Have you analysed your soils for micronutrients?
NRM
Agriculture
Between one third and a half of all soil samples tested by NRM are deficient in either copper, zinc or manganese. We see this year after year in our annual soil survey and it is widespread both geographically and by soil type. Although crops only require a small amount of each micronutrient, if there is deficiency in any one of them, yield and margins can be disproportionately reduced. However good the general crop nutrition may be, yield is always determined by the lowest limiting factor and copper, zinc and manganese are the trace elements most deficient in UK soils.
Copper is immobile in the soil and so uptake is dependent on good root development. In the plant it acts as a catalyst for photosynthesis and is a key component of a range of plant enzymes. Copper deficiency results in a general lack of growth and symptoms ranging from leaves losing their colour to being wrinkled and twisted. Leaf tips can dry out and go white with blind ears seen in late season.
Zinc is the most commonly deficient micronutrient. A lack of zinc will lead to fewer grains per ear and potentially poorer grain quality. Deficiencies are most likely on soils rich in organic matter or with a raised pH. High phosphate content will also lock up zinc and deficiencies are often seen in cold wet conditions.
Symptoms of zinc deficiency are most evident in maize crops but can be seen across a wide range of other crops. Typical symptoms are pale yellow chlorotic patches, parallel to the mid rib of the leaf with the youngest leaves at risk of being totally yellow or white. Zinc is required to support good early plant development and, in maize, will contribute to the crop being ready to harvest earlier, which is important to protect soil health.
Manganese deficiency in crops can be found in high pH, high organic matter soils and especially in fluffy seedbeds in the spring. Crops grown on sandy soils where nutrients can be lost easily are also at risk. The key symptom of manganese deficiency is interveinal chlorosis in the younger and central leaves. Manganese is not mobile in the plant, so the younger leaves at the top of the plant are most vulnerable to deficiency. Manganese increases nutrient levels in the crop, improving flowering and evenness of crop maturity as well as promoting winter hardiness and disease resistance.
To optimise crop production, micronutrients can be as important as the macronutrients. A broad-spectrum analysis of soils will identify deficiencies before symptoms are seen, but you can also take plant tissue tests as crop develop during the spring, when remedial action can still be taken.
Even when symptoms are seen, it can be difficult to identify which micronutrient is lacking as symptoms can be very similar. The principle of ‘forewarned is forearmed’ works well in this situation, and soil or tissue analysis will ensure you can make the correct choice of foliar nutrients to rectify problems in the crop and avoid loss of yield at harvest.
Contact your agronomist or farm advisor, or call NRM direct, to arrange for soil samples to be tested for micronutrients, and for tissue testing during the season.
Read more about soil and plant tissue analysis from NRM here.
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