Effect of manganese spatial distribution in the soil profile on wheat growth in rice–wheat rotation

Abstract

Manganese (Mn) deficiency in wheat under rice (Oryza sativa L.) and wheat (Triticum aestivum L.) rotation is an important problem in most rice-growing areas in China. A field survey, field trials and a soil column experiment were conducted to determine the relationship between Mn leaching and distribution in soil profiles and paddy rice cultivation and the effects of Mn distribution in soil profiles on wheat growth and its response to Mn fertilization. At five field sites surveyed, total Mn and active Mn concentrations in the topsoil layers under rice–wheat rotations were only 42% and 11%, respectively, of those under systems without paddy rice. Both total and available Mn increased with soil depth in soils with rice–wheat rotations, showing significant spatial variability of Mn in the soil profile. Manganese leaching was the main pathway for Mn loss in coarse-textured soil with high pH, while excessive Mn uptake was the main pathway for Mn loss in clay-textured and acid soil. When Mn was deficient in the topsoil, sufficient Mn in the subsoil contributed to better growth and Mn nutrition of wheat but insufficient Mn in the subsoil resulted in Mn deficiency in wheat.