hope you dont mind found some interesting reading what are your thoughts on this
In hydroponics, standard quantities of NH4+ added to nutrient solutions for soilless culture are between 5 and 10 % of the total N supply and seldom will exceed 15 %. For rose it tends to 25 % during the vegetative stage, whilst for melon it tends to 0 % during fruit development, for example. The tuning of the NH4+ addition merely occurs during crop growth in relation with the pH development in the root environment. Addition of NH4+ lowers the pH in the root environment, because of an activation of the cation (NH4+) uptake and a reduction of the anion (NO3-) uptake. When NH4+ is taken up, the plant releases H+ in order to maintain the plant’s electrical neutrality, which causes a lower pH in the root environment. Optimum pH levels in the substrate solutions range from 5 to 6 for almost all crops.
Addition of NH4+ as a replacement of NO3- in substrate systems can reduce the uptake of other cations, like K+, Ca2+ and Mg2+, which can be explained by cation competition of NH4+ and these cations. The proportion of these effects depends of different factors like crop, growing conditions and the adjustments made in the ionic balance of the nutrients. Therefore, a careful use of NH4+ is recommended for crops which are sensitive to Ca deficiency. This is especially true when such crops are grown under climatic conditions that reduce the Ca transport to fruits. Good examples of this are the production of tomato and sweet pepper under dry and hot conditions. Both crops are sensitive to blossom-end rot, caused by Ca deficiency in the fruit, which is stimulated by a hot and dry climate. Under such conditions every reduction in Ca uptake becomes dangerous and thus, the use of NH4+ too
Advantages of nitrate over ammonium-containing fertilisers
Nitrates are the preferred nitrogen source:
Non-volatile: unlike ammonium, nitrate is non-volatile, so there is no need to incorporate it in the soil when applied by top- or side dressing, which makes it a convenient source for application.
Mobile in the soil - direct uptake by the plant, highest efficiency.
Nitrates synergistically promote the uptake of cations, such as K, Ca and Mg, while ammonium competes for the uptake with these cations.
Nitrates can be readily absorbed by the plant and do not need to undergo any further conversion, as is the case with urea and ammonium, before plant uptake.
No acidification of the soil if all the nitrogen is applied as nitrate-nitrogen.
Nitrates limit the uptake of harmful elements, such as chloride, into large quantities.
The conversion of nitrates to amino acids occurs in the leaf. This process is fuelled by solar energy, which makes it an energy-efficient process. Ammonium has to be converted into organic N compounds in the roots. This process is fuelled by carbohydrates, which are at the expense of other plant life processes, such as plant growth and fruit fill.
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