Comparing tillage methods for growing lowland soybean and corn during wetter-than-normal cropping seasons

Rice monocropping underutilizes the productive potential of lowland soils. A major challenge in cropping low-drainage soils, particularly in wetter-than-normal years, is improving drainage conditions of paddy soils to allow rotation with upland crops. The hypothesis tested was that chiseling and ridging improve soil physical environment in lowland soils for upland crops growth, development and yield, and that short-maturity soybean experiences greater stress from hypoxic conditions in lowlands soils subjected to high moisture in years of high rainfall. The aim of this study was to evaluate the influence of chiseling and ridging, compared with conventional tillage, in providing an improved soil environment for soybean and corn in Hapludalf (Planosols) soils in higher-than-normal rainfall cropping seasons. Experiments were carried out in two high-rainfall cropping seasons (2014/2015 and 2015/2016), in Hapludalf (Planosols) soils in southern Brazil, comprising four tillage methods (conventional, chisel, ridge, and chisel plus ridge) for soybean and corn crops. Soil physical properties were evaluated at sowing, 45 and 140 days after sowing, and plant variables were quantified. Chiseling alone or supplemented by ridge construction increased water infiltration rates by 3.0–10.5 compared with conventional and ridge tillage. Chiseling increased soybean and corn yields, while ridge construction did not differ from conventional tillage, and short-duration soybean group was the least productive. In years of high rainfall, chiseling improves soil physical and hydraulic properties, but excessive rainfall lessens the benefits of tillage and ridging. In conclusion, although chiseling significantly increases soybean and corn yields in lowlands, either an isolated practice or associated with ridge construction, the two wetter-than-normal years clearly show crop yield is highly dependent on the crop development stage when hypoxia occurs in root zone.