Abdul Fatah Soomro TITLE: For Doctor of Philosophy in (Agriculture) Major Agronomy INTEGRATED EFFECT OF INORGANIC AND ORGANIC FERTILIZERS ON THE YIELD SUSTAINABILITY OF PLANT AND RATOON SUGARCANE (Saccharum officinarum L) Integrated nutrient management is an important tool in crop production. Inadequate or excessive fertilizer applications not only limit crop yield but deteriorate soil and environment. This study was conducted to determine the optimum inorganic and organic nutrient sources and rates for sugarcane production. In this regard, field experiments were conducted at Sugarcane Section, Agriculture Research Institute, Tandojam, Pakistan, located at 25 o 25’60’N 68 o 31’ 60E during 2008-09 and 2009-10. In all the experiments, Thatta-10 sugarcane variety was sown. The experiment-1, was meant to observe the effect of inorganic NPK fertilizers under different proportions on growth, yield and juice quality of sugarcane; comprised different inorganic NPK fertilizer doses viz. Control (0-0-0 NPK kg ha -1 ), 100% recommended (225-112-168 NPK kg ha -1 ), 75% less than recommended (56.25-28.0-42.0 NPK kg ha -1 ), 50% less than recommended (112.5-56.0-84.0 NPK kg ha -1 ), 25% less than recommended (168.75-84.0-126.0 NPK kg ha -1 ) and 25% more than recommended (281.25-140.0- 210.0 NPK kg ha -1 ). In this study agronomic, physiological, quality and nutrient uptake traits viz. tillers plant -1 , plant height, stem girth, internodes plant -1 , internode length, millable canes, cane yield, leaf area plant -1 , leaf area index, crop growth rate, dry matter, brix, pol, purity, commercial cane sugar, NPK accumulation and uptake in plant and ratoon sugarcane crops were higher with the application of 100% recommended fertilizer at 225-112-168 NPK kg ha -1 ,and 25% more than recommended fertilizer at 281.25-140-210 NPK kg ha -1 . The mean values of these both NPK levels were statistically non-significant. However, all inadequate applications beyond recommended applications significantly recorded less values of all traits of sugarcane plant and ratoon crop. The second experiment on integrated use of inorganic and organic nutrients in sugarcane for obtaining maximum cane and sugar yield, consisted organic and inorganic nutrient sources and levels viz. control (0-0-0 NPK kg ha -1 ), 100% recommended (225-112-168 NPK kg ha -1 ), FYM and PM 10 & 20 t ha -1 , BF 5 & 10 t ha -1 sole and each organic sources were used in combination with 25% & 50 % less than recommended inorganic fertilizers. The results showed that inadequate rates or individual application of inorganic or organic nutrient sources recorded less values of all sugarcane traits. The maximum tillers plant -1 , plant height, stem girth, internodes plant -1 , internode length, millable canes, cane yield, leaf area plant -1 , leaf area index, crop growth rate and dry matter in plant crop were found with the application of FYM and or press mud applied at 20 t ha -1 with 25% less NPK fertilizer than recommended dose of 168.75-84.0-126.0 NPK kg ha -1 . Both the treatments were statistically non-significant. However, quality and nutrient uptake traits viz. brix, pol, purity, commercial cane sugar, NPK accumulation and uptake in sugarcane plant crop were higher with the application of 25% less fertilizer than the recommended (168.75-84.0-126.0 NPK kg ha -1 ) + 20 tons press mud ha -1 . The study on effect of inorganic NPK and residual organic nutrient sources on subsequent sugarcane ratoon crop showed maximum tillers plant -1 , plant height, xstem girth, internodes plant -1 , internode length, millable canes, cane yield, leaf area plant -1 , leaf area index, crop growth rate, dry matter, brix, pol, purity, commercial cane sugar, NPK accumulation and uptake under residual impact of press mud and or FYM at 20 t ha -1 + supplemental application of 25% less inorganic NPK fertilizer (168.75-84.0-126.0 kg ha -1 ). It is concluded that inorganic fertilizers increased growth, yield, and nutrient uptake of sugarcane plant and ratoon crop. Integrated nutrient management recorded 25% saving in inorganic NPK fertilizers due to application of FYM and or press mud applied at 20 t ha -1 . The residual effect of FYM and press mud showed significant effect on subsequent ratoon crop. The residual FYM and or press mud at 20 t ha -1 + supplemental application of 25% less inorganic NPK fertilizer (168.75-84.0-126.0 kg ha -1 ) was found sufficient nutrient level. The applications of FYM, press mud and biofertilizers without inorganic NPK fertilizers were found less efficient. This study recommends that organic and inorganic nutrients should be applied to enhance growth, yield, quality and nutrient uptake of both plant and ratoon sugarcane. Residual effects were seen on the subsequent ratoon crop due to FYM and press mud applications. Therefore, application of FYM and or press mud at 20 t ha -1 once in a two year with 25% less NPK fertilizer at 168.75-84.0-126.0 kg ha -1 is recommended for achieving higher cane yield.