Citric Acid Promotes the Mobilization of Phosphorus under the Lower Concentration of Low Molecular Weight Organic Acids in Acidic Forest Soil

Table 1

The variations of P fractions induced by organic acids compared with other reports.

Soil type	Concentrations (mM)	Area	Organic acids	Soluble-Pi	Soluble -Po	NaHCO3-Pi	NaHCO3-Po	NaOH-Pi	NaOH-Po	HCl-P	Reference
Acid soil	100	Southwest China	Citric acid	↑	↑	↑	↑	↓	↓	↓	This study
			Oxalic acid	↑	↑	↑	↑	↑	↑	↓
			Malic acid	↑	↑	↑	↑	↓	↑	↓
Acid soil	10	Northeast China	Citric acid	ns	ns	—	↓	↓	—	—	[24]
			Oxalic acid	ns	ns	—	—	—	—	—
			Malic acid	ns	ns	—	—	—	—	—
Neutral soil			Citric acid	ns	ns	—	↓	—	—	—
			Oxalic acid	ns	ns	—	—	—	—	—
			Malic acid	ns	ns	—	—	—	—	—
Alkaline soil			Citric acid	ns	ns	—	—	—	—	—
			Oxalic acid	ns	ns	—	—	—	—	—
			Malic acid	ns	ns	—	—	—	—	—
Acid soil	10	Australia	Citric acid	—	↑	ns	ns	ns	ns	ns	[10]
			Oxalic acid	—	↑	ns	ns	ns	ns	ns
			Malic acid	—	—	ns	ns	ns	ns	ns
Alkaline soil	100	East China	Citric acid	↑	ns	↓	↓	↓	—	↓	[41]
			Oxalic acid	↑	ns	—	↑	↓	—	↓
			Malic acid	↑	ns	↓	↑	—	—	↓
Acid soil	1	South China	Citric acid	↑	↑	ns	ns	ns	ns	ns	[5]
			Oxalic acid	↑	↑	ns	ns	ns	ns	ns
			Malic acid	—	—	ns	ns	ns	ns	ns

Note: ns means no data; ↑ or ↓ means increase or decrease relative to control; - means no significant variation.