Tom deCamp

Top Potato and Veg with Tom Decamp

Keep up to date with the latest potato and field vegetable information with this advice from Yara's field crop specialist Tom Decamp

Why a healthy canopy is essential for quality potatoes

18 June 2020

A healthy potato canopy is important in ensuring we maximise the plant’s ability to fill the ‘tuber sink’ thus producing as many marketable potatoes as possible, and improving profitability. Removing both biotic and abiotic stress will help to ensure a healthy, well-functioning potato canopy.

The ideal potato crop uses very limited amounts of the sugars to maintain its canopy, thus partitioning the majority into the tubers. When considering how to minimise the energy that is required to maintain a canopy, we need to focus on how we reduce the plant’s respiration to a minimum. A plant’s respiration rate will increase when it comes under stress,which reduces the amount of sugar produced during photosynthesis that is available for tuber bulking. It is essential to manage these stresses out of the production system and for abiotic stress such as temperature or drought relief can be aided by the use of biostimulants.

Nutrient deficiencies can be monitored through plant leaf analysis. Data from Yara Analytical laboratories reveals some of the key nutrient deficiencies found in potatoes to be phosphate, potassium and magnesium. Phosphate is of particular importance due to its role in the transport of the sugars from the leaf down to the ‘bulking’ tubers. The transport mechanism is an energy demanding process and the chemical energy is stored by the plant in the phosphate based molecule ‘ATP’. Magnesium, the central component of chlorophyll (leaf greenness), clearly has an important role in keeping the leaf canopy greener for longer. Potassium helps the plant regulate water and nutrient movement from roots, through the plant, to the leaves. Water movement itself is also a necessity in the transport of sucrose down to the ‘bulking’ tubers.

By removing both biotic and abiotic stress you will ensure a healthy, well-functioning potato canopy. This will give the best chance of maximising the important ‘tuber bulking’ period, and result in high, marketable potato yields.

Recommended action: During full canopy cover, two applications of YaraVita Magphos K @ 5 l/ha + YaraVita Biotrac @ 3 l/ha, with 14 days between applications.

Read more about increasing tuber bulking

 

Are your potatoes getting enough calcium?

15 May 2020

Calcium is a vital nutrient for potatoes and most aspects of tuber quality can be improved by having a sufficient supply of calcium during growth. It is required in the crop for the maintenance of cell walls, healthy leaf and tuber development.

Calcium deficiency is widely known as internal rust spot - a physiological internal defect in which small brown spots, due to cell death, appear in the tuber. This is directly related to a lack of calcium within the cell walls, meaning that they aren’t strong enough and when cell expansion takes place they collapse and necrosis occurs. 

Once calcium is incorporated into cell walls it can’t be redistributed therefore it is important to have a sufficient supply as new cells develop. As mentioned already, calcium is integral to cell walls and give the cells, particularly the skin, strength. Therefore a sufficient supply will help ensure the skin has a good finish as well as helping against physical damage which can occur during harvesting and handling. 

However it’s not only the timing of calcium that needs to be right but also the source of calcium that is being applied.There is a misconception sometimes that liming materials will contain and provide enough calcium for the crop but many liming materials are calcium carbonate based. This means that they aren’t very water soluble and consequently not freely available to the potato crop through the growing season.

As previously mentioned the timing of application to the potato crop is essential to flush the developing tuber with soluble calcium therefore the optimum application period is at tuber initiation. The ideal source of fully soulble calcium is YaraLiva Tropicote which should be applied at tuber innitiation.

Read more about calcium requirements of potatoes

 

Why is potato quality so important?

Listen to potato grower Jimmy Dagg from Crailing Tofts Potatoes near Kelso in the Scottish Borders tell us why potato quality is so important and why YaraLiva Tropicote Calcium Nitrate fertiliser is his first choice when it comes to spreadability, tracability and reliability.

Is there a better way of applying phosphate to potatoes?

12 March 2020

Following tradition many potato growers continue to apply phosphate using straights such as DAP or MAP but this might not be the best practice.

