The Potash Development Association (PDA) is highlighting the need for all winter crops to receive adequate potash applications now, if this issue had not been addressed  at time of planting.
According to the PDA, potassium (K) significantly affects the strength of straw through its influence on lignification and cell wall thickness.
Any deficiency of potash will reduce straw strength and increase the risk of lodging. This is illustrated by PDA measurements in wheat crops at different levels of potash application over a number of years.
It is also essential that to get the best from the use of plant growth regulators (PGRs) a crop must not be suffering from a lack of potash.
On soils with low potassium reserves, it is recommended that potash fertilisers are incorporated into the seedbed.
If for some reason this has not been done, and winter-sown crops have not yet received a dressing of potash, it is still beneficial to top-dress with potash in the early spring rather than to omit the dressing altogether.
Soils with adequate levels can be dressed at any convenient time, with an application designed to replace the nutrient removed in the crop: in other words a ‘maintenance dressing’ to maintain the soil K reserves.
The penalties associated with potash deficiencies are numerous, with all leading to serious reductions in crop gross margins.
Thy include serious yield loss, especially in adverse growing conditions – particularly dry summers. Weaker growth levels within a crop will result in a higher lodging risk.
Insuffcient potash availability will lead to crops having lower tolerance to physiological stress such as wet, drought, frost, and wind.
In addition, lower crop vigour creates greater susceptibility to disease, pests and weed competition.
Potash deficiencies also create problems where grain and crop quality are concerned. These include poor grain samples; low grain size; and poor specific and 1000 grain weights. The adverse effect on marketability that such issues can create is obvious
Low potash availability will also lead to inefficient nitrogen uptake and utilisation. This leads to poor nitrogen response and less protein synthesis.
When applying potash fertilisers, it is always necessary to ensure that the right balance with phosphate is created in order to deliver optimal crop production levels.
Numerous trials have also confirmed the strong linkage that exists between potassium and sulphur metabolism.
Sulphur availability is a determinant of protein production within all plants. The nutrient must be available in sufficient quantity in order to meet a crop’s requirement in full.
