Sustainable fertilization management requires a true shift in mindset—one where the role of the agronomic advisor becomes essential. Spain’s new regulatory framework (Royal Decree 1051/2022) not only mandates planning and documenting every nutrient application, but also places emphasis on understanding soil as a living ecosystem in which biology is just as important as chemistry.

In this context, microbial biofertilizers such as Bulhnova—formulated with Azospirillum brasilense M3 and Pantoea dispersa C3—represent a proven technical alternative. They allow growers to reduce mineral fertilizer inputs, improve soil structure and function, and enhance resilience to climatic stress.

Multizone field trials with Bulhnova, conducted on different crops and soil types, have demonstrated the ability to reduce mineral fertilizer use without affecting fertility or yields, while increasing total nitrogen, available phosphorus, and microbial biodiversity.

These results reinforce the value of technical knowledge and field-based decision-making by qualified professionals. Their expertise is essential for translating soil science into efficient, sustainable farming practices adapted to climate change.

A new regulatory framework and the advisor’s role

Royal Decree 1051/2022 requires all nutrient inputs to be recorded in farm management logs, and mandates that every production unit have a fertilization plan aimed at maintaining or increasing soil organic matter.

The regulation prioritizes the use of organic and biological fertilizers, requires emissions-reduction measures, and assigns responsibility to certified “fertilization advisors,” who guide implementation of nutrient plans where Bulhnova fits naturally.

This structure aligns with North American models: Pest Control Advisers (PCA) in California—regulated by the California Department of Pesticide Regulation—and Certified Crop Advisers (CCA), under the American Society of Agronomy.

Both roles act as licensed professionals responsible for nutrition and plant health decisions, ensuring that agronomic recommendations are justified, sustainable, and traceable.

In the United States, the Nutrient Management Specialist is now a key function within the CCA program, integrating soil data, microbial activity, and nutrient status into a unified technical strategy.

Importantly, no agricultural product is applied without a formal recommendation from these advisory figures.

Royal Decree 1051/2022 moves in the same direction: shifting responsibility away from fertilizer distribution and toward knowledge management, acknowledging that soil decisions must be interpreted by qualified agronomists.

Degraded soils and results after Bulhnova application

Years of agricultural intensification have led to soil degradation, reduced organic matter, compaction, and nutritional imbalance.

In response, microbial consortia that combine nitrogen-fixing and phosphorus-solubilizing bacteria are becoming a viable technical solution—one that requires expert interpretation to apply effectively in real-world conditions.

Probelte is a pioneer in Spain in using this type of biological tool. More than twenty years of experience began with its first biofertilizer, Bioprón, later evolving into new formulations such as Bulhnova and Bulhnova SP.

In trials across several seasons on sandy-loam, clay-loam, and silty-clay-loam soils, the consortia A. brasilense M3 and P. dispersa C3 enabled nitrate reductions from 90 mg/kg to around 60 mg/kg, while increasing total nitrogen by an average of 15%, available Olsen phosphorus by 20%, and exchangeable potassium by 10%—compared to conventional mineral programs.

Biological indicators showed greater microbial diversity (Shannon Index) and less dominance (Berger-Parker Index), confirming a more balanced and functional microbial community than in conventionally managed soils.

These results align with documented mechanisms associated with plant growth-promoting rhizobacteria (PGPR): biological nitrogen fixation, phosphorus solubilization, siderophore production, phytohormone synthesis (IAA), and hydrolytic enzymes that improve porosity and cation exchange capacity (Gufwan et al., 2025; Valente et al., 2025; Prasad et al., 2014).

Under semi-saturated soil conditions, Azospirillum brasilense maintains microanaerobic performance, while Pantoea dispersa shows strong rhizosphere colonization, releasing phosphorus and bioactive compounds (Chen et al., 2014).

Backed by scientific evidence and technology, it is the agronomic advisor who interprets results and adapts them to each crop and operational context.

Experience from regenerative agriculture farms confirms that biofertilizers are most effective when advisors integrate soil fertility indices—including enzymatic activity, organic matter, available phosphorus, exchangeable potassium, EC, pH, soil metagenomics—and adjust irrigation and application strategies accordingly.

Artificial intelligence tools improve accuracy and efficiency in agronomic decision-making, but their true value emerges when advisors use them directly—turning data into tailored, real-world decisions.

Their knowledge of the field, crop history, and operational priorities ensures that technology is applied with precision and impact, reinforcing the advisor’s role as a central pillar in sustainable agricultural management.