Critical Limits of Zinc in Soil and Rice Plant in Valley Soils of Manipur
Department of Soil Science & Agricultural Chemistry, College of Agriculture, Central Agricultural University, Imphal 795004, Manipur (India), India
ABSTRACT
A pot study was conducted to estimate the critical limit of zinc (Zn) in soil and rice plant in rice growing soils of Manipur. Thirtysix soil samples were collected from different paddy fields of four valley districts namely Imphal-east, Imphal-west, Thoubal and Bishnupur district of Manipur using Stratified Random Sampling. All the soil samples were acidic in reaction ranging frompH 4.9 to 6 with mean value of 5.32, organic carbon content 0.79 to 3.51 %, cation exchange capacity of the soils 8.3 to 24[cmol (p+ ) kg-1 ] and the clay content of soil varied from 20 to 73.2 % (mean 50.46%). The DTPAextractable Zn showed a positive correlation with dry matter yield (r=0.939**), Bray’s per cent yield (0.901**), Zn content (0. 977**) and Zn uptake (0.984**). The critical limit of Zn in these soils was established at 0.78 mg kg-1 for rice and critical limit of 75 days old rice plants is 24.5 mg kg-1 , below which response to Zn fertilization may be expected. Soil containing Zn below this critical limit may be responded economically to Zn fertilization for rice growing.
