Extraction of Soil Boron for Predicting Its Availability to Plants

Field and greenhouse studies were conducted in Prince Edward Island (P. E.I.) on soybean (Glycine max (L.) Merr.), red clover (Trifolium praten.se L.), alfalfa (Medieagn saliva L.), and rutabaga (Brassica napobrassica. Mill). Plant B concentrations were compared to soil B extracted by hot-water, 0.05 M HCI, 1.5 M CH3COOH and 0.01 M CaCl2. The r values for extractable soil B vs. plant B were: hot water (0.67). 0.05 M HCl (0.82), 1.5 M CH3COOH (0.78) and hot 0.01 M CaCl2(0.61). Results of soil B from the 0.05 M HCl extracts were generally found to give the best correlation and linear regression among the four extractants tested for predicting the availability of B to the plants. Overall, the 0.05 M HCl proved to be superior to hot water extraction and is recommended for predicting the available B status of the acid soils of P. E. I. The probability of error with 0.05 M HCL is less since it is shaken for a fixed period of time as opposed to subjective error which could be caused in monitoring the boiling t