Conversion Factors
Imperial to Metric units
| Imperial unit | Metric unit |
|---|---|
| 1 inch (in.) | 2.540 centimetres (cm) |
| 1 foot (ft) (= 12 in.) | 30.48 cm |
| 1 yard (yd) (= 3 ft) | 0.9144 metre (m) |
| 1 square yard (sq yd) | 0.8361 sq m |
| 1 acre (= 4840 sq yd) | 0.4047 hectare (ha) |
| 1 ounce (oz) | 28.35 grams (g) |
| 1 pound (lb) | 0.4536 kilogram (kg) |
| 1 hundredweight (cwt) (=112 lb) | 50.80 kg |
| 1 unit (1% of a cwt) (=1.12 lb) | 0.508 kg |
| 1 ton (= 2240 lb) | 1.016 metric tonnes (= 1016 kg) |
| 1 pint | 0.5682 litre (l) |
| 1 gallon (gal) (= 8 pints) | 4.546 litre |
| 1 fluid ounce = 1/20 pint | 0.02841 litre = 28.41 ml |
| 1 cubic foot | 28.32 litre |
| 1 bushel | 36.369 litre |
Conversion Factors:
| To convert | Multiply by |
|---|---|
| oz/acre to g/ha | 70.06 |
| Ib/acre to kg/ha | 1.121 |
| cwt/acre to kg/ha | 125.5 |
| cwt/acre to tonnes/ha | 0.1255 |
| unit/acre to kg/ha | 1.255 |
| tons/acre to kg/ha | 2511 |
| tons/acre to tonnes/ha | 2.511 |
| gal/acre to litre/ha | 11.23 |
Meteorological data:
| To convert | Multiply by |
|---|---|
| Temperature: | |
| °F to °C | subtract 32 and multiply by 0.5556 |
| °C to °F | multiply by 1.8 and add 32 |
| Solar radiation (RAD): | |
| J/cm2 to MJ/m2 | 0.01 |
| MJ/m2 to W/m2 | 11.6 |
| Wind measurements: | |
| Knots to m/s | 0.5144 |
| From 10m to 2m height (see equation (1) below) | 0.78 |
| From 2m to 10m height (see equation (1) below) | 1.28 |
| Average daily windspeed (m/s) from total daily windrun (km in 24 hours) | 0.011574 |
| Total daily windrun (km in 24 hours) from average daily windspeed (m/s) | 86.4 |
| Beaufort wind scale number (B) to windspeed (m/s) at 10m | 0.836 B3/2 |
| Vapour pressure (VAP): | |
| kPa to mb | 10 |
Equations for wind measurements:
- 1) Adjusting wind measurements for different heights of
measurement:
Vh/V10 = 0.233+0.656*log10 (h+4.75)
where Vh = speed in knots at height h, V10 = speed at 10m and h = height in m (Met Office 1982). - 2) Converting the Beaufort scale wind speed:
v = 0.836 B3/2 m/s
Where v is the equivalent wind speed at 10 metres above the sea surface and B is Beaufort scale number.
Chemical components of fertilizers:
| Oxide to element | Multiply by |
|---|---|
| P2O5 to P | 0.436 |
| K2O to K | 0.830 |
| MgO to Mg | 0.603 |
| SO3 to S | 0.400 |
| CaCO3 to Ca | 0.400 |
Epsom salts: A crystalline form of magnesium sulphate, MgSO4.7H2O.
Kieserite: A crystalline form of magnesium sulphate, MgSO4.H2O.
References:
- Rothamsted (1974), "Conversion Factors", Yields of the Field Experiments, 1973, pp 406-407 DOI: 10.23637/ERADOC-1-98 (whole book).
- Meteorological Office (1982) "Observer's Handbook, 4th Edition, Met.0.933
- Meteorological data: Instrument Description
- DEFRA (2010) "Fertilizer Manual (RB209)" 8th Edition. The Stationery Office, UK. https://ahdb.org.uk/rb209
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