Introduction du haricot mongo (Vigna radiata L.) comme précédent cultural pour améliorer la disponibilité de l'azote et le rendement du riz pluvial dans le Nord Est de la Thaïlande

La revue Australian Journal of Agricultural Research devient en 2009 la revue Crop & Pasture Science (nouvel ISSN-L 1836-0947)International audienceOne possible management option for farmers to improve the soil nitrogen (N) supply for rice production is the cultivation of a prior legume. The objective of this study was to investigate the value of such an option in the lowland of the north-east of Thailand. Two experiments were established in 2 typical locations in a split-plot design with 4 replicates. The main plots included 3 nitrogen levels (0, 30, and 60 kg N/ha) and the subplots, 4 pre-rice managements: (i) fallow with weeds removed (FW–); (ii) with weeds incorporated before the rice crop (FW+); (iii) mungbean incorporated at .owering as green manure (MGM); or (iv) incorporated after grains harvest (MR+). In both experiments the difference in rice yield between MGMand MR+ was not significant. In Expt 1, in contrast to Expt 2, the rice yield increase due to MR+ was significant and significantly higher than that due to application of 60 kg N/ha. Moreover, significantly higher apparent recovery of N (ANRm, kg N uptake increase/kg N supplied by residues), probably due to the continuous .ooding of the soil surface, was achieved in this experiment. The low values of internal efficiency of N (IEN, kg total grains/kg total N uptake), ANRf (_kgNuptake/kg N supplied by fertiliser), and of ANUEf (_kg grains/kg applied N fertiliser) recorded in the MR+ treatment of Expt 1, suggest that no application of N fertiliser is needed where the soil water conditions allow high recovery of the N supplied by a preceding mungbean crop