BFDC Database
Soil test-crop response (N, P, K and S fertiliser) trials have been undertaken by many different organisations since the late 1950's. As new soil tests were developed in Australia, soil test criteria (defining soil test values at near optimum or maximum yield for a specific crop) were developed for interpreting the nutrient status of cropping soils for growers.
Trial results have been recorded in scientific publications, project reports, extension publications (e.g. regional trial report books) or field and office archives. Commonly, experimental designs varied from trial to trial and hence different amounts of data were collected and reported.
All of the relevant soil test-crop response data that could be obtained for each trial have been entered into the BFDC database.
Contents
- Trial data requirements
- Grain crops included in BFDC
- Soil tests included in BFDC
- Converting soil test units
- Australian Soil Classification
Trial data requirements
For inclusion in the BFDC database, soil test response trials had to supply essential details including:
- Site location.
- Crop type.
- Experimental design.
- Soil sampling depth.
- Soil test method and the units reported.
- Mean grain yield (t/ha) for each treatment.
- Data owner and custodian.
- Y0, Ymax and the equation fitted treatment yields.
Additional descriptive trial data (metadata) were also added where available. Examples of metadata included in the database were:
- Australian Soil Classification, soil texture and soil attributes (e.g. organic carbon and pH).
- Farming system including land use history.
- Year and type of trial.
- Crop variety.
- Fallow and stubble management.
- Tillage system.
- Sowing date, row spacing and sowing depth.
- Harvest details.
- Environmental characteristics (e.g. growing season rainfall).
- Observations of trial crop constraints (e.g. frost or toxicity).
- Any publication details.
Trials that were not added to the database were those that included:
- Un-replicated treatments (except for yield surface designs with a large number of rates of a single nutrient).
- Linear yield response (whereby Ymax can not be defined).
- Trials where several fertiliser products were compared at 1 or 2 levels of nutrient application (e.g. ± a nutrient rate).
- Crop growth or yield were known to have been affected by disease, frost, drought, other nutritional constraints, soil toxicities (e.g. acidity, salinity, sodicity or B toxicity) or storm damage.
Some trials were included in the database where:
- Trials included fertilisers containing more than 1 plant nutrient (e.g. either single superphosphate or sulphate of ammonia) and the crop response could have been partially attributed to say S and not P or N (especially if no S soil test data were collected).
- A replicated optimal level of an applied nutrient was compared to an unfertilised control treatment (e.g. ±S on wheat or canola).
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Grain crops included in BFDC
BFDC included all available soil test-crop response trials for crops grown from the sub-tropical regions in northern Australia, through the temperate regions of south eastern Australia, and into the Mediterranean regions of southern Australia. Across these regions, a diverse range of crops have been grown, on a range of soil types using a variety of farming systems and practices.
The BFDC team searched for the following soil test-crop response trials:
| Cereal crops | Pulse crops | Oilseed crops |
|---|---|---|
| Wheat (types and varieties) | Lupin (narrow leaf, albus and yellow types and varieties) | Canola (and rape seed) |
| Barley (malting and feed varieties) | Faba Bean | Mustard |
| Sorghum (grain and fodder varieties) | Field Pea | Sunflower |
| Oats (grain and fodder varieties) | Chickpea | Peanut |
| Cereal rye | Lablab | Soybean |
| Maize (grain and fodder varieties) | Lentil | Safflower |
| Triticale | Mung Beans | Sesame |
| Millet | Narbon Bean | Linola |
| Navy Bean | Linseed/Flax | |
| Pigeon Pea | ||
| Vetch | ||
The BFDC team did not examine:
- Sugar cane, rice or cotton trials or trials that did not include grain yields (e.g. Oat trials assessing fodder response to fertiliser nutrient only).
- Soil test-crop response trials for pastures. These are included in the Making Better Fertiliser Decisions for Grazed Pastures in Australia database.
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Soil tests included in BFDC
Many different soil testing methods have been used for N, P, K and S fertiliser rate trials in Australia. Important soil testing methods included in the database are:
| Nitrogen | Phosphorus | Potassium | Sulphur |
|---|---|---|---|
| Nitrate N | Colwell P | Colwell K | KCl 40 extractable S |
| Ammonium N | DGT extractable P | Exchangeable K | CPC S |
| Nitrate N+Ammonium N | Mehlich 3 P | MCP S | |
| Total soil N | BSES P | ||
| Olsen P | |||
| Phosphorus Buffering Index | |||
The available soil test results for other analytical methods are included in the database where these were available.
