Imagine taking soil samples from two ends of the same field and sending them to a lab. Since it’s the same parcel, you’d expect the results to come back similar, but more often than not they don’t. One side is clayey and holds water for a long time, the other is sandy and lets it go quickly.
Organic matter, pH, phosphorus and potassium levels can also vary within a single parcel. Even so, fertilization programs are usually built as one calendar for the whole field: base fertilizer on this date, top dressing at that growth stage, another application after that.
There’s a logic to this habit. A calendar makes production easier to plan, bringing growth stages, climate and the order of work into one picture. What it can’t tell you is what the plant needs today. That answer lies in the soil, the root zone, the water and the plant itself.
In his 2021 study “Site-Specific Nutrient Management,” Witold Grzebisz of the Poznań University of Life Sciences argues that the work should begin by determining soil fertility in the root zone and the nutrients the plant can actually reach. According to the study, nitrogen supply and demand don’t vary only over time. They also vary across different points in a field and at different soil depths. If not every part of a field is the same, it isn’t realistic to expect the same program to give the same result everywhere. So a good program has to answer more than “which fertilizer, on which date.” It also has to answer where in the field, how much, and what condition the crop is in right now.
A 2022 study by Joost van Heerwaarden of Wageningen University points in the same direction. It is a theoretical assessment for maize in sub-Saharan Africa. It shows that soils can differ considerably in their capacity to supply water and nutrients, and that adjusting fertilizer to those differences has the potential to bring economic benefits. The goal isn’t to make the field needlessly complicated, but to stop ignoring the differences that are already there. In one spot, the phosphorus available to the plant may be sufficient while in another it falls short. Applying the same amount everywhere is easy, but it won’t meet the plant’s needs equally at every point.
This approach hasn’t stayed in academic papers. The EU-supported NUTRI-CHECK NET project worked with farmers and experts across many countries, from Denmark to Greece and the Netherlands to Portugal, between 2023 and 2025. In the project’s own words, the core idea is “measure to manage”: make nutrition decisions at field and farm level, and test the available decision support tools in practice while doing so.
Phosphorus shows that there is no single recipe either. A study published in Environmental Sciences Europe in 2025 examined phosphorus fertilization and its use efficiency in Europe between 1990 and 2021. It found major differences between countries in both intensity and efficiency. In low-intensity systems, a controlled increase can benefit yield. Where intensity is already high, reducing inputs may be the more sustainable direction. Topping up a shortfall can be the right move in one place, and the same application can turn into a needless surplus in another.
One of the most widely used frameworks in nutrient management is 4R: right source, right rate, right time, right place. The four can’t be considered separately. If you pick the right fertilizer but apply more than the crop needs, the rate is wrong. If you calculate the right rate but apply it when the plant doesn’t need that nutrient, part of it can be lost before it ever reaches the crop. The shared conclusion of the reviews is that matching the plant’s demand as closely as possible with what the soil and the fertilizer supply, in timing as well as amount, improves the balance between yield, cost and environmental losses.
A 2021 meta-analysis by Chivenge and colleagues compared site-specific nutrient management with farmers’ usual fertilization practices. It evaluated 61 studies from 11 countries, covering maize, rice and wheat. Site-specific practices were associated with 12% higher grain yield and 15% higher profitability on average. In addition, they were associated with 10% less nitrogen fertilizer use on average, and agronomic nitrogen use efficiency was found to be about 40% higher.
It’s worth remembering that these figures come from maize, rice and wheat studies. They can’t be carried over as-is to an orchard, a vegetable field or a greenhouse in Turkey. Still, the direction is clear: better nutrition doesn’t mean applying more fertilizer.
Collecting data about soil and plants has become far easier. A 2025 review covering 97 studies from 2013 to 2024 shows that electrochemical sensors and spectroscopy are being studied intensively, and that remote sensing, data analysis and machine learning are increasingly used in nutrient management. The same review also points out a limit: today, no single sensor or method can measure all soil properties and nutrients perfectly. Which one works depends on what you want to measure and on the conditions. Technology is a tool that strengthens the data a decision rests on. The last word still belongs to soil analysis, crop observation, field experience and sound interpretation.
None of this means giving up the fertilization calendar. Knowing growth stages, following the climate and timing applications well remain a core part of production. What changes is that the calendar no longer decides on its own. Add soil analysis, root zone conditions, leaf analysis, water status and field observations, and the program moves from guesswork to measurement. The question “which fertilizer should I apply on this date?” gives way to “what does this crop, in this field, need right now?”
References
Grzebisz, W. (2021). Site-Specific Nutrient Management. Agronomy, 11(4), 752. DOI: 10.3390/agronomy11040752.
Szymańska, M., Sulewski, P., Wąs, A., et al. (2025). In the way to more sustainable phosphorus management in European agriculture: changes in fertilization efficiency in the context of the sustainable intensification concept. Environmental Sciences Europe, 37, 235. DOI: 10.1186/s12302-025-01251-1.
van Heerwaarden, J. (2022). The theoretical potential for tailored fertilizer application. The case of maize in Sub-Saharan Africa. Field Crops Research, 288, 108677. DOI: 10.1016/j.fcr.2022.108677.
Chivenge, P., Saito, K., Bunquin, M. A., Sharma, S., & Dobermann, A. (2021). Co-benefits of nutrient management tailored to smallholder agriculture. Global Food Security, 30, 100570. DOI: 10.1016/j.gfs.2021.100570.
Vullaganti, N., Ram, B. G., & Sun, X. (2025). Precision agriculture technologies for soil site-specific nutrient management: A comprehensive review. Artificial Intelligence in Agriculture, 15, 147–161. DOI: 10.1016/j.aiia.2025.02.001.
NUTRI-CHECK NET. The NUTRI-CHECK NETwork to maximise site-specific precision in managing the nutrition of European arable crops. European Commission / EU CAP Network.
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