Nutrient deficiency information & photo guide
January 23, 2011 § 2 Comments
Here is a really useful guide I use when identifying nutrient deficiencies in vegetable crops.
I have copied it from our business website, where you can find more of my waffle on growing veg.
This data for nutrient deficiencies are from a paper by Wade Berry at the University of California. The images come courtesy of Dr H Bloom and Dr A Epstein from their 2004 paper entitled Mineral Nutrition of Plants: Principles and Perspectives. Dr Berry’s article can be read at:
Boron deficiencies are most likely to manifest in large heading brassica. Leaves may appear distorted and cauliflower heads stunted, small and bitter with brown patches on them. Borax and organic matter (rich compost) contain boron.
Calcium is used by plants to make cell walls, for root growth, for nutrient uptake and for pollen formation. Deficiency symptoms include browning leaf tips and margins and always occur on new growth. Leaves may curl downwards. Fruit and flower growth may be stunted and leaves may appear twisted. Cabbages, cauliflowers, peppers, tomatoes and celery are most susceptible to calcium deficiency. Liming prior to planting is advised for all of these crops as lime increases calcium levels in soils and raises pH- a low pH can cause calcium to become locked into soils and unavailable to the plant.
A classic symptom of magnesium deficiency is interveinal (between veins) chlorosis (yellowing). This begins in older leaves before spreading to new (younger) growth. As the deficiency progress, affected leaves wither and turn brown, curling downwards and dropping off.
Magnesium is easily leached out of soils and growing media. If potassium is in excess magnesium will be unavailable to the plant.
A foliar feed quickly delivers available magnesium to the plant- results should be visible within hours to days. Liming soil when planting susceptible crops- tomatoes, potatoes, fruit bushes and aubergines- is advised. Consider using Epsom salts to provide magnesium quickly to plants.
Phosphorus is essential for seed germination and root development. It is needed at two distinct stages of growth: young plants undergoing root development and older crops when fruits set and when seeds are produced.
Root vegetables need plenty of phosphorus.
Phosphorus deficiency commonly manifests as a reddish or purple colouration, usually on leaf undersides (purplish stems on tomato seedlings and ‘red’ vegetables like red cabbage or giant red mustard is natural) and stems of corn, brassica, tomatoes and lettuce.
Visible symptoms like leaf yellowing are rare- the most common symptom is slow growth in general and specifically slow growth of flowers and fruits. High levels of plant available phosphorus are found in wool, rock phosphate, bone meal and fish emulsion.
Potassium (or potash) deficiencies manifest as browned, curled leaf margins (‘scorched’), low resistance to disease and poor fruit yields. General vigour is reduced.
Natural sources of potassium include wood ash, greensand, comfrey liquid feeds and rock dust. Potash resides for two to three years in the soil but will need to be supplemented if the same plot is used for vegetables year on year.
Nitrogen is used by plants for leafy growth and formation of stems and branches. Vegetables with very high nitrogen requirements include: Brussel sprouts, cabbages, beetroot, spinach and celery.
Legumes and root vegetables need very little nitrogen. In the case of legumes they produce their own and adding extra may interfere with this process.
Symptoms of nitrogen deficiency include leaf yellowing from the base of the plant upwards and stunted growth. Leaves may be yellower than they should be all over the plant.
Whilst nitrogen is an essential major nutrient, too much of it causes unwelcome problems. Nitrogen build up can occur if manure or fertiliser is applied too regularly. Excess lush soft foliage is particularly attractive to pests and vegetative growth spurts can result in late or no flowering. Too much nitrogen in seedling compost inhibits seed germination.
Sources of soluble organic nitrogen include fish powder, fish emulsion, guano, worm castings, manure and compost teas. Blood meal, feathers, hoof and horn based fertilisers and manure are applied as a top dressing to provide a slow release effect. Nitrogen fixed from legume food crops and cover crops is a preferable source of nitrogen and the most easily absorbed for plants. There is also no risk of leaching, burning or nutrient runoff.
Sulphur deficiencies are uncommon, however they may occur in leached soils and those that have been used intensively for growing crops, especially brassica. Symptoms of sulphur deficiency are similar to those for nitrogen- stunted growth and leaf yellowing. Brassica are most commonly affected.