soiltillr 0.1.0

Initial CRAN release

New functions

Validation

• validate_soil_data() — checks a data frame for missing columns, negative values, missing rows, and implausible year values before passing it to any analysis function.

Tillage analysis

• summarise_tillage() — computes year × field summary statistics including number of operations, mean depth, maximum depth, total depth, and dominant operation type.
• tillage_depth_trend() — calculates the year-on-year change in mean tillage depth per field and classifies each year as "baseline", "increasing", "decreasing", or "stable".
• detect_compaction() — estimates compaction risk ("high", "moderate", "low") and plow pan depth from tillage records, using a user-specified depth threshold (default 20 cm).

Erosion analysis

• track_erosion_depth() — tracks annual erosion depth, year-on-year change, and cumulative erosion loss per field; classifies trend as "baseline", "improving", "worsening", or "stable".
• estimate_soil_loss() — estimates soil loss in t/ha using a standard mass-balance formula with an optional slope correction via the McCool et al.
  1987. simplified LS factor: LS = (slope% / 9)^0.6.
• compare_fields() — produces a wide-format year-by-year comparison of erosion depth and organic matter between two or more fields, including absolute difference columns.

Visualisation

• plot_tillage_timeline() — line plot of mean annual tillage depth by field.
• plot_erosion_trend() — line plot of annual erosion depth by field, with an optional second panel showing cumulative erosion (show_cumulative = TRUE).
• plot_om_trend() — line plot of soil organic matter (%) by field with a 3.5% reference line.
• plot_tillage_erosion() — dual-panel ggplot2 figure comparing mean tillage depth and erosion depth side by side.

Built-in datasets

• tillage_operations — 20-row hypothetical tillage records for Field_A and Field_B across 2018–2023 (6 variables).
• erosion_profile — 12-row hypothetical annual erosion and soil health measurements for the same fields (8 variables).

References

• Lal, R. (2001). Soil degradation by erosion. Land Degradation and Development, 12(6), 519–539. https://doi.org/10.1002/ldr.472
• McCool, D. K. et al. (1987). Revised slope steepness factor for the USLE. Transactions of the ASAE, 30(5), 1387–1396. https://doi.org/10.13031/2013.30576
• Renard, K. G. et al. (1997). Predicting Soil Erosion by Water: A Guide to Conservation Planning with the Revised Universal Soil Loss Equation (RUSLE). USDA Agriculture Handbook No. 703.