Effects of liming and post-pruning subsoiling of coffee on soil chemical and physical properties and on crop yield

Abstract

Liming is the agronomic practice used to correct soil acidity, neutralize aluminum (Al), provide calcium (Ca) and magnesium (Mg), and improve nutrient availability. However, in already established coffee plantations, lime is generally applied only on the surface, without incorporation, since it is impossible to till the soil occupied by the plant root system. In such cases, reduced lime doses are usually applied due to the risk of a sharp increase in soil pH in the surface layer, with a consequent reduction in micronutrient availability. At some point in coffee production, severe pruning of the plants is recommended, which causes the death of more than 80% of the roots. This moment can be an ideal opportunity for soil management, since the roots have already been affected. Thus, this is a chance to improve soil conditions more efficiently. Therefore, the objective of this study was to evaluate the effect of different lime doses applied to the surface, followed or not by subsoiling after coffee tree stumping, on the chemical and physical attributes of the soil and on crop yield. The experimental design was a randomized block design with split plots and three replications. The main plot corresponded to lime doses (0, 1.5, 3, 6, 12, and 24 t ha−1), and the subplot corresponded to the use or not of subsoiling. Soil samples were collected to evaluate chemical attributes, pH, potential acidity (H+Al), base saturation (V%), Ca and Mg contents, and micronutrients, as well as physical attributes, such as water-dispersible clay (WDC), flocculation index (FI), porosity, and soil density. Leaf samples were collected to evaluate macro- and micronutrient contents over three years, as well as yield in the first two harvests after stumping. Regression analyses were performed to assess the effects of doses and application method on the chemical and physical attributes of the soil, as well as macro- and micronutrient contents in the leaves and coffee yield. Soil fertility was affected by the lime doses in all evaluations, and subsoiling contributed with its effects in some layers, including the 40–60 cm layer in the third year of evaluations. The micronutrients in the soil most affected by the lime doses were Cu and Fe. In turn, Zn and Mn levels in the soil were not altered by liming. The physical attributes were mainly affected from the second year of evaluations onward. Leaf concentrations of macro- and micronutrients were not affected by the lime doses or by subsoiling after corrective application. Even with the improvements in the soil, coffee yield was not affected.