Very early sowing of winter oilseed rape improves its environmental balance without negative consequences on production | Des semis tres precoces de colza d'hiver ameliorent l'equilibre environnemental sans consequences negatives sur la production
1999
Dejoux, J.F. (Institut National de la Recherche Agronomique, Thiverval Grignon (France). Centre de Versailles Grignon, Agronomie) | Meynard, J.M. | Reau, R.
The research program aims at demonstrating that changing the sowing date could be a powerfull means to improve the environmental balance sheet of a winter rape crop. The hypothesis is that earlier sowing dates could enable rape to absorb more nitrogen in autumn and decrease soil N mineral before leaching. It was compared the effects of very early (end of July) and normal sowing dates (beginning of September) on N uptake and N leaching risk. This was assumed on experimental plots and under farm conditions. Potential N uptake before winter was increased by 150 kg N/ha with earlier sowing compared to normal sowing, and it may reach up to 300-350 kg N/ha for a standard year. This absorption was strongly correlated with leaf area index. In farm field-trials network, there were no major limitations to sow under dry conditions and absorption was dependent on N availability. Consequently, very early sowing decreased systematically soil N mineral content before leaching to a level of less than 30 kg N/ha for 90 cm depth, whereas it was very variable with normal sowing dates: 20 to 280 kg N/ha. Very early sowing may be of great interest to reduce N leaching, especially when N availability is high in autumn, like after sludge or slurry spreading
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تم تزويد هذا السجل من قبل National Institute for Agricultural Research