Objects  Effects of NPK fertilizations on N-accumulation in organs of two Chamaecrista spp. were compared.

Method Five levels of N, P, and K fertilizer were applied in soil to determine the N contents in the stems, leaves, roots, and pods as well as the above- and under-ground parts of the Chamaecrista plants grown on the treatment soil to analyze their correlations.

Results The N contents in the organs of the plants under varied fertilization treatments ranked pods or leaves ＞ roots ＞ stems or aboveground parts ＞ underground parts. Appropriate amount of fertilizer significantly improved the N-accumulation in the organs as well as above- and under-ground parts. The greatest N-accumulation in the above- and underground parts of the two Chamaecrista spp. occurred when either 36 kg·hm⁻² N or 96 kg·hm⁻² P was applied, while that in the aboveground parts of C. rotundifolia by 60 kg·hm⁻² K application and of C. nictitans by 120 kg·hm⁻² K.

Conclusion Different fertilizations exerted a less significant effect than the plant species did on the N-accumulation of Chamaecrista spp.The Chamaecrista SPP treated with 36 kg·hm⁻² of nitogen and 96 kg·hm⁻² of phosphorus showed the highest nitrogen accumulation, while those receiving potassium in the range of 60 kg·hm⁻² to 120 kg·hm⁻² also exhibited maximum nitrogen accumulation. The N-accumulation positively correlated with the biomass and N contents in the stems and leaves, but negatively with the N content in the roots.