Grahmann, K.; Verhulst, N.; Peña-Bautista, R.J.; Buerkert, A.;Vargas-Rojas, L.; Govaerts, B.
Little is documented about the effect of different tillage and residue management practices on durum wheat (Triticum durum L.) quality. This study aims at examining the effect of tillage–residue management systems on wheat yield and quality in two cropping cycles, 19 years after establishment of tillage–residue management systems in 1992. Wheat grain samples were collected in an experiment with a durum wheat-maize (Zea mays L.) rotation and furrow-irrigation, conducted in the arid Yaqui Valley of north-western Mexico. Main plots had five tillage–crop residue management treatments: conventionally tilled raised beds (CTB) with straw incorporated and permanent raised beds (PB) with straw burned, removed, partly retained or fully retained. Split plots had seven nitrogen (N) fertilizer treatments with different rate (0, 150 or 300 kg N ha−1) and timing of application (basal, 1st node and split between both). Highest yields were obtained with PB-straw partly retained and 300 kg N ha−1 split application in 2010/11 (7.48 t ha−1) and with PB-straw removed and 300 kg N ha−1 applied at 1st node in 2011/12 (8.26 t ha−1). Permanent beds with full residue retention had high yellow berry (YB, opaque and starchy endosperm) incidence, even with 300 kg N ha−1; 19.5% in 2010/11 and 9.4% in 2011/12 of the grain kernels were affected by YB. Four groups of tillage–straw systems with different characteristics in relation to the durum wheat quality and yield were distinguished with a principal component analysis: PB-partly retained with high yields and acceptable quality, PB-straw retained with low quality and acceptable yields, CTB with intermediate quality results and lower yields and PB-straw burned with high quality and low yields. Results indicate a significant effect of timing of N application on durum wheat grain quality in PB. For both cycles and both N rates, the application of mineral N resulted in higher grain quality when all N was applied near 1st node. Grain quality was highest in PB-straw burned, but this practice had the lowest yields. For PB-straw fully retained, 1st node application of N fertilizer is recommended to minimize N immobilization. To obtain stable yields and desirable quality, alternative tillage practices such as PB with full or partial residue retention require adjusted, site-specific N management. Further research is required to identify fertilization strategies in tillage systems with full or partial residue retention that include fertilizer applications after first node to improve grain quality.
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