Soil conditioner effects on soil erosion, soil structure and crop performance
AbstractPrevious work has suggested that soil conditioners can provide environmentally beneficial aids to agriculture and soil conservation. To investigate this further, studies were carried out on soil conditioner effects on soil erosion, soil structure and crop performance. The main soil conditioner investigated was an anionic, hydrophilic conditioner based on ammoniurn-laureth-sulphate. Several objectives were established, in order to test the hypothesis that ammonium-laureth-sulphate can establish treatment effects by decreasing soil erosion and improving soil structure and crop performance. Subsequently, initial attempts were made to elucidate the mode of action. The field experiments were established on loamy sand soil (Bridgnorth series) at the Hilton Experimental Site, east Shropshire and on sandy silt loam soil (Salwick series) at the Plant and Environment Research Unit at Compton Park, Wolverhampton. The main soil conditioner applied was 'Agri-SC' at manufacturer recommended application rates and three other soil conditioners were used for some comparative studies. Following applications of ammonium-laureth-sulphate to bare and cropped plots, effects on the topsoil (0-5 cm) included significantly decreased bulk-densities, soil moisture contents and splash erosion and significantly increased soil porosity and infiltration rates. Other effects included decreased runoff and erosion rates from 100 slopes and penetrometer resistance and increased aggregate stability and drainage capacities. Responses in a winter wheat crop (cv. Beaver) included apparent suppressed seedling emergence, followed by apparent enhanced growth and development. Initial laboratory studies indicated conditioner treatment altered cation exchange capacities, mineral and elemental compositions and provided evidence for chemical interparticle bonds. ' The soil conditioner appeared to function through a mechanism involving several stages. Upon application, the charged polymer molecules were electrostatically attracted to clay or silt particles and their attached ions. It is postulated that ammonium ions could then replace Ca and possibly Mg and Na, causing the polymer molecules to adhere to soil particles. This might be associated with mineral deposition. The laureth polymer strings could thus bridge individual particles and increase internal aggregate stability. This mechanism may be relevant for further understanding of the mode of action of other hydrophilic, polymer-based soil conditioners.
PublisherUniversity of Wolverhampton
TypeThesis or dissertation
DescriptionA thesis submitted in partial fulfilment of the requirements of the University of Wolverhampton for the degree of Doctor of Philosophy
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