Acceptable variability in soil testing report: A case study

Abstract

A study was conducted to find out the acceptable variation among the soil testing value of replicated samples collected from CRC field of SVPUAT, Meerut during 2013-14. Representative sample collected from 11 sub plots of CRC were divided into three replications and analyzed in the laboratory of Department of Soil Science. Soil testing values (STV) of different parameters like pH, EC, OC, available nitrogen , phosphorus and potash shows that at 0-15 cm soil depth maximum deviation of replicated sample from mean was 8.0% in pH , N,P and K while in case of EC and OC 23 and 17.6% , respectively. Similarly at 15-30 cm depth the deviation (8%) was same in case of pH, N, P and K but slightly higher ie. 26.6 and 18.3% was noticed in case of EC and OC, respectively. From the results it is clear that for pH, N, P, K, STV of all the soil sample deviated by <10% from mean whereas in case of EC 36% of soil samples deviated by <10% from mean and OC 91%, remaining 64% of EC and 9% of OC deviated between 11- 20%. As per results deviation of STV from mean the soil test report of CRC may be accepted because all the samples fall below 30% variation. From the results it can be further recommend that CV below 10% may be strongly accepted and between 10-20% may be moderately accepted and above 20% report may be rejected because majority of (96%) samples falls below 20 percent deviation. However, validation trial may be carried out at different location for confirmation of limits.