KALYANASUNDARAM, N. K.PRABHUDESAI, SHRIKANT S.2018-05-162018-05-162001http://krishikosh.egranth.ac.in/handle/1/5810046202The rapid growth of industries in states like Gujarat has also brought in the need for proper disposal/management of the industrial, effluent byproduct. The byproducts such as phospiiogypsum can sei-ve as a source of sulphur or calcium if heavy metal contaminants and toxic substances, if any, are kept low through pretreatments. Since 37 per cent of Gujarat soils are deficient in S, such S containing byproducts can meet the large requirement in the state. Looking in to the need to recycle such byproducts in a safe and effective way as soil amendments, the present investigation was undertaken to study three phosphogypsum byproducts of dye industry as axsource of S to crops. A field experiment was conducted on S deficient loamy sand soil (21 kg S ha-1) belonging to Typic ustochrept during kharif and rabi seasons of the years 1998-99 and 1999-2000. The fodder sorghum (var. GFSIH-1) during kharif and mustard (var. Varuna) in rabi seasons were grown as test crops. There were seventeen treatments (4 sources x 2 S levels x 2 periods alongwith one control) replicated three times in a randomized block design. Three phosphogypsum byproducts having concentration of heavy metals as Cd (ND), Cr (10-20 ppm), Ni (10 ppm) and Pb (10 ppm) alongwith the mineral gypsum containing Cd (ND), Cr (20 ppm), Ni (10 ppm) and Pb (10 ppm) were used as sources of sulphur in the experiment to supply 20 kg and 40 kg S ha-1. During the first year of experimentation the sulphur was applied to sixteen treatments for fodder sorghum crop. While, during second year, the fresh application of sulphur was done only in the eight treatments for fodder sorglium crop. The mustard crop was grown on residual effect of sulphur during both the years. Application of 40 kg S ha-1 gave significantly higher yield of both the crops than 20 kg S ha-1 and the control, the latter two treatments being at par in their effect irrespective of sources of S. The yield increase due to 40 kg S ha-1 was distinctly evident in the direct and cumulative effects of S treatments on the first and second sorghum crops and in their first residual effects on-the first and second mustard crops respectively. The second and the third residual effects of S treatments applied to the first crop of sorghum did not show any significant impact on the crop yield even at 40 kg S ha-1 level. There was no adverse effect on account of application of the three phosphogypsum byproducts on plant growth and yield of crops and yields were comparable with mineral gypsum treatments. The effect of treatments on the content and uptake of the nutrients such as N, P, K, Ca, Mg, S, Fe, Mn, Zn and Cu was studied. The S content of sorghum plant, mustard seed and mustard stover increased significantly over the control due to the direct and cumulative effects as well as their residual effects of application of 40 kg S ha-1 whereas the N content of sorghum plant increased due to the direct and cumulative effects of sulphur application at both the levels over control. In general, the application of 40 kg S ha-1 increased the metalic micronutrients content in the plant and it was conspicuous in (he direct and cumulative effects of S treatments and in their first residual effects. The three phosphogypsum byproducts did not increase micronutrient contents in plant more than that of mineral gypsum. The sulphur treatments significantly increased macro- and micronutrient uptake by plants as compared to the control in all the crops. The higher level of S application recorded significantly higher uptake of nutrients than the lower dose. All die sulphur sources were at par with each other in terms of nutrient uptake by crops In general, the Cr, Ni and Pb contents in the plants did not increase significantly due to,the different sulphur treatments in comparison to the control. The Cd was below the detectable limit. However, in accordance with the yield increase due to the S treatments, there was corresponding increase in the uptake of the heavy metals also. The Cr and Ni uptake by the first and second sorghum crops and in addition Pb uptake in the second sorghum crop were significantly increased due to the direct and cumulative effects of 40 kg S ha-1 respectively. The first residual effect of direct and cumulative effect of 40 kg S ha-1 treatments significantly increased Ni uptake in the first mustard crop and Pb uptake in the second mustard crop respectively. There were no significant differences in the uptake of heavy metals by plants due to the application of three phosphogypsum byproducts in comparison to mineral gypsum. No significant differences were observed in pH, EC, OC, available N, P, K and Mg content in soil after harvest of each crop due to different treatments. The Ca and S availability increased in the soil after harvest of first and second sorghum crops due to the direct and cumulative effect of 40 S ha-1 treatments irrespective of the source. Available metalic micronutrients did not vary in their contents in soil due to the 40 kg S ha-1 treatment except increase in Mn after the first sorghum crop, Fe after second sorghum crop,- Cu and Mn after the first mustard crop. Different sources of S were at par in their effect on the available micronutrient contents in soil. The direct and cumulative effects as well as their residual effects of the various treatments did not change the Cd, Cr, Ni and Pb availability in soil alter harvest of each crop. Thus the results of the present investigation indicated that the pretreated phosphogypsum byproducts containing low amounts of heavy metals can be safely used as a source of sulphur in S deficient soils for increasing crop yield.enAgricultural Chemistry and Soil ScienceA StudyThesis