1981
DOI: 10.1051/agro:19810912
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Elaboration du rendement et fertilisation azotée du blé d'hiver en Champagne crayeuse II. - Types de réponse à la fumure azotée et application de la méthode du bilan prévisionnel

Abstract: In a first approach, we note that the observed yields were often different from the objectives ( fig. 1). However, using grain number per unit area as a criterion of nitrogen efficiency, allowed us to analyse the cases of bad prevision. 4 types of response curves to nitrogen are distinguished (tabl. 5 and fig. 3 We conclude in favour of the validity of the tested method, which allowed to obtain, in 8 cases out of 10, when the yield objective was not over-estimated and the soil structure favourable, at least th… Show more

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Cited by 29 publications
(17 citation statements)
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“…Umax is the level ofN uptake at which yield reaches its maximal value Y max· The function is thus continuous at Umax· A quantity often of interest is b = Uma.IYmax. which is N uptake per unit of yield, evaluated at the start of the yield plateau (Meynard et a!., 1981). To include this parameter explicitly in the model, we replace the parameter Umax by b Ymax· The parameters to be estimated are then a, b, and Ymax· The second yield model is a quadratic-plus-plateau model (YLD-QP), defined by…”
Section: Intermediate Models Yield As a Function Of N Uptakementioning
confidence: 99%
See 1 more Smart Citation
“…Umax is the level ofN uptake at which yield reaches its maximal value Y max· The function is thus continuous at Umax· A quantity often of interest is b = Uma.IYmax. which is N uptake per unit of yield, evaluated at the start of the yield plateau (Meynard et a!., 1981). To include this parameter explicitly in the model, we replace the parameter Umax by b Ymax· The parameters to be estimated are then a, b, and Ymax· The second yield model is a quadratic-plus-plateau model (YLD-QP), defined by…”
Section: Intermediate Models Yield As a Function Of N Uptakementioning
confidence: 99%
“…Both terms are estimated from soil and crop characteristics and fertilizer N is then calculated to supply the shortfall. According to Meynard et a!. (1981Meynard et a!.…”
mentioning
confidence: 99%
“…Nutrient solutions (see Moreau et al , for the detailed composition) were provided by automatic watering of pots several times a day at a frequency that allowed the pots to drain freely, thereby avoiding the accumulation of ions in the substrate. We recorded daily watering in Experiment 2 (without considering draining) to draw a parallel with the orders of magnitude of amounts of nitrogen in field conditions (Meynard et al , ). During the experiment, each pot received, on average, the equivalent of approximately 22–27 kg ha −1 at low soil‐nitrogen availability (i.e.…”
Section: Methodsmentioning
confidence: 99%
“…The "Champagne Céréales" cooperative members tend to represent the "big" cereal growers of the region, whereas the Agricultural Board is more concerned with mixed croplivestock farmers, whose specialisation towards cash crops has not begun or is just beginning; -they may have received different training: "Champagne Céréales" advisors may have been taught about the early experiments in the Champagne crayeuse of the Marne department. For example, in the late seventies, INRA did research on technical sequences on winter wheat in the "Champagne crayeuse" small agricultural district [7,19]. These studies may have been more rapidly known by the "Champagne Céréales" advisors, as the cooperative used to working in the Marne and Meuse departments, than by the advisors from the Meuse Agricultural Board;…”
Section: Consequences Of the Choice Of The Experts In The Survey Designmentioning
confidence: 99%