Abstract– Extensive surveys were carried out covering as many as 40 orchards of Khasi mandarin in Thangal village of thesub-division Nungba under Tamenglong district in the year 2010-2011. Nutrientconstraints in the form of N, P, Ca, Mg, Cu, and Zn were identified using thesediagnostics which must find a due place in a fertilizer program of mandarinorchards of the region to obtain sustainable optimum fruit yield. The values ofavailable nutrients viz., N, P, and K across 40 orchards varied from 92.2 to348.2 mg/kg, 5.0 to 9.4 mg/kg, 110.0 to 440.1 mg/kg, respectively, withcorresponding coefficient of variation (%) of 11.8, 9.2, and 16.4 respectively.Soil micronutrients showed a large variation of 11.2- 48.1 mg/kg Fe (CV 16.2%),11.4-44.0 mg/kg Mn (CV 11.2%), 0.80-2.5 mg/kg Cu (CV 6.9%) and 0.50-2.8 mg/kgZn (CV 7.4%). Leaf nutrient concentration like soil fertility showed a widevariation from 1.62-2.62 % N, 0.04-0.12% P, 0.72-1.89% K, 0.90-2.24% Ca and0.28-0.61% Mg. Similarly, the micronutrients, namely Fe, Mn, Cu, and Znexpressed in ppm, varied from 118.4-282.3, 32.3-92.4, 1.0-3.8 and 14.6-28.4. Itwas observed that maximum nutrients are removed (in mg/tree) in the proportionof 171.90 N,17.19 P, 34.38K, 68.76 Ca, 17.19Mg, 0.34 Zn and 0.20Cu in relation to an average mean fruit yield of 34.38 (kg/tree) by Khasi mandarin i.e. orchard no. 1. Minimumnutrients are removed (in mg/tree) in the proportion of : 113.75 N, 11.37 P, 22.75 K, 45.50 Ca, 11.37 Mg, 0.22 Znand 0.13 Cu in relation to an average meanfruit yield of 22.75 (kg/tree) by Khasi mandarin i.e.orchard no. 9. These observations givean insight about the order in which, different nutrients are preferred byspecific citrus cultivar, and the ratio in which different nutrients areremoved. Such nutrient removal patterns are to be meted out in order tomaintain the sustained supply of the nutrients through soil.
Keywords– Khasimandarin, macro-micro nutrients, fertilizers, Tamenglong