Effect of sludge based compost on bhindi (Abelmoschus esculentus (L.) Moench) and amaranth (Amaranthus dubius Mart.) and soil fertility
Two field experiments were conducted to assess the effects of varying levels of substitution of organic manures with composted effluent sludge of gelatin industry on growth, yield, and nutrient uptake of bhindi (Abelmoschus esculentus (L.) Moench and amaranth (Amaranthus dubius Mart.). Sludge compost induced earliness in flowering and improved bhindi yield (p=0.01%) whereas the effect was not significant for amaranth. Lead (945 to 1085 mg kg–1), nickel (300 to 600 mg kg–1), and cadmium (22 to 48 mg kg–1) were detected in amaranth foliage regardless of the treatments, while these were absent in the bhindi pods. High soil sodium levels were detected in the bhindi plots receiving 75% manure through sludge compost although variations in soil pH, available phosphorous, potassium, calcium, magnesium, sulphur, iron, manganese, copper, zinc, boron, aluminium, nickel, cadmium, chromium, and lead levels were not pronounced. Soil analysis after amaranth, however, revealed significant differences between treatments for pH (5.48 to 6.56), available phosphorous (70 to164 mg kg–1), calcium (304 to 526 mg kg–1), manganese (range 59 to 118 mg kg–1), copper (4 to 10 mg kg–1) and zinc (4 to 13 mg kg–1). Mixed response of bhindi and amaranth indicate the need to undertake long-term trials based on continuous application of sludge-based compost before going for its commercial application.
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