NFert

N, P and K fertilization following Emilia-Romagna DPI 2026

Overview

NFert is an R package for calculating nitrogen, phosphorus and potassium fertilization requirements in field and tree crops following the Disciplinari di Produzione Integrata (DPI) Emilia-Romagna (ed. 2026). It implements both the method of the balance (Allegato 2) and the Scheda a dose Standard method, mirroring the official Fert_Office tool (v1.26, Febbraio 2026). It supports maximum allowed doses (MAS), soil texture grouping, Olsen P and exchangeable K availability, fertilization distribution planning (organic + mineral), end-of-cycle soil P and K estimation and precision agriculture (NDVI-based variable rate).

Normative reference

• DPI Emilia-Romagna (2025–2026) – Norme Generali; Allegato 2 (metodo del bilancio), Allegati 3, 4, 6, 7, 9; Guida alla Fertilizzazione Minerale e Organica (N, P, K)
• FertDPI / Fert_Office – strumento regionale; NFert riproduce la logica del bilancio azotato per uso in R
• Reg. reg. 2/2024 – limiti MAS (Allegato 9); Reg. reg. 3/2017 – utilizzazione agronomica degli effluenti e del digestato
• Direttiva Nitrati (91/676/CEE) – in ZVN limite 170 kg N/ha/anno da effluenti zootecnici; Reg. UE 2021/2115 (soglie minime efficienza)

Features

• Nitrogen balance (Allegato 2): N_balance() with A (crop demand), B1/B2 (soil fertility), C1/C2 (leaching), D (immobilization), E (previous crop residues), F (previous years’ organics), Forg (current year organics), G (natural deposition). Supports soil_seeding = "no-till" (−3 kg/ha on b1), greenhouse = TRUE (+2 on D), automatic fold of negative E into D.
• Phosphorus balance: P_balance() with Olsen P classification (classify_P_olsen()), Arricchimento / Mantenimento / Riduzione strategy, texture-dependent weight at 30 cm and P immobilisation factor 1.6.
• Potassium balance: K_balance() with K availability class by texture (classify_K()), clay-driven leaching (K_leaching_by_clay()).
• Scheda a dose Standard: scheda_N() and scheda_PK() with the DPI 2026 catalogue of decrements and increments and MAS cap on N.
• Fertilization distribution plan: plan_distribution() combines organic matrices (with DPI 2026 N efficiency by soil × dose × sector) and mineral fertilisers (146-entry concimi.table), returns Eccesso/Deficit alerts and ZVN 170 kg N/ha check.
• End-of-cycle soil dotation: estimate_soil_P_end_of_cycle() and estimate_soil_K_end_of_cycle() for next-year planning.
• Soil chemistry: classify_pH(), classify_carbonate_tot(), classify_carbonate_att(), classify_CEC(), ratio_Mg_K(), ratio_K_CEC(), classify_SOM(), max_SO_input().
• MAS (Massimali): get_MAS() and check_MAS() for maximum allowed N per crop (DPI 2026, RR 2/2024).
• Precision agriculture: NDVI-based variable rate (calibration curve and Holland & Schepers).

Installation

# Install from GitHub (once available)
# devtools::install_github("yourusername/NFert")

Quick Start

library(NFert)

# Calculate nitrogen balance for a maize crop
maize_n_balance <- N_balance(
  expected_yield_tons_ha = 15,
  crop = "Mais trinciato (classe 700)",
  ccp = "Spring-summer crop 100–130 days",
  sand = 50,
  clay = 35,
  Ntot = 1.2,
  SOM = 1.2,
  CN = 9.5,
  oxygen_availability = "Normal",
  winter_rain = 160,
  start_spring_rain = 40,
  prev_crop = "Winter cereals straw removal",
  source = "Cattle slurry",
  fertorg_frequency = "every year",
  location = "Plain adjacent to urbanized areas",
  forg_quantity = 100
)

print(maize_n_balance)

Main Functions

• N_balance(): Main function for calculating comprehensive nitrogen balance
• calc_crop_N_demand(): Calculate crop nitrogen requirements
• soil_fertility(): Estimate soil nitrogen availability
• leaching_loss(): Calculate nitrogen leaching losses
• calc_N_immobilization_loss(): Estimate nitrogen immobilization
• organic_fertilization(): Calculate nitrogen from organic fertilizers
• natural_contribution(): Estimate natural nitrogen deposition
• tri2() and tri3(): Soil texture classification (USDA; tri3 maps to DPI groupings)
• get_MAS() and check_MAS(): Maximum allowed doses (MAS) per crop (DPI 2026)
• calculate_N_fertilization(): Final N dose from balance result
• estimate_N_rate_from_calibration_curve(): NDVI-based rate estimation (calibration method)
• estimate_N_rate_from_holland_schepers(): NDVI-based rate estimation (H&S method)

Nitrogen balance (DPI Allegato 2)

N da apportare = A + C + D − B − E − F − G

• A: Fabbisogno della coltura (resa × coefficiente asportazione)
• B: Fertilità del suolo (N mineralizzabile dalla S.O. + N pronto)
• C: Perdite per lisciviazione (C1 autunno-inverno, C2 fine inverno)
• D: Immobilizzazione e dispersione
• E: N da precessione colturale (residui, leguminose, paglie)
• F: N da fertilizzazione organiche anni precedenti
• G: Apporti naturali (precipitazioni)

NFert computes the balance and then subtracts current-year organic N (Forg) to give the mineral N to apply. In Nitrate Vulnerable Zones (ZVN), the 170 kg N/ha/year limit from livestock effluents applies at farm level.

Documentation

See the package vignette for detailed examples and usage:

vignette("NFert")

Authors

• Michele Croci (maintainer)
• Manuele Ragazzi
• Giorgio Impollonia
• Stefano Amaducci

Citation

To cite this package in publications, use:

citation("NFert")

License

This package is licensed under the MIT License. See LICENSE file for details.

Contact

For questions or issues, please contact: - Email: michele.croci@unicatt.it - Department: Department of Sustainable Plant Productions (DI.PRO.VE.S), Catholic University of the Sacred Heart