Clay addition to sandy soil: effect of clay concentration and ped size on microbial biomass and nutrient dynamics after addition of low C/N ratio residue

• Shermeen Tahir ^[1] ; Petra Marschner ^[1]
  1. [1] University of Adelaide

     University of Adelaide

     Australia

     
• Localización: Journal of soil science and plant nutrition, ISSN-e 0718-9516, ISSN 0718-9508, Vol. 16, Nº. 4, 2016, págs. 864-875
• Idioma: inglés
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• Resumen

  • Addition of clay-rich subsoil to sandy soil has been shown to increase crop production on sandy soils. The added clay is present as peds ranging in size from a millimetre to several centimetre. In this experiment clay soil (73% clay) was added to sandy soil (3% clay) at 10 and 20% clay w/w as 1, 3 and 5 mm peds. Shoots of young Kikuyu grass (C/N 20) were ground and added at 10 g kg-1, and soils were incubated for 45 days at 80% of water holding capacity. The study confirmed that clay addition to sandy soil increased soil organic carbon retention but decreased cumulative respiration and available P compared to sandy soil alone. Ped size had little effect on respiration and nutrient availability. Over the course of 45 days peds broke down and organic C was bound to the < 53 µm fraction. The greatest proportion of peds and total organic carbon (54-67%) was in the initially added ped size. The TOC content of < 53 µm fraction of initially added peds was 0.38% and at the end of the experiment (after 45 days) the TOC had increased by 24, 19 and 10% in 1, 3 and 5 mm peds respectively.