Influence of surface‐applied poultry manure on topsoil and subsoil acidity and salinity: A leaching column study |
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Authors: | Richard J Haynes Angus Judge |
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Institution: | 1. School of Land, Crop and Food Sciences/CRC CARE, The University of Queensland, St Lucia, Queensland 4072, Australia;2. ARC‐Institute for Soil, Climate and Water, Cedara Research Station, Pietermaritzburg 3200, South Africa;3. present address: Environment Waikato, P O Box 4010, Hamilton, New Zealand |
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Abstract: | It has been suggested that surface applications of animal manure can ameliorate both top and subsoil acidity. For that reason, the effects of surface incorporation (0–5 cm) of a high rate of poultry manure to an acid soil on pH and exchangeable and soluble Al in the top‐ and subsoil were investigated in a leaching column study. During the experimental period of 108 d, columns received a total of 875 mm with leaching events occurring after 9, 37, 58, and 86 d. Incorporation of poultry manure into the surface 5 cm resulted in a large rise in pH measured in both 1M KCl and in soil solution. This liming effect was attributed primarily to the substantial CaCO3 content of poultry manure. In the 15–45 cm layer, pHKCl was not significantly different between poultry manure and control treatments but surprisingly, soil‐solution pH was substantially less in the poultry‐manure treatments. Exchangeable Al was significantly less in poultry manure than in control in all soil layers although the effect was most marked in the 0–5 cm layer. However, although concentrations and activities of monomeric Al (Almono), and the proportion of total Al present as Almono, in soil solution were lower under poultry manure than in control in the 0–5 cm layer, the reverse was, in fact, the case in lower soil horizons. This was attributed to a soluble‐salt effect, originating from the large cation content of poultry manure, displacing exchangeable Al3+ and H+ back into soil solution. Indeed, electrical conductivity and concentrations of Ca2+, Mg2+, K+, and Na+ in soil solution were substantially higher in the poultry‐manure than in the control treatments at all soil depths. Poultry‐manure applications also resulted in substantial increases in the concentrations of Ca2+, Mg2+, K+, Na+, Almono, NH , and NO in leachates, particularly at the fourth leaching. It was concluded that although surface application of poultry manure can raise soil pH in the topsoil, increases in soluble‐salt concentrations in soil solution can greatly modify this effect in the subsoil. |
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Keywords: | exchangeable Al monomeric Al soil pH leaching |
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