a https://catalog.data.gov/dataset/major‐land‐resource‐areas‐mlra.
Soil Characterization
Soil characterization includes providing a taxonomic description of the typical or most common soil(s) within the experimental site. Inclusion of the taxonomic system is needed for international comparisons. Soil type (e.g., Barnes clay loam), soil texture (sand, silt, and clay contents), typical pH, and bulk density are common soil characteristics, preferably by depth increments. Soil chemistry data include soil C (total, organic, and/or inorganic), soil N (total, NO3, and NH4), and other plant‐essential nutrients (e.g., P and K). Topographic information can be at a broad‐scale site level but can also have much finer granularity related to sampling for response variables. When appropriate, the hillslope position should be noted.
Experimental Descriptors
Experimental descriptors include experimental design (e.g., randomized complete block, split plot), number of replications or plots, study area, plot size, and treatments.
Climate and Weather
Climatic data include long‐term information such as mean annual temperature and mean annual precipitation. It is also useful to include climate characterization descriptors (Kottek, Grieser, Beck, Rudolf, & Rubel, 2006). Finer granularity of climatic data can also be useful, noting if the region experiences freeze–thaw cycles. Weather data might be as simple as noting the location of the nearest weather recording station, while including a link can be especially useful to the modeling community.
Management
Management includes soil, crop, and residue management, cropping related amendments, harvest, and animal management. Within the context of an experiment, management parameters might be considered metadata or treatment data. For example, if the entire study area is managed with a common tillage method or the same cultivar, it would be management metadata. In contrast, if tillage systematically varies across a study based on the selected experimental design, the management is an experimental treatment.
Tillage
When describing tillage, vague terminology like conventional or conservation should be avoided or if used, these terms need to be clearly described by delineating the implement, mode of soil movement (e.g., inversion tillage), depth, tillage frequency, and the date tillage event(s) occur.
Cropping System
Cropping systems include listing the crop species with Latin binomial, cultivar, crop rotation, and cropping history. Enough information needs to be provided to understand key parameters if the system is defined as “conventional” or “organic.” Clearly indicate if an organic system adheres to the USDA organic standard (https://www.ams.usda.gov/sites/default/files/media/Organic%20Production‐Handling%20Standards.pdf) or another organic certification standard when appropriate because it denotes that specific practices have been followed. When cover crops are included in the system, the corresponding information should be included as noted for crop management.
Amendments
Amendment within this context is used to denote fertilizers, pesticides, or any organic (e.g., animal manure, biochar) or synthetic material applied. The information recommended includes the formulation, active ingredients when applicable, rate, application method, and date applied. For manure, the animal source and nutrient content (C, N, P, etc.) is recommended.
Crop Management
Crop management includes information about planting rate, row spacing, and when and how cover crops were planted. Likewise, how was the crop was harvested, what was harvested (just grain or a portion of the residue), including other residue management practices (e.g., harvest or burning) should be included. The mass of biomass retained in the field is an important aspect of soil health research because it is the raw material for building nascent soil organic matter, driving nutrient cycling. In those studies that include cover crops, detailed metadata are recommended (species; cultivar; planting date, rate, depth, and method; biomass; termination method and date).
Livestock Management
Livestock management needs to include animal species, animal class, stocking rate, duration of grazing, and frequency for rotational grazing. Information related to manure applications should be included under agricultural amendments. Manure management may not directly apply to soil health, but if a greenhouse gas mitigation or lifecycle analysis assessment is being conducted, the information would be desirable.
Sample Collection, Preparation, Storage, and Analysis
Sampling requires its own metadata describing the what, when, where, and how of sample collection. It is the information typically included in the materials and methods section of a paper. What describes the sampled material (e.g., soil, plant, air). The resolution of when is sample dependent; for example, yield may need only a date or simply a year. Biomass sampling should include a crop‐appropriate growth stage description and biomass properties (C, N, or
