Improvement phosphate fertilising practices in carrot crops

Vegetable species are generally classified in the category of plants with high phosphorus (P) requirements. Such is the case for carrot, and the no-fertilisation threshold is 70 mg P?O? (Olsen)/kg soil for crops in Sandy soil. Current practices are based on that value, but there has been no validation of the initial hypothesis and the ensuing practices. Four trials were conducted in the Aquitaine region (southwest France), a major growing area characterised by organic sandy soils with acid pH, in order to analyse the crop?s response to a wide range of P levels in the soil. The resulting response curves show that the current P?O? (Olsen) threshold is too high in relation to the actual requirements of carrot crops. New indicators of phosphorus bioavailability, based on water-soluble P dynamics, were evaluated in spring and summer crops, and experimental references were established. As a result, the minimum P concentration of the soil solution, defined by the Cp indicator, is evaluated at 1 mg P/l. Above said value, carrot crops show no loss of yield. This response threshold, currently under validation for the diversity of agronomic situations, indicates true potential for progress in phosphate fertilisation practices. Furthermore, the trials have made it possible to determine the optimum P consumption level, i.e. 26 kg P/ha or 60 kg P?O? /ha (for 50 t of commercial production); excess P will not enhance crop yield or quality. Finally, soil reserves represent a significant source of P. For instance, in soil considered as phosphorus-poor (20 mg P?O? ??Olsen/kg soil), more than half of the phosphorus used by the crop to ensure optimum yield is supplied by the soil?s own resources. The newly acquired knowledge and technical references offer a means to update P fertilising practices in carrot crops which, based on the results of this study, may be used as a model for extension to other species. ? Original tittle, authors and sources Updating phosphate fertilising practices in carrot crops Raynal Lacroix C.(1), Denoroy P.(2) (1) CTIFL,Centre de Lanxade, Prigonrieux F-24130 (2) INRA UMR TCEM, Domaine de la Grande Ferrade, Villenave d?Ornon F-33883 Carrot and other Apiaceae International Symposium, 17-19 September 2014, Angers, France,?http://www.symposium-carrot-apiaceae2014.fr/ Picture by?www.flickr.com ? Key wordsPoscosecha??????? postcosecha????? postharvest?????? na-oes? ???????????????????????????????????? post-r?colte?????????????????????????????????????????????????? na-oogst???????????? post-raccolta???? Obr?bka po?????? p?s-colheita????????????????????????????? hasat sonras????? ??????????????? Ernte???? ????????????????????????? ?????????????????????? postcollita?????????? poskliz?ov頠???? ?????????????????????????????????????? nakon branja???? pozberov頠?????????????????????? obdelovanje zemlje po??????????????? post-colleita????? ??????????????? pascapanen????????????????il?onn postharvest???????????????????? p?c ra?as???????????? derliaus apdirbimas polepas tuai?????????????????????? post-recoltare????????????????????????????????????????????????????????????????????????????????????????????????? sau thu ho?ch????????????????????????????????????????????? zangemva kwenkathi yokuvuna Zanahoria???????????????????????? carrot??? wortel????????????????????????????? karoto? carotte????????????????????? ??????????????????????? carota?? marchew??????????? cenoura????????????????????????????????? havu砠??????????????????????????????