CONTENTS. 
Page. 
Introduction 7 
Availability of different phosphates applied to Hawaiian soils 8 
Soil types used 8 
Method 8 
Experiment 1 9 
Experiment II 15 
Experiment III ". 17 
Experiment IV 21 
Sand cultures 24 
Discussion 25 
Summary 29 
Solubility of different phosphates in Hawaiian soils 30 
Solubility of phosphoric acid in potted soil 30 
Solubility of phosphate fertilizer after addition to the soil 32 
Solubility of phosphate naturally occurring in Hawaiian soils 34 
Summary 40 
Acknowledgment 41 
Appendix 42 
The determination of phosphoric acid in Hawaiian soils 42 
(5) 
