Sample Volume Effect on the Determination of Nitrate-Nitrogen in the Soil Profile
A field experiment was conducted to evaluate the effect and reliability of soil sample volume on nitrate-nitrogen (NO3-N) and soil-water content in the soil. Four soil sampling devices (a 20.3-cm power earth auger, a 5.1-cm hand earth auger, a 3.2-cm soil probe and a 1.9-cm soil probe) were used to collect soil samples from 35 conventionally tilled and 35 no-till locations. Soil samples were taken at 30-cm intervals to a depth of 150 cm with each of the four sampling devices and were analyzed for NO3-N and moisture contents. Results of this study indicate that sample volume has no significant effect on determining soil-moisture content. Sample volume also had no effect on NO3-N concentration in the soil water under no-till conditions but had a definite impact on the NO3-N levels in the conventionally tilled soils. Results further indicate that a 5.1-cm diameter sample may best predict the quantity of residual soil NO3-N.
This article was published in Transactions of the ASAE 32 (1989): 934–938, doi:10.13031/2013.31094. Posted with permission.