Table 1.

Average soil chemical parameters and soil history of onion fields surveyed in 2004 and 2005, by cultivation system and region in the Netherlands

Cultivation system	Region	Number of fields	Years under organic cultivationa	Onion yield (ton/ha)	Soil properties
					OMb	pH	Pwc	Cab	Kd
Organic		20	12.1	32	3.1	7.4	32	7.2	29
	Flevoland	15	13.8 (4–32)	33	3.1	7.4	32	6.5	30
	Zeeland	5	5.7 (1–12)	28	2.9	7.2	30	9.2	20
Conventional		19	–	70	3.0	7.3	44	5.1	26
	Flevoland	14	–	76	3.2	7.3	45	5.5	23
	Zeeland	5	–	59	2.5	7.5	42	2.8	33

^aAverage values. The range of values is indicated between brackets

^bOM organic matter (%), Ca CaCO₃ (%)

^cmg P₂O₅ l⁻¹ of dry soil. The difference in P content between cultivation systems was almost significant (REML analysis, p = 0.071)

^dmg K kg⁻¹ soil