Long-term Farming System Comparison Trial in India

Background: Developing sustainable farming system on large scale is very important for sustainable development of global agriculture. Scientific information about organic vs. conventional agriculture in the tropics is sparse

Kinetics of oxidation of pyridoxine by manganese (Ill) in pyrophosphate Inedium

42-46Manganese(III)has been stabilised in weakly acidic solution by means of pyrophosphate and the nature of the complex formed elucidated spectrophotometrically. Stoichiometry of manganese(III) oxidation of pyridoxine hydrochloride (PRX) in pyrophosphate medium has been established in the pH range below 1 to 5 by iodometric, gravimetric and spectrophotometic methods. Kinetics of the reaction has bee studied over the pH range 2.5 to 3.5. The oxidation follows second order kinetics with Mn(III), as evide nt from the linearity of 1/[Mn(llI)] versus time plot. The effect of varying [Mn(llI)], [PRX],added [MnIl)), dissociated [H+], total [P2O] and added ClO, Cl- and SO ions have also been studied. The order in [PRX] is unity and increase in lH+] increases the rate. With increase in [Mn(Il)] and [P2O] a retardation effect is noticed. Oxidation products have been identified. De:pendence of reaction rate in temperature has been studied, actication parameters computed from : the Arrhenius and Eyring plot. A mechanism consistant with kinetic results has been proposed

Potentiometric studies on electrolytically generated manganese(III) acetate in aqueous acetic acid: Oxidation of thiosemicarbazide, its metal complexes and thiosemicarbazones

49-53Conditions for generating manganese (lll) acetate electrochemically with high current efficiency have been determined in aqueous acetic acid solutions. Nature of the manganese species formed has been elucidated spectro-photometrically. Conditions for potentiometric determination of thiosemicarbazide (TSC), its metal complexes and thiosemicarbazones have been investigated. Thiosemicarbazide has been found to undergo four electron oxidation whereas its metal complexes M(TSC)2SO4' participate in eight electron redox process, indicative of the number of TSC-ligands present in the complexes. All the thiosemicarbazones with the exception of salicylaldehyde thiosemicarbazone, undergo four electron redox process with the regeneration of the respective aldehydes. Salicylaldehyde thiosemicarbazone reacts in two stages namely four electron oxidation of thiosemicarbazone with the regeneration of salicylaldehyde which is further oxidised at elevated temperature to salicylicacid. The formal redox potentials of Mn(lll)-Mn(II)couple at various percentages (v/v) of acetic acid and.in the presence of anions CH3COO-, Cl-, F-, ClO4 have been determined and compared with the earlier work involving manganic sulphate in H2SO4-HOAc medium. The reactive species envisaged in the present system are the undecomposed manganese(lll) acetate or the complex, Mn(OAc),while the earlier system contains free aquo manganic ions, Mn3+ aq. or MnOH2+ aq. as evident from spectral and redox potential values