Phosphate is particularly important for potato establishment and has an important role in the development of shoots and in particular roots and this is why a sufficient supply is key in the early stages of potato crop.   The problem here is that phosphate is relatively immobile in the soil and relies on the roots being able to grow towards it rather than the phosphate moving through the soil towards the roots.  Couple this with the fact that potatoes are a particularly poor rooted crop and in the early stages often struggle to establish an effective root network capable of accessing water and other nutrients and you can see why this is an issue.

There are several ways to improve management of phosphate in potatoes by using YaraMila compound fertilisers rather than more traditional 'straight fertilisers'.

Better timing of P and K applications ensures that the phosphate is applied close to when the plant requires, so limiting the amount that becomes locked up by the soil.  This is favoured by applying P and K as compound fertiliser at or just after planting rather than as separate 'straight' applications prior to planting.

Better distribution of phosphate through the soil profile also helps plant uptake.  The best way to achieve this is to increase the number of fertiliser particles. Traditionally phosphate has been applied as relatively concentrated DAP di-ammonium phosphate, containing 48% P2O5 so there are relatively few concentrated particles. Similarly if the phosphate is applied in a blended fertiliser using DAP or MAP there is still the same problem of the phosphate being contained in relatively few particles resulting in a an uneven distribution of nutrient through the soil. 

However, if phosphate is applied as a compound fertiliser such as YaraMila Actyva S instead then every single prill or granule contains all nutrients and at a concentration of 14%  P2O5  there will be approximately three times as many particles.  This leads to more even spreading and a more effective distribution of nutrients throughout the soil which inturn leads to more even crop growth and increased yield

Read more about potato nutrition

Benefits of potato fertiliser placement at planting

06 March 2020

With planting about to start in the next few weeks this is maybe a good time to reflect on the benefits of fertiliser placement.

There are yield benefits from placing fertiliser at planting rather than broadcasting and from using compounds rather than straights as well as from optimising calcium, phosphate and zinc nutrition; here are some of the highlights from recent trials

Consistent yield benefit from placement of fertiliser at planting

Over the years Yara has carried out a large number of trials on the application of fertilizer to the potato crop, focusing on placement at planting. This has consistently given yield benefits, averaging 10.8% over 18 years of work. With continued legislation driving more efficient use of fertilizers such practices will become even more important. Applying fertiliser to the planted areas and not broadcast all over must be more acceptable from an environmental risk point of view. 

Application accuracy is a key focus for Yara, particularly in the potato sector. YaraMila compound fertilisers such as YaraMila Actyva S can bring benefits over straights for the delivery of nutrients to the crop, with a 7.8% yield increase over straights in a long-term trial at Hanninghof Research Centre. 

Other trial work carried out by Yara includes the benefits of calcium for tuber quality, foliar phosphate applications to improve tuber numbers and tuber size and just recently, the impact of zinc, where in 2014 a 1l/ha application of YaraVita Zintrac 700 lead to a 5% yield increase.

Read more about potato nutrition

Potato nutrient requirements

12 February 2020

The potato crop requires potassium in large quantities, 50% more, in fact, than nitrogen. A 38.5t/ha crop can remove more than 120kg/ha of nitrogen whereas it can remove over 200kg/ha of potassium. Both of these macronutrients are important throughout vegetative growth, tuber formation and bulking.

Nitrogen is important for leaf and tuber growth and is recycled from lead to the tuber during bulking, the same can be said for potassium. When thinking of potassium then as you can see from the removal values that it is key for high yields and maintaining tuber integrity.

Phosphate is also required in relatively large quantities during early growth due to its importance in root and shoot development and tuber set but also later on in the season for bulking.

Calcium is a crucial nutrient  as it plays a role in important quality parameters. Potatoes need calcium to strengthen the skins of the tubers; providing better resistance to many diseases (black scurf, silver scurf and common and powdery scab) and also a better skin finish.   Calcium deficiency also causes internal rust spot so it’s essential to apply calcium at the right time but also ensure the correct source of calcium is used. For example, liming materials won’t supply plant-available calcium to the crop therefore it won’t supply sufficient supply to meet the demand.

