Assessing sulphur deficiencies in soils and on-farm yield response to sulphur under rice (Oryza sativa)–wheat (Triticum aestivum) system in Garhwal region

Abstract

Sulphur (S) deficiency in rice (Oryza sativa L.)–wheat (Triticum aestivum (L.) emend. Fiori & Paol) growing areas of Garhwal region of Western Himalayan zone was delineated during 2003-2007. For this, 1191 soil samples (0-15 cm depth) were collected from Fakot and Chamba Agricultural Development Blocks (ADBs) of New Tehri Districts and analyzed for soil OC and available S content. Of the total, > 40% soils were low in OC content and occurrence of S deficiency was also associated with soil OC content. On S deficient soils of village Jajal (Fakot, ADB) and village Nagini (Chamba, ADB), on-farm experiments were conducted during 2004 to 2007 with four levels of S (0, 15, 30 and 45 kg S/ha) in a randomized block design under rice-wheat system. Rice yield increased (p<0.05) by 1.15 to 1.42 t/ha at Jajal and 1.14 to 1.55 t/ha at Nagini with 30 and 45 kg S application over no-S application in different years. Succeeding wheat yields also increased (0.66 to 1.27 t/ha and 0.41 to 1.16 t/ha, respectively) under residual S (30 or 45 kg S/ha) plots. Whereas, lower S application dose (15 kg/ha) did not leave residual effect on the succeeding wheat crop. Compared with (no-S), cumulative rice-wheat system S uptake at 30 and 45 kg S/ha was also higher by 102% to 134% at Jajal and 90% to 123% at Nagini. Skipping S application or under application of 15 kg S in fertilization schedule caused depletion in available S content of the soils by 1.0 to 2.7 mg/kg over initial S status at these study sites. After 03-crop cycles, apparent S balance was positive (10 to 57.3 kg/ha at Jajal and 14.7 to 67.0 kg/ha at Nagini) when rice received external fertilizer S input. On an average, value cost ratio (VCR) for rice-wheat system due to S fertilization ranged between 59 to 107 / invested in S at Jajal and 48 to 101/ invested in S at Nagini indicating the necessity of inclusion of S in fertilization schedule for sustained yield and profit of rice-wheat system in Garhwal region.