Sulphate of Potash and Tropical Fruit

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Most tropical species are characterised by fast growth, involving short periods of high nutritional requirement. In addition, tropical fruit is frequently grown in poor soil conditions. Fertilization programmes should, therefore, take into account these two constraints.

Fertilization prior to planting should ensure good rooting and rapid plant development, whereas annual programmes should aim at a balanced nutrition to optimise fruit yield and quality. Choices will be largely guided by soil analysis, subsequently complemented by foliar diagnosis.

Dragon fruit, durian, guava, jackfruit, longan, mangostan, passion fruit, papaya, rambutan, sapodilla and star fruit are the most important tropical fruit species after bananas, mango and pineapple.

Although the crops can be very different, their common characteristic is a high requirement for potash in order to produce marketable fruit. The potassium/nitrogen ratio is generally greater than one, as shown in the table below.

Sulphate of potash (SOP) is ideal for tropical fruit, which are sensitive to chloride or excess salinity. Its effect on fruit yield compared to muriate of potash (MOP) is now well documented as shown in the two illustrations below.

N P2O5 K2O g per tree per yearDragon fruit 540 420 500

Durian 800 400 600

Guava 60 60 85

Longan 400 180 400

Mangostan 1200 600 1200

Papaya 45 45 60

Passion fruit 135 30 150

Rambutan 420 420 600

Sapodilla 420 420 600

Star fruit 600 600 850

Mineral requirements

LonganDragon fruit

The search for rapidly available nutrients

What form of potassium?

Effect of the form of potash on production of dragon fruit

Kg/t

ree

Source: Vietnam (2003)

Effect of the form of potash on production of longan

Kg/t

ree

Source: Vietnam (2003)

SOPControl MOP

SOPControl MOP

New research into potash fertilization shows the key role potassium sulphate plays in producing sweet, tasty fruit with good keeping quality. This is due to its beneficial action in the formation of sugars and organoleptic components.

As a result of its action on the transport of sugars from the leaves to the storage organs, sulphate of potash also has a direct influence on the calibre of the fruit.

Tropical cropping conditions mean low organic matter and the risk of leaching. These two factors often lead to sulphur deficiency. Among the other benefits provided by sulphate of potash is the supply of sulphur in a form that is readily taken up by the plant.

SoluPotasse®, Tessenderlo Group’s highly soluble SOP, is widely used in modern papaya production and a standard fertigation programme is presented below.

The example also shows that SoluPotasse® allows potassium to be applied alone, when nitrogen is not suitable for high quality production.

There is great potential for the growth of tropical fruit on the world market. Using sulphate of potash for tropical fruit production guarantees a greater volume of fruit with a quality that is better adapted to the export market.

K2O K Yield Fruit/flesh Taste(g/tree/year) fertilizer (kg/tree) ratio

200 KCl 237.23 19.05 +

750 K2SO4 288.24 19.79 ++

1050 K2SO4 343.16 22.50 +++

1350 K2SO4 308.19 22.72 ++++

1050 KCl 283.37 21.97 +

Effect of the type of potash on durian production and quality

Duriantree

Papaya

Urea MAP SoluPotasse® Split into (kg) (kg) (kg) (applications)

Planting - 10 - -

Month 1 55 20 40 2 - 3

Month 2 85 40 80 3 - 4

Month 3 140 80 120 4 - 5

Month 4 - 100 200 5 - 6

SoluPotasse® fertigation programme(Planting density from 2000 to 2500 plants/ha)

Every month 75 65 135 5 - 6

From flower initiation to fruit setting

SOP for improved quality

Sulphur, an important secondary element

SoluPotasse® use in tropical fruit production

Different forms of sulphate of potash available from Tessenderlo Group

Imported and distributed by:

Standard SOP: for direct application or for use in the manufacture of compound fertilizers.

GranuPotasse®: a granular grade ideal for bulk blending or for direct application with an even distribution on the soil.

SoluPotasse®: a highly soluble grade for fertigation.

K-Leaf ®: a new fast-dissolving grade specially developed for foliar application.

Tessenderlo Group Rue du Trône 130

1050 Brussels, Belgium Tel: +32 2 639 1811 Fax: +32 2 639 1902

www.tessenderlo.com sopplantnutrition@tessenderlo.com

Tessenderlo Group SOP Plant Nutritiongiving nature a helping hand

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While every care has been taken to ensure that the information in this publication is correct at the time of publication, Tessenderlo Group cannot give any guarantee as to its accuracy nor accept any liability resulting from its use. K-Leaf ®, SoluPotasse® and GranuPotasse® are trademarks of Tessenderlo Chemie NV/SA. ©2014, Tessenderlo Chemie NV/SA. All rights reserved. This material is protected by copyright laws and international treaties.

Any reproduction for distribution is strictly prohibited without the express written permission of Tessenderlo Chemie NV/SA.