“…The boundary between low and medium nutrient classes of paddy soil are: < 1 g kg -1 of TN, 15 mg kg -1 of available P (Bray II) and 0.2 cmol kg -1 of exc. K (Nwilene et al, 2008). Accordingly, with the exception of the NV A2 and NV P clusters, the nutrient level of NV was classified as medium for N, low to medium for P and low to medium for K. Inthapanya et al (2005) reported that the use of K fertilizer for rice was much less than that of N or P, although the use of chemical fertilizer was altogether rare in Lao PDR.…”