kelp,ca25,K silicate,K nitrate,K sulfate,N3,aminos, fulvic(always). JK
I was reading the nutritech document about Potassium ann came across this little nugget. According to this non-academic article K nitrate did not prove to be as beneficial as other forms. Why do use K nitrate and what do you see? I am trying my best to wrap my head around the function of potassium in different forms.
Potassium Nitrate Proves Counter Productive
New, published research by USDA research scientist,
Dr Gene Lester and his associate,
Dr John Jifon, involved analysis of the benefits of foliar potassium during fruiting and the study also compared various sources of soluble potassium including, potassium sulfate, potassium chloride, potassium nitrate and Mono Potassium Phosphate (MKP). In this comprehensive, multi year, field study (involving rock melons) the researchers analysed differences in petiole K, fruit K, brix levels and total sugars based upon different potassium inputs and a control that did not receive foliar potassium. In each of the three years of the trial, potassium nitrate performed poorly. In fact, it was the worst performer in each year on every parameter. It was even worse than the control in a couple of instances.
Next the researchers compared nutritional value and fruit firmness with the various imputs. They looked at vitamin C, beta-carotene, and fruit colour. Colour is linked to pigments, which are, in turn, antioxidants of considerable nutritional importance for humans. The more intense the colour, the greater the protective capacity of the fruit or vegetable. Again, potassium nitrate was the dismal performer, although it was edged out for the wooden spoon by potassium chloride on a few occasions during the three-year research project.
Finally, the study looked at yield, fruit size and discarded fruit. Here, the negatives associated with the K nitrate input became most pronounced. The yields on the potassium nitrate treated blocks were actually lower than the control in each of the three years of the study and the discards were substantially higher following K nitrate foliars. In fact, there was an average of
three times more throwaway fruit when K nitrate was compared to potassium sulfate and twice the discards in comparison to the controls. This input proved to be seriously counterproductive and yet tens of thousands of growers around the globe religiously foliar spray potassium nitrate throughout the second half of the season. The authors of the study concluded that “potassium nitrate may not be suitable for late season foliar nutrition” and they are most certainly correct. Nitrate nitrogen is for vegetative growth. It does not provide a reproductive push and it can be antagonistic to potassium uptake. Nitrates are always absorbed with water so there is a nutrient dilution factor that inevitably reduces fruit quality. It is hard to imagine a more inappropriate choice for potassium nutrition!
One of the replys
The impact of Potassium is very pronounced on Cytokinin levels and hence fruit size. The application of the nitrate N is thus in contradiction with fruit formation as mentioned as amm-N is also pro CYT. The functional role of K(&Zn) in translocating sugars from source to sink is as important and with increased Nitrates big pressure on Moly levels and if shortage will induce possible ethylene with possible subsequent Absicinic Acid (ABA) and hence leading to senescence and cut-off of CYT and thus fruit formation.