Point of Nutrition

Manuring is an important means of ensuring the healthy growth of fruit plants and of regulating vegetative growth, fruit yield and quality. Each kind of fruit has its own requirements for manures and what is best for plums and black currants will not give the best results for apples, gooseberries and strawberries. This post deals with general principles only and should be read in conjunction with the special recommendations for individual crops.

The main manures for contain nitrogen, phosphate and potash. Potash is of outstanding importance for all fruits, phosphates are not so important for the tree fruits and the needs for nitrogen vary. For example, plums and black currants benefit from heavy dressings of nitrogen, but generous nitrogenous manuring for apples, raspberries and strawberries may make the plants over-vegetative and reduce yield and fruit quality.

A must be kept between shoot growth and fruiting, with the aim of obtaining heavy crops of good quality for successive years. This can only be achieved by careful manuring, combined with other management practices, and in particular by the prevention of mineral deficiencies and excesses.

No fruits are real lime-loving plants, not even the stone fruits. Most prefer slightly acid soil conditions, or soils with only small of free lime in them, whilst some fruits will grow well on strongly acid soils provided they are well manured. The great danger from overtiming arises in the fact that fruit crops are very susceptible to deficiencies of the so-called trace elements, particularly iron and manganese, and in a soil of high lime content these two elements may become unavailable to the plant.

A first principle in growing fruits should be to avoid highly calcareous soils and to be sparing in applying lime. Lime should only be applied if the soil is very acid.

The second point to stress is the importance of organic matter in fruit soils. Fruit plants must have a free-rooting medium for healthy growth and longevity, and this can be assured only by maintaining a good content of organic matter. For tree fruits such as apples and pears, this may be best achieved by growing the trees in grass after the first 3 or 4 years in clean cultivation, or by dressings of bulky composts or manures used as surface mulches. The grass and other organic materials must be kept clear of the tree trunk. For the usual method is to dig in bulky manures or compost before planting.

It is usually necessary to use concentrated organic manures or inorganic fertilisers in addition to bulky manures to supply the right amount of nutrients needed. Any of the usual manures and fertilisers used for other crops are suitable, though a few precautions are necessary in some cases to avoid injury. All chloride-containing fertilisers, such as muriate of potash, should be used with caution, or not at all, on soft fruits, particularly red currants. Manures and fertilisers should be applied to the soil, and late winter and early spring – February and March – are the best times to apply them.

Excessive manuring, especially with nitrogen, is shown by over-vigorous growth, large dark green leaves, poor fruiting or large, poor-quality fruits.

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