Different soil test results were reported using a range of units (e.g. mg/kg, kg/ha and in cmol(+)/kg). The reported units have been included in the database. In some cases, where sufficient scientifically valid information has been available, data have been converted so that a larger body of data is available for a given unit of description (e.g. nitrate N kg/ha into nitrate N mg/kg).
Choice of soil sampling depth varied from trial to trial. The BFDC team recommend that:
- Nitrogen should be sampled at 0-60 cm or using a series of depths that can be aggregated to 60 cm. Soil test results should be reported as nitrate-N mg/kg and kg/ha.
- Phosphorus should be sampled at 0-10 cm and reported in mg/kg.
- Potassium should be sampled at 0-10 cm (also consider 0-60 cm).
- Sulphur should be sampled at 0-60 cm (but also consider 0-10cm).
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Converting soil test units
Commonly used conversions between older and modern units for soil tests and irrigation water salinity are:
| Older units | Historic units | Conversion multiplier | Current units |
|---|---|---|---|
| Exchangeable cations | meq/100 g | x1 | cmol(+)/kg |
| Concentration | ppm or mg/g | x1 | mg/kg |
| Soil Salinity (Electrical Conductivity) | µS/cm | x0.001 | dS/m |
| Irrigation Water Salinity (total soluble salts) | mg/L | ÷670 | (EC) dS/m |
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Australian Soil Classification
Approximate relationships between the Australian Soil Classification, Great Soil Groups and the Northcote factual Key are as follows:
| Australian Soil Classification (ASC) | Great Soil Groups | Northcote Factual Key |
|---|---|---|
| Calcarosols: soils that are usually calcareous throughout the soil profile (often highly calcareous). | Solonised brown soils, grey-brown and red calcareous soils, mallee soils, highly calcareous sands, lithosols, rendzina | Gc1, Gc2, Um1, Um5 soils |
| Chromosols: soils with a strong texture contrast between the topsoil and subsoil. Subsoils are not strongly acid and are not sodic. | Non-calcic brown soils, some red-brown earths, red and brown podzolic soils, red and brown duplex soils | Many forms of duplex (D) soils |
| Dermosols: soils with structured subsoils that lack a strong textural contrast between the topsoil and subsoil. | Red gradational soils, prairie soils, chocolate soils, some brown, red and yellow podsolic soils, kraznozem, rendzina, chenozem, terra rossa | Wide range of Gn3 soils, some Um4 soils |
| Ferrosols: soils that have subsoils that contains a high content of free iron oxide and which lack a strong texture contrast between the topsoil and subsoil. | Krasnozem, euchrozem, chocolate soils | Gn3, Gn4, Uf5, Uf6 soils |
| Kandosols: soils that lack a strong texture contrast between the topsoil and subsoil, having at best a weakly-structured subsoil and not calcareous throughout. | Red, yellow and grey earths, calcareous red earths, earthy sands, brown podsolic soils or lithosols | Gn2, Um5 soils |
| Kurosols: soils with a strong texture contrast between the topsoil and strongly acid subsoil. These soils can have high levels of magnesium, sodium and aluminium in the subsoil. | Many podsolic soils and soloths | Many strongly acid duplex soils |
| Organosols: soils dominated by organic material. | Neutral to alkaline, and acid peats | Organic soils |
| Podosols: soils with a subsoil dominated by the accumulation of compounds of organic matter, aluminium and/or iron. | Podsols, humus podsols, and peaty podsols, lateritic podsols | Many Uc2, some Uc3, Uc4 soils |
| Rudosols: includes soils with little pedological organisation. These soils are usually 'young' in the sense that soil forming factors have little time to pedologically modify parent rocks or sediments. The component soils can vary widely in texture and depth; many are stratified and some are highly saline. | Lithosols, alluvial soils, calcareous and siliceous sands, some solonchaks, deep gravelly soils | Uc1, Um1, Uf1 soils |
| Sodosols: soils with strong texture contrast between topsoil and subsoil horizons. These soils are not strongly acid but are sodic and have an ESP greater than 6. | Solodized solenetz and solodic soils, some soloths and red-brown earths | Many duplex soils |
| Tenosols: soils with generally weak pedological organisation in the subsoil. | Lithosols (shallow stony soil), siliceous and earthy sands, alpine humus soils and some alluvial soils, some terra rossa, brown earths | Many Uc and Um classes |
| Vertosols: clay soils with shrink-swell properties that exhibit strong cracking when dry. Some of these soils also show gilgai microrelief. | Black earths, black, grey, brown and red (cracking) clays | Ug5 soils |
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