Coffee Science - v.14, n.3, 2019

URI permanente para esta coleçãohttps://thoth.dti.ufv.br/handle/123456789/12417

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Ionic speciation in a dystrophic red latosol under coffee crop high doses of gypsum
(Editora UFLA, 2019-07-03) Ramos, Bárbara Zini; Lima, José Maria de; Serafim, Milson Evaldo; Coscione, Aline Renée; Ferraz, Raul Magalhães; Amorim, Lucas Mota; Lopes, Guilherme
The cultivation of coffe crops in Brazil, especially on Latosols, has been increasing over the years, despite limitations such as aluminum toxicity, low fertility and very long drought periods. In this scenario, soil amendments to mitigate these restraints are necessary. Since these limitations are not restricted to the arable layer, application of gypsum becomes an efficient alternative to sustain soil fertility and deepen the root system to get water from the deeper layers of soil. However, high doses of gypsum can cause unbalance among Ca 2+ , Mg 2+ and K + . The objective of this work was to evaluate these bases as well as their ionic pairs, and the presence of sulfate along the soil profile 16 months after the application of high gypsum doses in a Latosol under coffee crops. An inicial dose of gypsum was applied in the entire area, followed by four treatments, in triplicate and randomized blocks, set as follows: G0 - zero gypsum applied over the planting line after the initial soil preparation; G7- 7 t ha -1 of gypsum in the planting line (1.75 kg m -1 ); G56 - 56 t ha -1 of gypsum in the planting line (14 kg m -1 ), all with brachiaria between the coffee planting lines; and CV7 - 7 t ha -1 of gypsum in the line and no brachiaria between the planting lines. The soil profile was sampled in layers up to 2.40 m depth and the soil solution was extracted by suctioning the sample-saturated paste. Following this extraction, the soil solution was analyzed by combustion for total carbon contents, ion chromatography and ICP-OES/flame photometry, for chemical species, and speciation was done using Minteq software. After 16 months of gypsum application, 96% of K + in soil solution was at 0.35 to 0.45 m in its free form. Leaching of Ca 2+ and Mg 2+ occurred predominantly in their free forms, although a more significant contribution of CaSO 40 and MgSO 40 ionic pairs was observed when compared to K 2 SO 40.
Sites and sampling tools in the soil fertility evaluation of coffee plants in production
(Editora UFLA, 2019-07) Mantovani, José Ricardo; Lima, José Antônio; Garcia, Ciro Pozzi; Rezende, Tiago Teruel
In soil sampling, the collection site and the tool used may induce errors that can compromise the results of the chemical analysis and, consequently, the definition of corrective and fertilizer doses. The objective in this study was to evaluate soil sampling sites and tools in a coffee growing area. The experiment was carried out in a field in the municipality of Alfenas-MG, in a 35-year coffee field. A randomized block design was used in a 3 x 5 factorial scheme and 4 replications, totaling 60 experimental units. The treatments consisted of 3 sampling sites: in the fertilizer strip (located in the projection of the plant canopy); between rows; and in the total area, with 1/3 of the samples collected under the canopy and close to the plant stem, 1/3 in the canopy projection and 1/3 collected between rows; and 5 sampling tools: Dutch auger; screw auger; probe; hoe and drill. Soil samples were collected at a depth of 0 to 0.2 m, and each composite sample was obtained by assembling and mixing 20 single samples. At each sampling point, an area of 2m 2 was delimited, in which simple samples were collected in all the evaluated places and with all the tools used. The following parameters were determined in the soil samples: pH in CaCl 2 ; potential acidity (H+Al); organic matter; P, extracted by Mehlich; K+, Ca2+, Mg2+ and base saturation. In a coffee-growing area, the fertilizer strip (canopy projection) has topsoil with higher acidity and lower contents of organic matter and nutrients P, K+, Ca2+ and Mg2+ than between rows. The tools used for soil sampling do not influence the results of soil chemical analysis in the coffee-growing area.