Application rates - Soil analysis

Soil analysis for annual crops

• Soil testing has been widely introduced as a tool to determine the Mg availability in soils before planting.
  
  
• The available Mg pool (usually CaCl₂- extracts) is used together with soil texture and crop demand (uptake) as a basis for Mg fertilizer recommendation.
  
  
• Mg release from the mineral pool and losses by leaching are not accounted for and need to be estimated.

Soil fertility classes depending on soil type and exchangeable Mg contents in soils and deduced fertilizer recommendations for field crops.

Soil type	Clay content (%)	Fertility class
		A	B	C	D
		Mg content (mg kg-1)
Light soil (sand - loamy sand)	0 - 12	< 10	20-30	40-50	60-80
Medium soil (loamy sand - silty loam)	12 - 25	< 10	20-40	50-80	90-130
Heavy soil (clayey loam - clay)	> 25	< 20	30-60	70-120	130-200
Fertiliser recommendation = Crop removal (kg ha -1) x factor		1.5	1.2	1.0	0.5