A comparative study of MAF (Ruakura) and DSIR Land Resources soil analysis results

Abstract New Zealand topsoil samples from 108 soils were analysed for pH, phosphate retention, exchangeable cations (calcium (Ca), magnesium (Mg), potassium (K), and phosphate-extractable sulphur (S) at MAF Technology, Ruakura Agricultural Centre, Hamilton, New Zealand and DSIR Land Resources (DLR), Lower Hutt, New Zealand and results compared. Ruakura determinations followed their standard soil test procedures for fertiliser advice, which meant that extraction times were significantly less than those ofDLR for the determination of phosphate-extractable S and particularly for the cations Ca, Mg, and K. There were other specific method differences also. However, the methods used by both laboratories for pH and phosphate retention were closely comparable. Linear regressions (significant at 0.1%) best described the relationships between Ruakura and DLR values, for all determinations except phosphate-extractable S where an exponential curve (also significant at 0.1%) best described the relationship. The poore...