Soil Recommended Ranges for Washington Tree Fruit Production | WSU Tree Fruit

From: Bernardita Sallato, Extension Specialist, Agriculture and Natural Resources, Washington State University; Tianna DuPont, Extension Specialist, Agriculture and Natural Resources, Washington State University; David Granatstein, Sustainable Agriculture Specialist and Professor Emeritus, Washington State University. Revised December 2022. Download PDF EM119E

Table 1. Recommended soil test levels and testing methods for tree fruit. Source: Sallato et al.,2019

Soil test	Unit	Low	Optimal	Excessive	Method^a
pH	–	< 5.0	6.0 – 7.5	> 8.0	1:1 /CaCl
E.C paste	mmhos/cm	–	< 2.6	> 4	Paste
E.C 1:2.5 or 1:1	mmhos/cm	–	< 0.5	> 1	1:1
P-Olsen^b	ppm	< 10	15 – 40	> 50	NaHCO₃
Potassium (K)	ppm	< 120	150 – 250	> 300	NH₄OAc
Potassium (K)	meq/100g	< 0.3	0.4 – 0.6	> 0.7	NH₄OAc
Calcium (Ca)	meq/100g	< 3.0	4.1 – 20		NH₄OAc
Magnesium (Mg)	meq/100g	< 0.5	0.5 – 2.5	> 2.5	NH₄OAc
Sodium (Na)	meq/100g		< 0.5	> 0.5	NH₄OAc
Boron (B)	ppm	< 1.0	1.0 – 1.5	> 1.5	CaCl 0,01 mol/L
Sulfur (S)^c	ppm	< 4	9 – 20	> 20	Ca3(PO₄)2
Zinc (Zn)	ppm	< 0.25	0.6 – 1.0		DTPA
Copper (Cu)	ppm	< 0.1	0.6 – 1.0	> 20	DTPA
Manganese (Mn)	ppm		1 – 5	> 50	DTPA
Iron (Fe)^d	ppm	> 4.5	–	–	DTPA
	ppm		0.11 – 0.20	–	DTPA

Note: mg/kg = ppm. ppm = meq/100g*MW/charge*10.

^a Methods: Plant, Soil and Water Reference Methods for the Western Region. 2005. R. G. Gavlak, D. A. Horneck, and R. O. Miller.

^b P-Olsen is recommended to mildly acid to alkaline soils of eastern Washington. Gavlak et al 2005.

^c The method has a detection limit of 2.0 mg kg-1 (dry basis) and is generally reproducible to within ± 15%. Better to look at in tissue analysis.

^d Soil analyses for Fe, does not correlate well with Fe availability.