Vol. 12, Issue 7 (2023)

Author(s):
Dharmendranaik E, Durga Devi KM, Beena VI and Geetha P

Abstract:
An experiment was conducted at Kerala Agricultural University, College of Agriculture, Vellanikkara in 2019 to investigate the effects of nutrient management practices on the levels of nitrate and oxalate in cooked and raw amaranth. The study employed a factorial completely randomized design with five nutrient management treatments and two types of soils (black soil and lateritic soil). The results indicated significant variation in the levels of nitrate and oxalate, which are anti-nutrients, in both cooked and raw amaranth. Cooking was found to reduce the content of nitrate (33.83 to 2.27%) and oxalate (20.13 to 11.20%). The nitrate and oxalate contents in cooked amaranth ranged from 498.66 to 2126.66 mg/kg and 2130.94 to 3361.49 mg/kg, respectively, while in raw amaranth, the nitrate and oxalate contents ranged from 1056.00 to 2229.33 mg/kg and 2641.17 to 4055.12 mg/kg, respectively. Among the soil types, lateritic soil (Alfisol) registered significantly lower levels of nitrate and oxalates in cooked as well as raw amaranth. Among the treatments, T₁ (organic KAU-POP+FYM 25t/ha) had recorded significantly lower amounts of nitrate. In the case of raw samples it was on par with T₅- (soil test-based application of nutrients with FYM 25 t/ha). In the case of oxalate, cooked samples of T₁ registered significantly lower value which was also on par with T₅. Oxalate content in raw samples of T₁ was also significantly lower than the other treatments. The data obtained from the experiment also indicated significant variations in amaranth yield across different soil types and nutrient management practices as well as their interaction. Among the treatments, the one receiving T₄ (NPK-100:50:50 in the form of Factamphos and MOP, along with FYM-25t/ha) showed a significantly higher yield in both soil types. The yield from this treatment was similar to that of T₂ (KAU-POP NPK-100:50:50 with urea, SSP, MOP + FYM- 25t/ha) and T₃ (NPK-100:75:75 with urea, SSP, MOP + FYM-25t/ha + lime based on soil test). The lowest yield was observed in T₁ (organic KAU-POP) and soil test-based application of nutrients with FYM-25t/ha (T₅) exhibited comparable yield to that of T₂ and T₃. The results indicated clearly that the application of organic manure alone is a good practice to reduce the nitrate and oxalate content in amaranth. However, yield is a limiting factor for organic POP treatment. Among the integrated nutrient management practices, soil test-based application of nutrients + FYM-25 t/ha showed superiority over the other treatments in reducing the contents of anti-nutrients in amaranth along with reasonably good yield.