Sulphur and Nitrogen Fertilization as a Potential Means of Agronomic Biofortification to Improve the Content and Uptake of Microelements in Spring Wheat Grain DM

Table 3

Chemical characteristics of the soil (before sowing).

Specification	Method of analysis	Unit of measure	Year 1 (2009)	2 (2010)	3 (2011)
pH (0.01 mol/L CaCl2)	Potentiometry with a methrohm-605 pH-meter	—	5.6	5.7	5.8
C-total	Combustion by LECO EC-12®	g/kg	9.2	8.9	7.7
N-total	By Kjeldahl’s method		0.9	0.9	0.7
N min	N-NO3 + N-NH4 × 1.38 (soil bulk density, mg/m^3) (PN-R-04038:1997)	kg/ha	72.8	68.4	64.9
P-available	Double lactate extraction and measurement by colorimetric assay by using the Egner Riehm DL method (PN-R-04023:1996)	mg/kg	54.5	53.5	48.3
K-available	Extraction: see above phosphorus and measurement by the photometric method (PN-R-04022:1996)		88.6	85.2	79.6
Mg-available	Extraction by 0.0125 m/L CaCl2 and measurement by AAS (PN-R-04020-1994)		34.8	33.7	35.1
S-total	By ICP-AES mineralization with HNO3 + Mg(NO3)2		102.8	86.3	72.0
S-SO4-available	Extraction with 0.025 m/L KCl and measurement by ion chromatography		14.2	12.6	10.3