Yield of soybean-wheat succession in no-tillage system and soil chemical properties affected by liming, aluminum tolerance of wheat cultivars, and nitrogen fertilization

Subsurface soil acidity and nitrogen (N) shortage are challenging for wheat (Triticum aestivum L.) and soybean (Glycine max L.) crops under no-tillage system. The aim of this study was to evaluate the yield of soybean-wheat succession in no-tillage system and soil chemical properties affected by liming, aluminum (Al) tolerance of wheat cultivar (WC), and N fertilization in southern Brazil. A 2 x 2 x 4 factorial arrangement was used: two liming rates (0 and 2 Mg ha(-1) - applied at the beginning of trial installation), two WC (CD 150: Al-sensitive; and BRS Gralha-Azul: Al-tolerant), and four N rates (0, 40, 80, and 120 kg ha(-1) N as NH4NO3, applied annually to wheat). Soil chemical analysis (at 0.00-0.10, 0.10-0.20, and 0.20-0.40 m layers) including pH, H+Al, Al3+, P, K+, Ca2+, Mg2+, soil organic matter (SOM), and base saturation (V) were performed 24 months after liming, in addition to evaluation of wheat and soybean grain yields at each growth season. Liming increased Ca2+, Mg2+, and V up to 0.40 m depth; increased pH and decreased H+Al only at the topsoil; and had no effect on K+, P, and SOM. Compared with Al-sensitive WC, Al-tolerant WC decreased Al3+ up to 0.40 m soil depth. Al-sensitive WC pre-ceding soybean decreased the relative soybean grain yield, particularly without liming, regardless of the N rates. Nitrogen fertilization decreased K+ at 0.00-0.10 and 0.10-0.20 m soil layers, and Mg2+ at topsoil (without liming), increased Al3+ at all soil layers, but did not change soil pH. There were several interactive effects be-tween liming, WC, and N rates. For instance, the increase of Al3+ due to N fertilization was intensified when combined with no lime application or with Al-sensitive WC. Despite soybean crop being generally non-responsive to N fertilization, N rates applied to the previous wheat crop increased soybean yield in the first two crop seasons. The different pattern of response related to soil properties is mainly attributed to the particular mobility or solubility of each element into the soil, which is influenced by the soil pH, accompanying anion during leaching process, among other factors. The role of genotype tolerance to acidic soils as complementary strategy to liming brings benefits to the agricultural system by improving the soil chemical quality.