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Sewage effluent is the carrier of huge amounts of N (0.09 to 0.16%), P (0.023 to 0.029 %), and K (0.11 to 0.18%) and as well as it is rich in organic carbon (3.27%). Transfer of the toxic trace metal (Pb) from the contaminated site can be seized out from the food chain through application of FeSO4.7H2O and CaSO4 in a larger area. The efficacy of the toxic metal immobilization through an application of FeSO4.7H2O and CaSO4 was studied in the laboratory and tested in the field. In batch experiments, application of FeSO4 at the rate of 5% (on soil weight basis) indicated a greater decrease in soil pH (from 7.54 to 5.55) in half an hour of shaking period as a result of which water soluble and exchangeable Pb concentrations decreased by 100%. Application of CaSO4 also decreases soil pH, as well as Pb concentration in soil solution. Pot culture experiments with two flower and leafy vegetable plants also show decrease in bioavailability of Pb in FeSO4 treated soils.

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Sustainable improvements in agricultural production and productivity necessitate efficient resource utilization and relay intercropping to improve crop yield and land productivity while using fewer inputs. Thus, in a 3-year field trial, different cucurbit vegetable crops were tested to see if they were suitable for relay intercropping with castor (Ricinus communis L.). These treatments encompassed various intercropping strategies involving castor, each paired with a different cucurbits such as bitter gourd (Momordica charantia), ridge gourd (Luffa acutangula), snake gourd (Trichsanthus cucumerina), bottle gourd (Legenaria siceraria), coccinia (Trichsanthus dioica), and cucumber (Cucumis sativus). The results showed that the castor and cucumber relay intercropping systems produced the highest castor equivalent yield (1,701 kg ha^-1), followed by castor and ridge gourd (1,596 kg ha^-1). Among all the cucurbit intercropping systems, the castor+cucumber relay system had the highest productivity (4.66 kg ha^-1 d^-1), profitability (4.07 $ ha^-1 d^-1), and relative economic efficiency (198.5%). The best moisture-use efficiency was achieved by castor and bitter gourd relay intercropping (6.58 kg/ha/mm), followed by castor and bottle gourd relay intercropping (6.35 kg ha^-1 mm^-1). There was a higher net return for relay intercropping of castor and cucumber ($ 1,483.9 ha^-1), followed by castor and ridge gourd ($ 1,446.2 ha^-1). Sole castor produced 1312 kg ha^-1, despite its low monetary returns of $ 501.6 ha^-1. It has been found that relay intercropping between castor and ridge gourd (3.29), followed by castor and bitter gourd (3.29), produces the highest benefit-cost ratio. As a result, the relay intercropping system, which determines the competitive interaction and productivity of castor and cucurbits, can provide the greatest benefits.