**3. Porosity, water retention and availability in soils cultivated with coffee**

The presence of an ideal pore network with a wide range of diameters is one of the key factors for high crop yields, especially those most demanding for water, such as coffee [21, 40]. Soil pore diameter and distribution interfere with drainage ratios, available water content, ion adsorption, root growth, aeration and temperature, acting directly on physical-water phenomena, being an indicator of soil quality [41–43].

Since soil mineral composition influences pore shape, length and connectivity, soils of oxide mineralogy, such as the very weathered Cerrado Latosols, tend to have a very strong, well-connected microgranular structure with large pore formation. There is formation of thinner and elongated pores [2, 27, 28, 43–45], which has implications on the water content available to plants.

When used in some production process such as food, fiber or energy, some structural change must occur, modifying the distribution and connection of their pore networks and, consequently, promoting changes in the soil air-water dynamics. In this sense, conservation agriculture [13] has as its principle the physical and chemical improvements of the root environment, by reducing soil tillage and maintaining living or dead surface cover. Thus, it minimizes the compressive and erosive processes, in addition to the oxidation of organic material, promoting the vertical growth of the root system of crops.

With these simple conservationist measures, coupled with the chemical corrections of acidic Latosols, improvements in the physical environment are expected, favored by the good development of the coffee roots, particularly by the reduction of restrictive impediments to the vertical growth of its roots and access to stored water [6–8, 29] (**Figure 9**).

Thus, the conservationist soil management system described by Serafim et al. [10] promoted changes in water retention in very weathered Latosols. According to Carducci et al. [2], the system was able to alter pore scaling such that it increased in the layer of 0–0.20-0.34 m the volume of large macropores (>147 μm) in kaolinitic Latosol and increased the intermediate diameters (73–2.9 μm), which are pores responsible for the gradual release of water to plants [43, 46]. There was also no limitation to aeration in soils (>147 μm: ≈ 15%), because the values were within the acceptable range for gas exchange maintenance (**Figure 9**).

According to Carducci et al. [2, 47, 48], genetically weathered Latosols present a large amount of interconnected structural pores, which facilitate drainage. Textural pores (including cryptopores) are responsible for water retention of high energy

[2, 43, 46, 49] However, because it was submitted to the conservationist management system, there was a small increase in the intermediate pores when compared to the greater depth evaluated in both soils, especially the one with gibbsite.

There is higher water retention in the cryptopores of gibbsitic Acrustox (pores with diameter < 0.01 μm) due to the high energy (3500 kPa), which makes this water unavailable to the roots of coffee trees [48, 49] (**Figure 9**).

The authors mentioned in the previous paragraph point out that deep preparation and maintenance of Brachiaria sp. should be considered as the main factors of this management system. The additional surface applied gypsum (7 kg m<sup>−</sup><sup>1</sup> ), act as the supporting factor in the structure of the soils. Carducci et al. [6], when evaluating the same soils in 3D images obtained by X-ray computed tomography, verified that kaolinitic Latosols presented high spatial variability of the soil structure. These pores resulted from the rapid and well-branched growth of the coffee root system [7, 8]. This is extremely relevant information given that the interactions between soil and root have been considered as a key element for the second green revolution aimed at maximizing production [50].
