Contribution of new and old phosphorus from organic and inorganic fertilizers in subsurface-drained fields using machine learning.
Data files
Jan 12, 2026 version files 212.54 KB
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Raw_Data(New_P_paper0).xlsx
207.68 KB
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README.md
4.86 KB
Abstract
Phosphorus (P) is essential for crop growth but leaches through subsurface drainage discharge, impacting water quality. This study’s objectives are: (1) apply machine learning to quantify the contributions of incidental (new) and legacy (old) P in drainage discharge from Organic site and Inorganic site, and (2) evaluate the effect of manure application timing on P loss. We collected data from two on-farm sites in southeast Michigan, USA. We applied the Weighted Regression on Discharge and Seasons (WRDS) equation to analyze P load based on drainage discharge and fertilizer application timing. The data was divided into calibration and validation sets, and machine learning was employed for training. The results showed strong model prediction performance. Organic fertilizers contributed approximately twice the total phosphorus (TP) loss (7.54 kg ha⁻¹ vs. 3.73 kg ha⁻¹) and nearly four times the dissolved reactive phosphorus (DRP) loss (4.90 kg ha⁻¹ vs. 1.05 kg ha⁻¹) compared to inorganic P loss. When applied during winter months (Dec-Jan), organic fertilizer contributed to greater new P loss, whereas early fall applications (Oct-Nov) resulted in lower new P loss, showing the importance of application timing. At the Organic site, legacy P was the dominant contributor to total phosphorus (TP) and dissolved reactive phosphorus (DRP) losses, accounting for 84% and 79% of losses, respectively. At the Inorganic site, Legacy P was responsible for 97% of TP loss and the entirety (100%) of DRP loss. In conclusion, legacy P was the dominant source of P loss through drainage discharge, and timing of organic fertilizer application significantly influenced new P loss.
Contribution of New and Legacy Phosphorus from Organic and Inorganic Fertilizers in Subsurface-Drained Fields Using Machine Learning
Access this dataset on Dryad
This dataset contains field-scale subsurface drainage, precipitation, and phosphorus load observations collected from subsurface-drained agricultural fields managed with organic and inorganic fertilizer systems. The data support analysis of total phosphorus (TP) and dissolved reactive phosphorus (DRP) transport dynamics, including differentiation between new and legacy phosphorus contributions, and are intended for use in statistical and machine learning–based modeling frameworks.
Description of the Data and File Structure
This dataset consists of a single Microsoft Excel workbook containing time-series observations of hydrologic and phosphorus transport variables measured at two experimental subsurface-drained field sites. The workbook is organized into separate worksheets to distinguish fertilizer management systems and to facilitate comparative analysis between organic and inorganic phosphorus sources.
Files Included in This Dataset
Raw_Data(New_P_paper0).xlsx
This Excel file contains all observed hydrologic and phosphorus load data used in the associated analysis.
Worksheet Structure
- Page 1: Organic Fertilizer Site
Contains data collected from a subsurface-drained field managed with organic fertilizer inputs. - Page 2: Inorganic Fertilizer Site
Contains data collected from a subsurface-drained field managed with inorganic fertilizer inputs.
The separation of worksheets was implemented to maintain clarity between management systems and to avoid ambiguity during analysis and model development.
Variables and Definitions
All variables are consistently defined across both worksheets. Units are provided to ensure reproducibility and proper interpretation.
date
- Description: Calendar date of observation
- Format: MM-DD-YYY
precipitation
- Description: Daily precipitation depth measured at or near the field site (daily)
- Units: centimeters per day (cm)
drainage_discharge
- Description: Daily subsurface drainage discharge from the field
- Units: centimeters per day (cm day⁻¹)
- Represents the volume of water exiting the subsurface drainage system
TP_load
- Description: Observed total phosphorus load exported via subsurface drainage
- Units: kilograms per hectare (kg ha⁻¹)
- Includes both particulate and dissolved phosphorus fractions
DRP_load
- Description: Observed dissolved reactive phosphorus load exported via subsurface drainage
- Units: kilograms per hectare (kg ha⁻¹)
- Represents the bioavailable fraction of phosphorus in drainage water
Notes on Missing and Zero Values
- Days with zero drainage discharge indicate no measurable subsurface flow; phosphorus load values on these days are recorded as null.
- Days with measurable drainage discharge but missing TP or DRP values may result from:
- Autosampler malfunction or data loss
- Phosphorus concentrations, particularly DRP, falling below analytical detection limits
Null values are left unfilled to preserve data integrity and avoid artificial inflation of nutrient loads.
Definitions of Phosphorus Terms
Total Phosphorus (TP)
The sum of all phosphorus forms, including particulate-bound and dissolved fractions, transported in drainage water.
Dissolved Reactive Phosphorus (DRP)
The soluble, immediately bioavailable form of phosphorus that readily contributes to eutrophication in receiving waters.
New Phosphorus
Phosphorus derived from recent fertilizer applications.
Legacy Phosphorus
Phosphorus stored in the soil from historical fertilizer applications that continues to contribute to drainage losses over time.
Sharing and Access Information
This dataset is publicly available through the Dryad Digital Repository.
- Repository: Dryad
- Dataset DOI: 10.5061/dryad.hqbzkh1wm
Data Source
Data were collected from an on-farm subsurface-drained agricultural field site located in Lenawee County, southeastern Michigan, USA.
Code and Software
No executable scripts are included in this submission.
The dataset can be accessed and analyzed using:
- Microsoft Excel
- R
- Python
- MATLAB
- Other statistical or scientific computing environments capable of reading Excel (.xlsx) files
Dataset Readiness Statement
All variables are explicitly defined with consistent units across fertilizer management systems. The dataset is fully documented to support transparency, reproducibility, and reuse in studies focused on phosphorus transport, subsurface drainage, nutrient management, and machine learning–based environmental modeling.