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Deep soil tillage and proper rootstock selection mitigate the root development limitations in Ultisol's Bt horizon, enhancing the citrus yield potential. This study evaluates the root spatial distribution of three Ponkan tangerine rootstocks in Ultisol under deep tillage alongside the physical-hydric attributes and plant measurements. The experimental area underwent furrow creation, subsoiling, and hole opening for planting. The treatments included three rootstocks: "Cravo Santa Cruz" (CSC), "Sunki Tropical" (ST), and "Citrandarin Índio" (CI). Under the Ultisol preparation, these rootstocks were compared to a native forest area (FA). Three years post-initial tillage, soil samples were collected at depths of 0–0.05, 0.35–0.40, and 0.45–0.50 m from the pre-established positions. The evaluation encompassed soil dispersive clay, available water, crop water use, plant measurement, and crop yield. The root evaluation utilized the crop profile method and 2D images, with subsequent surface mapping of the root variables, number (NR), and diameter (RD) analyzed via kriging geostatistical analysis. The Ultisol showed significant changes in its physical-hydric attributes regarding structural change and more excellent clay dispersion, with a considerable contribution to the micropore volume. Deep tillage effectively improved the root spatial distribution, especially concerning the number and diameter of roots, and enhanced the water use, reflected in the vegetative growth and yield, with the rootstock CSC standing out. [ABSTRACT FROM AUTHOR]

Deep tillage can be applied to face high-density soil horizons by improving the root system's access to deeper layers. In this sense, soil and ecosystem services related to nutrients cycling and water recharge can be improved. In this study, the spatial and temporal dynamics of soil water content (θ) were inferred using two-dimensional electrical resistivity (ER) surveys, that were applied to explore the soil profile treated by deep tillage under different citrus rootstocks (RS) implantation. A seasonal scale ER monitoring (Spring 2018, Summer 2019, and Winter 2019) was carried out at a selected study area, characterized by Ultisols and located in Southeastern Brazil. Three different citrus RS-types, represented by the varieties 'Cravo Santa Cruz lemon' (CSC), 'Sunki Tropical Tangerine' (ST), and 'Citrandarin Indio' (CI). Deep tillage was adopted before RS citrus-types planting by opening furrows and subsoiling up to 0.6 m depth. The interrows citrus plants were covered with Brachiaria decumbens (Syn. Urochloa) in all citrus RS-type plots. A native forest area ('Forest') was used as reference for all θ evaluations. The model for the ER-θ relationships was determined from measurements conducted on soil samples in the laboratory. Root water uptake (RWU), in terms of θ changes, was evaluated at the different treatments under study. The obtained results proved the suitability of ER method for identifying the ER-θ dynamics in the Ultisol profiles over time. Lower and more stable θ values were obtained in the 'Forest' and interrow areas. Among the evaluated citrus RS-types, CSC showed the highest water use efficiency due to the greatest root system development. [Display omitted] • ER is a useful technique for inferring the soil water content (θ) dynamics. • ER-θ adjusted models explain 45–80 % of the θ changes in Ultisol. • ER season-based analyses allow to compare θ dynamics under citrus rootstocks. • Greater root-water uptake (RWU) was indirectly related to lower θ. • Greater RWU was observed in CSC rootstock. [ABSTRACT FROM AUTHOR]

Highlights • Critical moisture for crop in each phenological stage was added as the lowest limit of LLWR. • Water uptake in soil profile improved with deep tillage, intercropping and additional gypsum. • Soil physico-chemical conditioning was important to maintain plant water status. • Unlike plants aerial growth, average yield of first years are the same among management systems. • Intercropping with Brachiaria reduces soil moisture but not lead water stress to Coffee plants. Abstract Water determines the success of coffee farming, since it influences the phenology of the plant and, consequently, its productivity, product quality and commercial viability. The Least Limiting Water Range (LLWR) associated with the monitoring of soil water content (θ) distinguishes management systems as to their effectiveness in supplying water to plants. The need for developing better management systems –in Brazilian rainfed farming– that promote water uptake by coffee plant radicular systems at lower soil depths where water is more available, inspired this study. This work had as an objective to evaluate the availability of water in soil through LLWR limits in association with leaf water potential, as well as growth and yield of coffee plants, in the Cerrado region of Southeastern Brazil over 4 years. The management systems evaluated were: CV-0 (conventional management with coffee interrow maintained with bare soil); G-28 (conservation management, with maintenance of Brachiaria in interrow, ridging and additional application of 28 Mg ha−1 gypsum applied in the rows) and G-7 (same as G-28, except for an additional application of 7 Mg ha−1 of gypsum). θ was monitored every 15 days. Critical moisture for coffee crop in each phenological stage was added as the lowest limit of LLWR. In all evaluated management systems, θ was below the critical moisture as measured at the soil depths of 0.20 m and 0.60 m. At 1.00 m depth in the CV-0 management system, the greatest value of θ was found, which caused the assumption of smaller water uptake. Regardless of the management adopted, the leaf water potential reached -1.16 MPa in August 2010, but that did not cause water stress high enough to reduce productivity. At 0.60 m depth, the lowest value for θ between rows was observed for the G-28 management system. Plants showed a more accentuated initial growth in the CV-0 management system. Each management system showed distinct behavior regarding productivity of the evaluated crops: in 2011, CV-0 had the highest productivity, but, in 2012, productivity was greater for G-7 and G-28. [ABSTRACT FROM AUTHOR]