Data sources & terms

1The three workbooks

The agronomy in KiwiFert comes from three spreadsheets compiled in August 2026 from published New Zealand industry guidance. They ship with the application and are the only things that need editing when a figure changes; scripts/extract.py regenerates everything in data/ from them.

These describe typical New Zealand commercial practice. None of it is a recommendation. Fertiliser rates that are right for a block come from a soil test, a herbage or leaf test, a nutrient budget, and — where the block sits in a sensitive catchment — the regional plan. The Fertiliser Association of New Zealand Code of Practice for Nutrient Management is the governing document.

2Reference list

Governing documents

• Fertiliser Association of New Zealand, Code of Practice for Nutrient Management (with emphasis on fertiliser use), 2023 revision.
• Resource Management (National Environmental Standards for Freshwater) Regulations 2020, Subpart 4, sections 32–36 — the 190 kg N ha⁻¹ yr⁻¹ synthetic nitrogen cap and its reporting requirements. Ministry for the Environment, nitrogen cap guidance for dairy farms.
• Fertmark and Spreadmark quality assurance schemes — product analysis and agricultural lime particle size specifications.

Sector nutrient guidance

• Fertiliser Association of New Zealand, Lime Use on New Zealand Pastoral Farms (2019) — target pH by land use, lime rates, peat soil lime requirements, duration formulas, lime quality specifications.
• Fertiliser Association of New Zealand, A Guide to Fertiliser Use on New Zealand Dairy Farms (2024).
• Fertiliser Association of New Zealand, A Guide to Fertiliser Use on New Zealand Sheep and Beef Farms (2024).
• Fertiliser Association of New Zealand, Fertiliser Use on New Zealand Forage Crops (2020).
• Fertiliser Association of New Zealand, New Zealand soil Olsen P levels — approximately 1.58 million soil tests, 2012–2025. Source of the Olsen P target ranges by soil group.
• Reid JB & Morton JD, Nutrient Management for Vegetable Crops in New Zealand (Fertiliser Association of New Zealand).
• DairyNZ — Managing nitrogen fertiliser use; Soil fertility for pasture; Trace elements.
• Beef + Lamb New Zealand, Hill Country Futures: Phosphorus requirements (FS273); Hill Country Futures: Sulphur requirements; Fact Sheet 95, Trace element nutrition of sheep.
• FAR (Foundation for Arable Research), Arable Update 154 (nitrogen timing, dryland autumn wheat), 172 (yield and protein response to N and S in gristing wheat), 187 (yield response to nitrogen timing and rate in barley), 103 (the value of crop residues), 58 (nutrient content of maize grain residue); AIMI New Zealand survey of cereal and maize areas and volumes, 2024–2025; FAR Focus 6, Nutrient Management Plans.

Soils

• Hewitt AE (2010), New Zealand Soil Classification, 3rd edition, Landcare Research Science Series No. 1.
• Manaaki Whenua – Landcare Research, New Zealand Soils Portal and S-Map Online — soil chemical attributes, anion storage capacity, and the Fundamental Soil Layers.
• Landcare Research SINDI soil quality indicator tool — Olsen P interpretation by land use and soil group.
• Ballance Agri-Nutrients, phosphorus advice: availability in soil. Source of the 11 kg P ha⁻¹ per Olsen P unit for ash soils against 5 kg for sedimentary soils.
• Does soil anion storage capacity affect plant response to Olsen P status? New Zealand Journal of Crop and Horticultural Science (2020).

Products

• Ravensdown, published fertiliser product analyses, 2025–26.
• Ballance Agri-Nutrients, published fertiliser product analyses, 2025–26.
• Ministry for Primary Industries, purity of agricultural lime and dolomite used in New Zealand.

Crop and stock nutrition

• Grace ND & Knowles SO (2013), A recent assessment of the elemental composition of New Zealand pastures in relation to meeting the dietary requirements of grazing livestock, Journal of Animal Science 92:303–310. 1106 pasture samples; 76 % below the selenium requirement and 54 % below the cobalt requirement for sheep.
• Grace ND (2012), Trace element supplementation of livestock in New Zealand: meeting the challenges of free-range grazing systems, Veterinary Medicine International.
• New Zealand Avocado, nutrient removal with harvest.
• Seasonal uptake and partitioning of macro- and micronutrients in yellow-fleshed kiwifruit (Actinidia chinensis var. chinensis), Horticulturae 11(9):1003 (2025).
• Annual nutrient removal from irrigated vineyards in dry climates, American Journal of Enology and Viticulture 77(1).
• Yara New Zealand crop nutrition — maize and potato nutritional summaries.

Forestry

• Scion and the New Zealand Journal of Forestry Science: Will GM (1978), Nutrient deficiencies in Pinus radiata in New Zealand, 8(1); Mead DJ & Gadgil RL (1978), Fertiliser use in established radiata pine stands in New Zealand, 8(1); the national series of long-term intensive harvesting trials; NZ Forest Site Management Cooperative boron trials.
• New Zealand Forest Owners Association, fertiliser use in New Zealand planted forests.
• New Zealand Farm Forestry Association, boron deficiency in radiata pine.

