Dear colleagues, greetings to all!

This is indeed a very interesting question and, of course, it requires a thorough study, justification, and probably a specific interpretation.

First of all, it is necessary to clearly understand what should be taken as 100% in the case of calculating the efficiency of macroelement use from fertilizers. An essential condition is to account for the residual effects of both organic and mineral fertilizers applied in previous years (possibly 2–3 years back).

It is evidently possible that conditions may form in the soil and its surrounding environment, interacting with the crop (in the control year), which influence these dynamics. Hypothetically, under conditions of a sharp deficiency of applied macroelements (or systematic shortage!?), a deficit may occur, resulting in the formation of crop biomass that utilizes more than 100% of the applied active substance (based on calculations or direct uptake measurements). This may happen when increased mineralization of soil organic matter releases an additional amount of mobile forms of macroelements, which then “participate” in biomass accumulation by the crop. The separate pools of applied and “mineralized” active substances must be clearly distinguished in any such calculations.

However, it should be clearly understood that under natural conditions, it is practically impossible to “force” nutrient uptake by plants (even when using special substances – stimulants and the like). In this case, effective control over plant nutrition also becomes problematic. Moreover, the fundamental laws of agriculture have not yet been refuted.

There is also a critically important issue: when macroelements are taken up from the soil, it results in the mobilization (and depletion) of its internal resources, which leads to a decline in its natural fertility. Therefore, planning such research today appears to be quite complex. Such studies should be long-term (3–4 crop rotations, 10–12 years) to obtain all necessary answers to numerous challenging questions. Over this period, the soil will fully adapt to new treatments (humates, stimulants, etc.), and most importantly, it will provide an answer regarding the stabilization (or loss) of SOC over time through direct measurement of its values (!).

I have not encountered any convincing studies on this topic.

Sincerely, Petro Trofymenko

@ Mutsa, No, it is not possible to get more than 100% use efficiency of NPK due to the following reasons:

1. Some nutrient will definitely lost to the environment and may converted to gasses or leached to the groundwater.

2. Plants can only take up their required nutrients for the growth and development and excess amount may remain in the soil.

3. Many soil factors like pH, texture, nutrient availability also affect the utilization of plant nutrients efficiency.

4. Precision farming or nano-fertilizer use technique may improve the fertilizer use efficiency but they cannot eliminate all losses.

Of course, this is unreasonable, as the efficiency of mineral fertilizers, nitrogenous, phosphate, and potassium, because they are added to the soil in the form of soluble salts, does not exceed 50, 20, and 40% for the aforementioned fertilizers, respectively, for many reasons, the most important of which is the presence of carbon and the high or low acidity of the soil.

regards

this is not correct because the source of N uptake by plant was not identified depending on total-N uptake but the use of isotope dilution technique 15N or 32P you can identify accurately the portion of nutrient gained from fertilizer and then estimate the FUE% using specified equations

Bonsoir!

Il me semble que les rendements de cultures n'atteignent pas les 100%. L'optimum ne dépasse rarement les 90%. Les fertilisations: azotée, potassique, phosphorée sont utiles et parfois indispensables car elles améliorent la production agricole.