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Evaluating the impact of rising fertilizer prices on crop yields

Brunelle T., Dumas P., Souty F., Dorin B., Nadaud F.. 2014. In : 4th Sustainable Phosphorus Summit : book of abstracts, Montpellier, France, 1-3 september 2014. s.l. : s.n., 1 p.. Sustainable Phosphorus Summit. 4, 2014-09-01/2014-09-03, Montpellier (France).

The agricultural land application of biosolids (stabilised solid organic residuals from treated sewage sludge) as a source of nutrients for crop production is considered a long-term sustainable management option throughout many regions in Australia. Approximately 70% of the 330,000 tonne dry solids produced nationally are land applied per annum. The phosphorus (P) content of biosolids varies and is dependent on the wastewater treatment process, with mean total P values of 1.3-3.9% reported throughout Australia. It is estimated that approximately 6,000 tonne of P is returned to the soil annually in Australia from the land application of biosolids. Hence the recycling of P from biosolids is a useful substitute for inorganic fertiliser P and prevents the loss of P from the food chain. This paper presents findings for P availability in four biosolids products (dewatered mesophilic anaerobically digested, lime-amended, pelletised and alum sludge) relative to inorganic P fertiliser as investigated by combinations of field crop, laboratory and pot experiments in south-western Australia over several years. The risk of off-site movement of biosolids-P compared with inorganic fertiliser P at typical application rates was further examined on several soil types to assess the environmental implications of this practice in Australia. The effectiveness of biosolids-P compared to inorganic-P as a source of fertiliser in field experiments as measured by soil available P, uptake of P by shoots and crop yield was dependent on many factors over time including the soil conditions and biosolids type. Biosolids produced from wastewater treatment processes that used aluminium treatment to remove excess P had lower phytoavailability than those without chemical addition and pose additional challenges for land application as a source of P. (Texte intégral)

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