Improving soil quality and plant growth in dense cambisol: long-term effects of deep tillage in coffee cultivation

Abstract

The demand for land for coffee cultivation has increased due to the popularity of this beverage, including in soils with physical and hydric restrictions, such as Cambisols. Although most plantations are in rainfed areas, management strategies to optimize soil water use are crucial. Investment in initial preparation technology, such as opening deep planting furrows, is essential to ensure long-term success and improve the physical-hydric quality of the soil. In this context, three studies were conducted in an experimental area of Cambisol in Nazareno, Minas Gerais, Brazil. Soil preparations are distinguished concerning the opening of the planting furrow: SP40 (up to 0.40 m through the furrower); SP60 (up to 0.60 m by Big Mix, soil homogenizer); SP80 (up to 0.80 m through Dreno, subsoiler) and distinguished in terms of chemical correction in depth by additional liming (SP60AL; SP80AL) or by mixing with gypsum, serpentinite and natural phosphate (SP40M; SP60M; SP80M). The first study analyzed the effects of different deep tillage strategies and chemical correction of the planting furrow on soil physical quality and growth of coffee plants over five years. The results showed that the preparation of the deep furrow by the subsoiler (up to 0.80 m) in combination with additional liming promoted improvements of up to 0.40 m in depth in the soil, favoring the growth of the coffee plant. The second study investigated the relationship between soil preparation and the practice of additional liming concerning the Cambisol's physical quality and the coffee plant's antioxidant protection under two periods (dry and wet). Up to 0.60 m tillage without additional liming showed advantages, such as aggregation, lower soil resistance to penetration, more remarkable root development, and less water storage during the dry period. This preparation also resulted in more significant enzymatic activity of the antioxidant system, with less hydrogen peroxide and lipid peroxidation, evidencing its efficiency in the drought tolerance of the plants under this preparation condition. The third study used X-ray computed tomography to quantify structural changes in the Cambisol resulting from different soil preparation strategies and their impact on coffee growth. Deep tillage with a subsoiler, combined with specific chemical corrections, conditioned significant effects in effectively changing the structural characteristics of this shallow and naturally dense Cambisol, promoting the growth of coffee plants. Thus, the results of the three studies highlight the importance of deep opening the planting furrows and decision-making at the time of initial soil preparation, especially with the use of a subsoiler, to avoid losses in the physical-hydric structural quality of the Cambisol. In this way, the deep opening of the soil, combined with adequate chemical corrections, improves the Cambisol's physical-hydric quality and optimizes the coffee plant's development. These strategies are beneficial and, therefore, essential for the success of coffee cultivation in restricted soils, resulting in more significant growth and better adaptation to field conditions under rainfed conditions.