Magnesium is important during tuber bulking where it plays a major role in maintaining tuber quality and is therefore a key nutrient.

Micronutrients are also important to ensure the crop has all it needs to produce a good, quality yield. Zinc and manganese are key to help the crop’s defence against powdery and common scab as well as maintaining skin finish.

Read more about potato nutrition >

Why is sulphur so important for potatoes ? Yield or common scab control

18 October 2019

It is well-known that sulphur deposition has decreased to almost nothing meaning no more sulphur is deposited on the land – sulphur applications are therefore a must.

When thinking about sulphur on potatoes there is, of course, the important relationship between sulphur and nitrogen. Nitrogen can’t be taken up by the plant or utilised as efficiently if there is a deficiency in sulphur. The N:S of uptake per tonne of yield in potatoes is 8.5 which is similar to cereal crops and trials have shown up to 15% yield increases from 16-30kg S sulphur applications to potatoes.

However, does sulphur have another important part to play in the potato crop?

Quality is very important when growing potatoes, especially their skin finish, therefore common scab can be a real issue. Common scab is more prevalent on high pH soils (alkaline) therefore the theory is that acidifying the area around the tuber will help control common scab. Sulphur helps to acidify the soil therefore applications of sulphur should help with control.

Sounds simple then – apply sulphur and you won’t get common scab…unfortunately it’s not as easy as that. Trials work Yara did showed that there was no consistent effect of applying sulphur for common scab control at the usual 16-30 kg S. Further work on higher rates, 60kg S +, showed more promise, but even at these very high rates there was only a marginal effect on the scab.

So, when thinking of sulphur on potatoes it should be to increase yields and nitrogen use efficiency and not common scab control. The most effective method of controlling common scab is therefore still irrigation, ensuring the moisture reaches the depth of the tubers.

Read more about potato nutrition

Fertiliser placement at planting

24 August 2019

With lifting about to start this is maybe a good time to reflect on potato yields and look ahead to next season before lessons are forgotten.

There are yield benefits from placing fertiliser at planting rather than broadcasting and from using compounds rather than straights as well as from optimising calcium, phosphate and zinc nutrition; here are some of the highlights from recent trials

Consistent yield benefit from placement of fertiliser at planting

Over the years Yara has carried out a large number of trials on the application of fertilizer to the potato crop, focusing on placement at planting. This has consistently given yield benefits, averaging 10.8% over 18 years of work. With continued legislation driving more efficient use of fertilizers such practices will become even more important. Applying fertilizer to the planted areas and not broadcast all over must be more acceptable from an environmental risk point of view. 

Application accuracy is a key focus for Yara, particularly in the potato sector. YaraMila compounds can bring benefits over straights for the delivery of nutrients to the crop, with a 7.8% yield increase over straights in a long-term trial at Hanninghof Research Centre. 

Other trial work carried out by Yara includes the benefits of calcium for tuber quality, foliar phosphate applications to improve tuber numbers and tuber size and just recently, the impact of zinc, where in 2014 a 1l/ha application of YaraVita ZINTRAC 700 lead to a 5% yield increase.

Read more about potato nutrition

 

Boron deficiency in brassicas

8 August 2019

All brassicas have a high requirement for boron and deficiency can cause poor crop establishment together with increased plant losses and ultimately reduced yield.

Boron has several key roles in plants which include cell wall biosynthesis, carbohydrate and protein metabolism, cell division/elongation and also root and shoot growing points. 

Root and shoot development are obviously key to establishing the plant early on to ensure that it gets off to the best start to help combat pests and diseases. Also during this period the plant is growing very rapidly and therefore having a sufficient amount of boron present is essential to keep the root and shoot development rate optimum. 

