as tolerance levels only seem to tighten then control of this continues to be in the spotlight.

When properly applied, the use of irrigation has long provided an effective control measure following tuber initiation. But can less water be used in some instances? This might save the resource itself or perhaps more importantly allow it to be used in areas it has highest return.

Setting these priorities requires detailed knowledge of crops, soils and their associated quality requirements. For example it’s not always necessary to control common scab completely in processing crops. The most critical time is these crops occurs 2 to 3 weeks after tuber initiation.

With varying soil types across the farm it might be possible to reduce the number of applications and achieve the same level of control in different fields.

Once the regime has started the next question is when can you move on from the common scab control programme and start to irrigate for maximum yield?

Mark Stalham has some pointers here for you…

How long do you need to continue the scab control regime?

For Maris Piper, with a typical commercial emergence period irrigate for 31 days after start of TI at the appropriate SMDs from Table.

Maintain moderate soil moisture deficits [19mm (sand) to 31mm (silt loam)] for 3-4 weeks after TI in scab-resistant main crop varieties.

Potato varieties for the salad market are at risk from common scab infection for much longer than main crops owing to the small size of tubers. Six weeks’ scab control is sufficient, even in varieties such as Maris Peer or Charlotte and, as short as four to five weeks in more resistant varieties.

Avoid over-watering soils during the scab control period, particularly in the first week after TI. Excessive irrigation, or soils kept above field capacity for substantial periods during the control phase, can aggravate other disease problems and impede root growth, leaving the crop more susceptible to drought later in the season.

Uneven or protracted emergence lengthens the control period required. This increases costs, water use and risks higher levels of scab. Seed management, soil cultivation, planting and agronomy can all increase crop uniformity and improve scab control.

As always in life, moderation is key and you need to be aware of the issues associated with over watering as well.

Irrigation Management – Top tips

  •  Make sure that meters are in good working order and properly fitted;
  •  Check irrigation systems and replace worn or broken items before the start of the season;
  •  Make sure that irrigation systems are properly set up and operated in accordance with an accurate and reliable irrigation scheduling system;
  •  Ensure you are prepared to change your irrigation plans if necessary;
  •  Prioritise crops and fields in terms of water need;
  •  Choose irrigation times carefully, e.g. avoid the heat of the day; irrigate at night, if possible;
  •  Undertake a water audit. Know the cost of your water, calculate crop per drop.

 

 

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