%0 Journal Article
%T Effects of Paper-Mill Sludge as a Mulch versus Topsoil Incorporation on Potassium Uptake and the Grain Yield of Rain-Fed Wheat in a High Specific Surface Loess Soil with Illite Dominance in Clay Fraction
%A S. Amini
%A S. A. R. Movahedi Naeini
%A K. Mashayekhi
%J Applied and Environmental Soil Science
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/624824
%X A field experiment with rain-fed winter wheat investigated the nutritional aspects of paper-mill sludge as a mulch and incorporated into the topsoil. Treatments with chemical fertilizers were also used as controls. Paper-mill sludge used as mulch with high rate (100£¿MG£¿ha£¿1) and also the combined N and K mineral fertilizer treatments increased yield when a low potassium otherwise caused potassium deficiency in wheat with high specific surface soil. High soil Ca£¿:£¿K molar ratio by incorporation lowered potassium uptake and yield, with visual symptoms of potassium deficiency. A very high Gapon selectivity coefficient (KG) for K exchange against Ca£¿+£¿Mg (16.58£¿(L/mole)0.5) produced a nonlinear normalized exchange isotherm in favor of potassium with these soils containing high illite. Ca and K which are released by sludge decomposition are diverged in soil when mobilized by rain infiltration, lowering Ca£¿:£¿K molar ratio. Low soil Ca£¿:£¿K molar ratio may be expected by surface sludge application relative to incorporation, due to greater rain infiltration through upper soil layers and their effluent pore volumes per unit depth. Ca from triple superphosphate by the P, N, and K mineral fertilizers combined also reduced potassium uptake and yield relative to N and K combined. 1. Introduction The application of organic residues at or near to the surface as mulches or incorporated in the topsoil influences the behavior of soil water and temperature regime and supplies additional nutrients for crop growth. Soil physical and nutritional limitations are enhanced by marginal rain and temperatures due to more limited root growth [1] or transfer of ions from soil to roots [2]. Limitations of phosphate supply and un-sustainability of fossil-fuel-based fertilizers and their transport cost add to the significance of organic residues for agricultural use [3]. They also contain a large quantity of potassium [4]. A combined sludge from Mazandaran Mill (Iran) was used in this research. Three different methods are used commercially to break down wood fiber (comprised principally of cellulosic compounds) mechanically or chemically to create wood pulp. Mechanical mills use stone discs (with or without heat) to grind the fibers. Kraft mills use sodium hydroxide and sodium sulphide to break down the fibers, while sulphite mills use calcium sulfite, magnesium sulfite, or ammonium sulfite [5]. Many mills use chlorine to bleach the paper, while other mills use hydrogen peroxide [6]. Solid wastes arising from above processes, commonly referred to as sludges, are available in three
%U http://www.hindawi.com/journals/aess/2012/624824/