Effect of limestone doses incorporated at 40 cm on the availability of nutrients, root growth, and productivity of annual crops

Abstract

Soil acidity is one of the greatest barriers to increasing productivity under tropical conditions since it is directly associated with low nutrient levels. The use of limestone in adequate doses is considered the primary way to improve soil fertility and plant nutrition. However, there are doubts about defining the correct doses of corrective agents. Thus, this study aimed to evaluate the effects of incorporating limestone at 0 to 40 cm on the chemical attributes of the soil, availability of macro and micronutrients, development of second-crop corn roots, and annual crop productivity. Three experiments were implemented in different locations (2017) using five doses of limestone (0, 3, 6, 9, 12, and 15 Mg ha-1) incorporated in the 0-40 cm layer. Soybeans, corn, beans, and wheat were cultivated over the years. Soil samples were always collected at the end of the spring/summer harvest, and leaf samples were collected at the flowering stage of the crops grown during the spring/summer harvest. The roots were evaluated in 2020, during the second harvest of corn crop intercropped with Brachiaria ruziziensis up to 60 cm deep. Doses above 9 Mg ha-1 significantly increased the levels of Ca2+, Mg2+, and pH and base saturation values, consequently promoting greater development of the root system of corn intercropped with Brachiaria ruziziensis up to 60 cm deep. There was a positive correlation between pH and macronutrient absorption. No effect of liming on soil Zn content was observed. However, Fe presented themost significant reduction in soil availability due to liming. The concentrations of B, Fe, Mn, and Zn in soybean and bean leaves were reduced with increasing lime doses. However, they remained within adequate levels. Relative productivity of 95% was achieved when 80% and 52% of the potential CEC in layers from 0 to 20 and 20 to 40 cm, respectively, were occupied with Ca + Mg, demonstrating the need to review current methodologies of limestone recommendations. Finally, the liming incorporated in the 0-40 cm layer improved the root environment, allowing crops to express their productive potential.