Plant nutrients are essential building blocks of crops. In order to obtain high pome fruit yields it is important to achieve the right balance of fruit number on the tree. Trees with a heavy load will have more disorder problems, because the high numbers of fruits compete for the available calcium. Equally, those with a low fruit load could suffer from calcium dilution problems because fruit size is large. Thus, a correct balance between crop load and fruit size is important.
All crop nutrients must be available to the crop at the required rate and balance.
Crop Nutrition and Pome Fruit Yield
Nitrogen, calcium and potassium are required in greatest quantities by pome fruit crops.
Nitrogen is critical to maximize early season tree, leaf and fruit growth. Typical removal in apple fruit is around 0.6kg of N per ton of fruit annually.
Large amounts of calcium are needed within the tree to support crop production. Most of this is taken up during early periods of growth. Only a small proportion of calcium finds its way into the fruit. As a result, annual crop removal is less than 0.1 kg/t of fruit.
Maximum potassium uptake occurs during the fruit filling stage, and is later than the peak of nitrogen and calcium. It is a key driver to maximize fruit yield and weight with on average 1.4kg removed per tonne of apple crop harvested.
Relatively low levels of phosphorus are used by pome fruit crops and uptake occurs readily throughout the season. Soil supplies can commonly meet needs, however during peak periods of demand, fertigation, foliar, or fruit applications may be necessary.
Magnesium is important to maintain good growth, but removal is low at less than 0.1kg/t of fruit.
It must be ensured that boron, iron, manganese, molybdenum and zinc are also not limiting.