Agronomic effectiveness of lime and phosphogypsum for soybean in a Cerrado Soil

The Brazilian Cerrado is located in areas of tropical and subtropical climate, where the acidic soils are characterized by low pH, low organic matter, low levels of exchangeable calcium (Ca) and magnesium (Mg), low base saturation index, and relatively high exchangeable aluminum. Only with the practice of liming and fertilization was it possible to establish commercial agriculture in this important Brazilian biome. Liming contributes to the increase of the efficiency of the fertilizers and to crop productivity and agricultural profitability. Several studies have shown that liming in soils with high acidity results in the doubling of crop yields.

The acidity of the subsoil can be minimized with the use of gypsum (calcium sulfate). The use of limestone and gypsum has provided positive results on crop productivity in Cerrado acid soils, and gypsum can also help relieve the toxicity of aluminum in subsurface soil. Considering the increasing adoption of use of gypsum, and also the necessity of use of limestone in Latosols in the south of Piauí, this research objective was to evaluate the use of limestone as a corrective for soil acidity and gypsum as source of Ca and sulfur (S) in soybean cultivation in southern Piauí.

The experiment was installed at Fazenda União Serra das Laranjeiras, municipality of Currais, southern Piauí. The soil of the experiment area was characterized as a Dystrophic Yellow Latosol. Before the application of limestone and gypsum, analysis of the chemical and physical attributes of the soil were carried out. The treatments were a factorial combination of limestone (0, 2, 4, and 8 t/ha) and gypsum (0, 1, 2, and 4 t/ha), for a total of 16 treatments.

The results revealed that: (i) there was an interaction between limestone and gypsum doses that improved soybean nutrition and yield; (ii) limestone and gypsum promoted increases in the yield of 100 soybean grains and soybean leaf calcium contents; and (iii) the application of limestone showed no influence on leaf nitrogen and phosphorus concentrations.