Well, the answer to this question depends on the interaction of multiple variables such as pH, temperature, and the effect of the form of N on the other nutrient ions. Good news is that whatever form suits you best is available at PULCU TARIM.

Plants require nitrogen (N) for growth, development, yield, and defense against abiotic and biotic stresses. Nitrate and ammonium are predominant forms of inorganic nitrogen absorbed by plant roots. Ammonium and nitrate as different forms of nitrogen nutrients impact differently on some physiological and biochemical processes in plants.

There is controversy about the relative advantage of one form over the other in terms of various physiological processes or plant species. Compared to nitrate, ammonium results in a small leaf area, high specific leaf weight, and low leaf area ratio due to reduced osmotic regulation. Growth responses over a wide array of environments, especially low light intensity, are usually superior for  than for NH4+.

NH4+ is a cation and NO3- is an anion, and in negatively charged soil particles, NH4+ is bound, while NO3- remains mobile. Hence, NO3- can move with the soil solution to the root or be more readily leached from the soil.

Relative to  NO3- nutrition,   NH4+ nutrition requires less energy.

 NO3- nutrition per se is not toxic and can be stored for future use in various organs such as stalk of a maize.

Uptake of   NH4+ and NO3- are affected differently by the temperature and pH of the soil. For NO3- uptake, a soil pH of 4.5 to 6.0 is considered optimal. While a pH of 6.0 to 7.0 is best for NH4+. They are both temperature dependent.

Young plants absorb NH4+ more readily than NO3- ; however, as the plant ages, the converse is observed.

Either NO3-  or NH4+ salts can serve as an adequate source of N for plant growth, but, in general,  salts are considered the “safer” fertilizer for plant production. Nevertheless, calcifuge (acid-loving) plants that grow naturally in acid soils where little nitrification occurs utilize  in preference to . In contrast, calcioles (plants with a wide pH tolerance) preferably utilize .

Mixtures of NH4+ and NO3- salts provide the most suitable source of inorganic N for asceptically cultured cells.

Ammonium was reported to be superior to nitrate for the growth of blueberry, rice, sweet pepper, and maize. In contrast, ammonium supplied as the sole nitrogen source inhibits growth compared to nitrate nutrition or a mixture of nitrate and ammonium.

Ammonium inhibits root growth, resulting in higher shoot/root ratio compared to nitrate nutrition or the mixture of nitrate and ammonium in wheat, sugar beet, maize, beans, and tomato plants.

Higher losses of carbon through root and leaf respiration were found with ammonium than with nitrate. A higher fraction of root carbon is used in ammonium absorption and assimilation, and the losses of organic carbon are due to differences between ammonium and nitrate in the metabolism of absorption, assimilation, transportation, and energy cost.

In leaves, nitrate is reduced to nitrite by nitrate reductase (NR) in the cytosol, and nitrite is reduced to ammonium by nitrite reductase (NiR) in the chloroplast, where the subsequent assimilation of the ammonium into glutamate by glutamine and glutamate reductase (GS/GOGAT) occurs.

Growth on NO3- nutrition leads to increased levels of NO, SA, PR gene expression, induction of the polyamine pathway, a decrease in apoplastic sugars and amino acids, and an overall increase in plant resistance in a concentration-dependent manner.

Growth on NH4+ nutrition leads to increased levels of apoplastic sugars and amino acids, reduced levels of SA and PR gene expression, induction of GABA biosynthesis and reduced plant defense response.


Nitric oxide (NO) is a vital signaling molecule that mediates key physiological events such as senescence, flowering, development, germination, photosynthesis, and the efficiency of both photosystems and plant–water relations under abiotic stresses. NO is regulated as ion homeostasis in plants under salinity and other abiotic stresses. NO-strengthened antioxidant activities diminish oxidative damage in plants. The uptake of heavy metals such as cadmium (Cd), lead (Pb), and nickel (Ni) is significantly lower in plants with greater endogenous NO levels.

γ-Aminobutyric acid (GABA), four-carbon non-protein amino acid, is well recognized as an endogenous plant signaling molecule and involved in various physio-biochemical processes of a plant. GABA is an endogenous signaling molecule and involved in growth regulations and plant development.

Salicylic acid (SA) is an important plant hormone and well-studied endogenous plant growth regulator that generates a wide range of metabolic and physiological responses in plants involved in plant defense in addition to their impact on plant growth and development.

Polyamines are known to play a wide role in plant physiological processes helping them in differentiation, inducing totipotency, increasing cell division and also in molecular signaling.

The extracellular space (apoplast) of plant tissue is a nutrient-rich niche and many microbial pathogens have evolved strategies to cause infection in this compartment. For their optimal multiplication, pathogens ensure the uptake of sugars and other required metabolites from the apoplastic compartment.

PR gene, Pathogenesis-related (PR) proteins, are proteins produced in plants in the event of a pathogen attack. They are induced as part of systemic acquired resistance. Infections activate genes that produce PR proteins.


Guo, S., Zhou, Y., Shen, Q., & Zhang, F. (2007). Effect of ammonium and nitrate nutrition on some physiological processes in higher plants-growth, photosynthesis, photorespiration, and water relations. Plant Biology9 (01), 21-29.

Hageman, R. H. (1984). Ammonium versus nitrate nutrition of higher plants. Nitrogen in crop production, 67-85.

Mur, L. A., Simpson, C., Kumari, A., Gupta, A. K., & Gupta, K. J. (2017). Moving nitrogen to the centre of plant defence against pathogens. Annals of botany119 (5), 703-709.


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