Boron is the only nutrient which, when in short supply, can accelerate physiological processes instead of reduce them and therefore abnormal growth can occur. Symptoms of boron deficiency often start on the younger leaves of the plant and they appear crinkled, deformed and brittle. Necrotic patches may appear at the leaf margins and the plants may appear stunted. Stems can also be affected with hollow lesions occurring and splitting of the stems. Some of these symptoms can be made worse by sandy, alkaline soils low in organic matter as well as high levels of calcium present. 

Vegetable Brassicas require boron in quite large amounts where it helps control nutritional disorders such as tip burn and hollow heart. Find further information on the symptoms and causes of Boron Deficiency in Vegetable Brassicas

Yara brassica trials have also highlighted the synergy between calcium and boron, improving the uptake of each nutrient and improving the control of associated disorders, not only in brassicas but also in other crops showing a response to calcium and boron such as potatoes. 

YaraLiva NITRABOR contains a balanced combination of soluble nitrate nitrogen, calcium and boron that can be safely applied to green crops right up to harvest without fear of scorch to enhance both the quality and marketable yield of vegetable brassicas. 

Read more about vegetable brassica nutrition

 

Key nutrients for healthy potato yields

8 March 2019

The potato crop requires potassium in large quantities, 50% more, in fact, than nitrogen. A 38.5t/ha crop can remove more than 120kg/ha of nitrogen whereas it can remove over 200kg/ha of potassium. Both of these macronutrients are important throughout vegetative growth, tuber formation and bulking.

Nitrogen is important for leaf and tuber growth and is recycled from lead to the tuber during bulking, the same can be said for potassium. When thinking of potassium then as you can see from the removal values that it is key for high yields and maintaining tuber integrity.

Phosphate is also required in relatively large quantities during early growth due to its importance in root and shoot development and tuber set but also later on in the season for bulking.

Calcium is a crucial nutrient  as it plays a role in important quality parameters. Potatoes need calcium to strengthen the skins of the tubers; providing better resistance to many diseases (black scurf, silver scurf and common and powdery scab) and also a better skin finish.   Calcium deficiency also causes internal rust spot so it’s essential to apply calcium at the right time but also ensure the correct source of calcium is used. For example, liming materials won’t supply plant-available calcium to the crop therefore it won’t supply sufficient supply to meet the demand.

Magnesium is important during tuber bulking where it plays a major role in maintaining tuber quality and is therefore a key nutrient.

Micronutrients are also important to ensure the crop has all it needs to produce a good, quality yield. Zinc and manganese are key to help the crop’s defence against powdery and common scab as well as maintaining skin finish.

Read more about potato nutrition >

Discover your limiting factors with soil analysis

10 February 2019

UK soils have changed a lot in the last few decades; whether it’s the 97% sulphur deficiency found in soils sampled or the low organic matters across arable land. Therefore everyone knows the importance of taking a soil sample; but should you be investing in more than just basic soil analysis?

The basic analysis will give you P, K, Mg and pH; which is a good start but what about Ca, S, Mn, Cu, B, Zn, Mo and Fe? All are important to plant nutrition and you may be unaware that your soils are low in one or more of these elements. Soil sampling is about finding the limiting factors on your farm and being able to make sure they aren’t impacting upon yield – think Liebig’s barrel!

Yara Analytical Services have processed over 20 million samples. This huge dataset has shown that after removing all the soils with limiting factors such as P < index 2, pH <6.5 and micronutrient deficiencies then less than 20% of UK arable soils growing wheat have sufficient levels. When you look at soils sent in for oilseed rape fields then even less are sufficient.

By taking a broad spectrum soil sample you’ll know about these issues before it’s too late – when symptoms appear and yield is already taking a hit. Liebig’s law of the minimum states “A deficiency of any single nutrient is enough to limit yield”. With yields being pushed further, whilst costs savings are sought (such as P and K holidays) you could be limiting the effectiveness of any increased nitrogen applications.

Read more about Yara soil analyses >

 

Potato agronomy and fertiliser advice
Potato agronomy and fertiliser advice

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