Land use and production statistics

• Stats NZ, Agricultural production statistics: year to June 2024 (final); agricultural and horticultural land use indicators.
• Fresh Facts 2024 — New Zealand's Fresh Fruit & Vegetable Industry (United Fresh NZ with Plant & Food Research).
• New Zealand Winegrowers, Vineyard Report 2024.
• Millner JP, The New Zealand arable industry, in Ecosystem Services in New Zealand (Landcare Research).

General literature

• McLaren RG & Cameron KC, Soil Science: Sustainable Production and Environmental Protection.
• Reuter DJ & Robinson JB, Plant Analysis: An Interpretation Manual.
• Marschner H, Mineral Nutrition of Higher Plants.

General literature is used only where no New Zealand measurement exists, and every row resting on it is flagged Low confidence. Tissue nutrient concentration travels between regions better than yield does, so borrowed concentrations are usually within about 30 % — still wide enough to matter for an expensive input.

3Spatial data, via KiwiMap

Every site variable is read from KiwiMap, which holds the rasters and carries the full licence and attribution for each of them on its own Data sources & terms page. That page is authoritative; this is a summary of what KiwiFert actually reads.

The S-map licence is the restrictive one. Drainage, texture, depth and bypass flow are CC BY-NC-ND 4.0: non-commercial use only, and no distribution of modified versions. If you intend to use KiwiFert output commercially, either satisfy yourself that this is compatible with your use, or override those four fields by hand and disregard the mapped values.

There is no rainfall layer. KiwiMap carries wet days (≥1 mm) but not rainfall depth, so KiwiFert estimates annual rainfall from wet days and labels it as an estimate wherever it appears. It drives the sulphur leaching term and the lime longevity formula. Enter a measured figure from the nearest climate station if either matters.

4Confidence ratings

Every row of every workbook carries a confidence rating, and KiwiFert shows it wherever the row is displayed.

High

Anchored on a New Zealand measurement or an industry standard published by the Fertiliser Association, DairyNZ, Beef + Lamb New Zealand, FAR, Plant & Food Research or an equivalent body.

Medium

New Zealand data for the crop or soil group with interpolation to the specific case, or a well-replicated overseas dataset for something grown the same way here.

Low

Indicative. Derived from general literature and scaled to New Zealand practice. Treat as an order of magnitude and analyse the crop before committing fertiliser spend. Minor and emerging crops are mostly in this class.

5Disclaimer and limitations

KiwiFert output is for research, teaching and planning only. It is not a fertiliser recommendation, not a nutrient management plan, and not evidence of compliance with any regulation. No warranty is given as to accuracy, completeness or fitness for any purpose, and no liability is accepted for any decision taken on the basis of it.

Specific limitations, set out in full in section 12 of the method note:

• The workbooks describe typical practice, not requirement. Actual rates depend on soil and tissue test results this application does not have.
• Soil pH, carbon, cation exchange capacity and the climate variables are modelled national surfaces, not measurements at your block.
• Annual rainfall is estimated from wet days.
• The potassium, sulphur and nitrogen adjustment factors are KiwiFert's own interpretation of classes the workbooks state in words. They are editable and should be challenged.
• Tissue nutrient concentrations are central estimates; luxury uptake of potassium alone can double the tabulated value. Silicon, aluminium and chloride are the weakest columns.
• Rotations are the modal pattern for their sector, not a prescription.
• Nothing carries nitrogen over between rotation phases. The pasture-to-wheat and pulse-to-cereal credits are real and absent.
• There is no economics: no prices, no response functions, no optimisation. The economically optimal rate is almost always below the agronomically maximal one.

Three limits are treated as hard, and exceeding them is a regulatory or toxicological problem rather than a matter of judgement: the 190 kg N ha⁻¹ yr⁻¹ synthetic nitrogen cap on pastoral land, the 20 g Se ha⁻¹ selenium ceiling, and 3 kg B ha⁻¹ ahead of a cereal in the same rotation.

6Privacy

KiwiFert has no backend, no analytics, no cookies and makes no external network request. It runs entirely in your browser against files on your own machine.

The location you click, the values read there, your soil test results and your scenario are held in the page and in your browser's local storage, which is what lets a reload pick up where you left off. None of it is transmitted anywhere. Clearing the browser's site data, or pressing New, removes it.

A saved scenario file contains the coordinates of the block and any soil test results you entered. Treat it with whatever care those deserve before sending it to anyone.

The Show my location button on the map uses the browser's geolocation, which asks your permission and which browsers only allow on a secure origin (including localhost). The coordinates are used to centre the map and are not sent anywhere.

7Copyright and reuse

The KiwiFert application code, the method note and this page are © KiwiScience. The three source workbooks are compilations of published third-party guidance; the underlying figures belong to the organisations listed in section 2, and any substantial reuse of them should cite those sources rather than this application.

The spatial datasets keep their own licences, listed in section 3 and in full on KiwiMap's data sources page. You must comply with those licences — which for most of them means attribution, and for S-map means non-commercial use only and no distribution of modified versions — if you reuse the data further.

If you use KiwiFert in a thesis, a report or a paper, cite the underlying sources for the agronomy and describe the application as what it is: a calculator that applies published New Zealand practice to a mapped point, with the coefficients and assumptions set out in its method note.

Questions about the data, or a figure you think is wrong: start with How the calculations work, which names the sheet and the equation behind every number the application produces.

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