Proceedings of the International Soil Tillage Research Organisation 18th Triennial Conference
International Soil Tillage Research Organisation 18th Triennial Conference edition:18 location:Izmir, Turkey date:15-19 June 2009
End-of-season yield results do not permit the evaluation of within-season management interactions with the production environment and consequently do not allow full understanding of the applied management practice. Therefore, crop performance was measured twice a week during the 2007/08 crop cycle with a handheld NDVI sensor in a long-term trial established in 1992 under irrigated, arid conditions in northwestern Mexico. Different bed planting systems (conventionally tilled beds [CTB] and permanent raised beds [PB]) were compared for a wheat-maize rotation. Residue management varied from full to partial retention and burning. Nitrogen (N) fertilizer treatments differed in dose (0, 150 or 300 kg N ha-1) and time of application (basal or split application). Wheat crop development throughout the season clearly depends on tillage, crop residue management and amount and timing of N fertilization. Three tillage-straw systems could be distinguished based on their different effect on crop growth: CTB-straw incorporated, PB-straw burned and PB where straw was not burned. When no N fertilizer was applied, the CTB-straw incorporated took off fast compared to the PB systems, but plant performance decreased abruptly two weeks after the first auxiliary irrigation and was lower than in the PB where straw was not burned thereafter. When N fertilizer was applied, the high plant performance in CTB was maintained throughout the season. In the PB-straw burned, plant performance was lower throughout the season than in the other tillage-straw treatments when no N fertilizer was applied. When N fertilizer was applied, the initial growth in the PB-straw burned was equally fast than in the CTB-straw incorporated. However, later in the season plant performance decreased faster in the PB-straw burned than in the other tillage-straw treatments. When N fertilizer was applied, the PB where straw was not burned showed slower initial crop growth than CTB and PB-straw burned. The difference was more pronounced when more straw was retained. Increasing levels of N fertilizer resulted in plant performance closer to that of CTB-straw incorporated later in the season. Increasing the amount of N fertilizer increased plant performance in all tillage-straw treatments, but differences between N fertilizer treatments were small in the PB-straw burned. There is an important interaction between tillage/residue management practice and N fertilizer application practice that needs further research.