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Creating a good seedbed: the basics

We asked Edward Gilbert, sales and marketing director at Standen Engineering Ltd, to run through the principles of potato cultivation techniques and offer advice for new operators on how to get the best out of their machinery.

The choice of implements used to prepare land for potato planting will depend on soil type and, in particular, the amount of stone or clod which needs to be removed to create the perfect ridge. The first step in the process requires little in the way of explanation. Bed formers or ridgers from Standen and other manufacturers are essentially similar in design, with a choice between either shearbolt or auto-reset construction and optional subsoiler and bed loosening tines. Where competing machines tend to differ is in the shape of the plough or ridging bodies.

‘Some potato growers like a square bed while others want a wide trough in which to bury the stone,’ Edward Gilbert observed. ‘People are often very particular about bed shape and we offer different ridging bodies to suit different soil types, as do most other manufacturers.

‘A bed tiller is then traditionally used to break down the clod size to produce a nice seedbed for your crop and to speed up the destoning or declodding process, while making sure that you are utilising all of the soil. If the land is very cloddy and you just go through with a soil separator a lot of that material is going to disappear into the trench.

‘There are soils that will never see a bed tiller,’ Mr Gilbert conceded, ‘though some people are now using them to put on Vydate or Nemathorin ahead of planting; they are going through with a rotary tiller to incorporate the granules where they have a problem with PCN, though generally the process is used for heavier land where growers are trying to maximise the amount of soil retained in the bed.

Turning to soil separation equipment Edward Gilbert summarised the choices available to growers.
‘If you just have stone and no clod you’d go for a web machine but webs aren’t very good at breaking up soil,’ he commented. ‘Where the land is very cloddy but there is no stone you need a machine fitted with stars. If you have a mixture of soil types, some land with stone and some that’s cloddy, then you want a machine that will do both so you’d choose one with a star/web combination such as our UniPlus separator or Grimme’s Combistar.

‘The Grimme machine uses stars followed by a web but the UniPlus is unique in that the web runs underneath the last five rows of stars. Any stone that falls through the stars drops onto the web which means there is still a chance of catching it and putting it into the trench rather than into the bed. In effect, the machine has a double sieving action, and it also uses a much larger diameter star so it’s more aggressive and very hard wearing.

‘The thing to be wary of is that you can have different spacings between the stars. You can alter the gap but you’d normally do that from new rather than adjusting it later because it is quite time consuming. For very light land with a lot of small stone, for example, you’d close up the gap and fit just one or two spacers. On land where you are just declodding then you would probably go to a three spacer setting which allows a little more of the soil to drop through.’

Read the full article in our March/April edition.

Take your time and minimise drift

Sprayer operators will play a hugely important role in achieving effective weed control in potato crops this season. Timing and fine-tuning of spray treatments can contribute as much as the efficacy of the products used, according to Syngenta’s application specialist.
For optimum results from pre-emergence and early post-emergence herbicide treatments, James Thomas advocates the mantra: Go Low, Go Slow and Get Covered. He points out that spray drift can be a major factor in situations where results are disappointing, in terms of both product wasted and poor overall coverage of the soil surface. Furthermore, there is an increased risk of environmental losses and damage to neighbouring crops, as well as problems of perception when the public encounter bad practice.

‘A bare soil surface is one of the most challenging targets for spraying, since there is no crop to intercept and hold spray droplets,’ he says. ‘Small droplets can remain suspended in the air, and are extremely susceptible to loss from wind movement or thermal up-drafts.’

Syngenta research has demonstrated the efficacy of new 90% drift reduction nozzles for pre-emergence herbicides (see Potato Review, January 2018). The design of nozzles such as the Teejet TTL 110-05 creates larger droplets with sufficient momentum to reach the soil surface and achieve better coverage than conventional flat fan nozzles. They are also significantly less susceptible to drift. Trials have shown a significant improvement in weed control with Defy-based grass weed programmes.

Mr Thomas believes that such drift reduction capabilities could enable spray operations in a wider range of conditions, which would in turn facilitate more timely pre- or early post-emergence applications; operators have reported that the nozzles typically provides five extra spray days over the course of the season. He emphasises, however, that as with all nozzles options, it is essential to maintain best practice for sprayer set up and operation in the field.

Modern sprayers are very capable of operating at faster speeds but that can result in greater turbulence and increased risk of drift, he observes. Trials have shown that doubling forward speed to 16 km/hr could result in 150% more drift, along with a 40% reduction in weed control from a pre-emergence application.

‘Slowing down will give a step change improvement in drift reduction but has to be balanced with the practicality of getting the acreage covered at the required timing,’ he explains. ‘Practical measures, such as improving filling routine to speed-up turnaround, ensuring adequate water supply around the farm and using bowsers, can all increase sprayer output to compensate for a slower operating speed.’

Slowing down will also greatly improve boom stability, which is another contributing factor for spray drift, he adds. A boom operating at a height of one metre would result in 10 times greater drift than one operating at the correct height of 50 cm.

Read the full article in our March/April edition.

Embrace new chemistry for successful weed control

Growing quality potatoes has always been a challenge but following product losses and restrictions to a number of key herbicides in recent years growers must look at new actives and prepare for life after diquat, says one well-known Norfolk agronomist.

Andy Alexander, who advises on over 1200 ha of potatoes each year has worked as a consultant, a grower and a buyer of stored potatoes for over 40 years, experience which he regards as a major advantage when talking to his customers.

‘It is critical to understand the whole farm business when you offer advice. Knowledge of the growers end market (whether they are a crisper, a chipper or growing for the salad shelves) is very important in understanding the subtle differences in the type of agronomic advice you might offer,’ he explains.

Mr Alexander used Gozai (pyraflufen-ethyl) in 2017 and confirms that he was satisfied with its performance as a contact herbicide. ‘When trying any product for the first time you must assess it under different growing conditions. I trialled Gozai using three different varieties on three different soil types with varying chemical partners in order to gain as much knowledge as I could,’ he confirms.

The first of the trials was conducted on a sandy clay loam soil with the variety Innovator. ‘I used Gozai at the correct rate of 0.4 litre/ha 4 to 5 days before the crop began to emerge. It was applied alongside prosulfocarb at 3.5 litres/ha and Praxim (metobromuron) at 2.5 litres/ha. The land was well irrigated so soil moisture levels were good and overall weather conditions at application were favourable.

‘On the second site (a sandy loam soil with stones) I partnered Gozai with Sencorex (metribuzin) at 0.5 kg/ha and prosulfocarb, again at 3.5 litres/ha. Once again, my field notes recorded that the Gozai had done its job. On the third site (a grade one silt) where the grower had planted the variety Russet Burbank I again applied Gozai at between 4 and 5 days prior to crop emergence alongside Praxim at 2.5 litres/ha and prosulfocarb (3.5 litres/ha). On this site I did see some late emerging fat hen and annual meadow grass but I put this down to poor initial canopy growth that failed to smother the later emerging weeds.

‘Gozai is a more than viable alternative to either diquat or carfentrazone,’ he suggests. ‘It is ideal for early season use and it offers control across a broad weed spectrum. It mixes well, but do not cut corners – you must use 200 litres of water to achieve the right level of coverage.’

Read the full article in our March/April edition.

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