Although Nitrogen, Phosphate, potash and sulphur are the four main nutrients applied to agricultural crops, they are not necessarily the only nutrients that may be limiting yield. The law of the minimum states that a crop can only grow to its most limiting factor, which can be any nutrient, or it could simply be soil conditions or growth factors. Micronutrients are fundamental to profitable farming.

Cropkare contains the secondary nutrients and trace elements that are essential for healthy crops and livestock.


Sulphur is probably the most discussed nutrient. It is essential for protein metabolism and the functioning of enzymes. With environmental clean up the deficiencies first seen in the 1970’s are now common, especially on oilseed rape and other brassicas. A deficiency of sulphur will show as a failure to respond fully to nitrogen. The deficiency symptoms in plants are similar to nitrogen symptoms with yellowing of leaves, however sulphur deficiency occurs on the younger leaves first. The flowers of oilseed rape may appear paler or white. The plant requires sulphur in the sulphate form and not elemental sulphur, throughout March, April and May. Improving nitrogen utilisation by correcting the sulphur deficiency will help produce better quality silage with higher ME values. Cropkare contains typically 5% SO3, so a 500kg/ha application would supply 25kg SO3/ha.

Until recently, crops and grass were well supplied with sulphur from lower concentration fertilisers and from deposition from the air. Changes to fertiliser production and reduction in sulphur emission from industry now leave many crops deficient in sulphur. Second cut silage and oilseed rape are particularly demanding and were the first to suffer. Now deficiencies are also found in many other crops, particularly cereals and vegetables.

Cropkare contains around 5% SO3 so every 100 kg/ha applied supplies 5 kg SO3/ha. A typical application of 500 kg/ha would supply around half of the sulphur needed by a high yielding cereal or first cut silage.


Calcium is immobile in plants and is required for cell walls and biological membranes, increasing the mechanical strength of the plant. It also stimulates root and shoot development, as well as having a quality benefit in some crops like potatoes. Problems from soil calcium content as such are rare as calcium is the major element controlling soil pH. The soil pH is far more important in the overall nutrition of plants than the soil content of calcium. There is a proven financial penalty on most crops when the pH falls below 6. Deficiencies can be seen as distortion of young leaves and brown spots in fruits or tubers. Cropkare contains typically 29% CaO, with a neutralising value of more than 25%.


Magnesium is very important in plants as it is the central atom in the chlorophyll molecule and is therefore actively involved in photosynthesis. Magnesium also helps in protein synthesis and the activation of many enzyme systems. Deficiency symptoms are always seen on the older parts of the plant first giving young tissue priority. Typical symptoms are intervenal chlorosis, with leaf veins standing out as bright green. Low levels of magnesium can cause foliar symptoms without reduction in yield, although yield loss has been found in severe deficiency in sugar beet and potatoes. In grass however a deficiency does not affect the yield of grass, but it can lead to magnesium deficiency in stock eating the grass. Cropkare typically contains 6% MgO, so a 500kg/ha application would supply 30kg MgO/ha.

Magnesium is essential for all crops and grass. A good supply of magnesium is essential for livestock and a deficiency can lead to grass staggers or hypomagnesaemia.

Cropkare contains around 6% MgO so every 100 kg/ha supplies 6 kg MgO/ha. A typical application of 500 kg/ha would supply 30 kg MgO/ha to help maintain soil reserves.


Adding sodium in the fertiliser on grass that is used for grazing livestock has been shown to:

• Improve digestibility of grass
• Increase grass growth rate
• Improve milk yields and quality in cows
• Enhance grass palatability resulting in longer grazing times and improved intakes.

Due to inadequate levels of sodium in UK grassland together with high losses in the milk, lactating dairy cows are particularly prone to sodium deficiency, when out at grass.

This essential nutrient, vital for both the health and productivity of the animal, can be effectively applied in grassland fertiliser to raise herbage concentration and supply the grazing cows full sodium requirement.

Sodium is more effective in improving milk yields when applied directly to grass compared to sodium containing feed concentrates, Cropkare contains typically 2.3% Na2O.

Sodium is beneficial to some crops – sugar beet, carrots, celery – and is essential for livestock. Often, herbage provides too little sodium and grass palatability and nutritional value suffer.

Cropkare contains around 2.3% Na2O so every 100 kg/ha contributes 2.3 kg Na2O/ha to the needs of crops and livestock.