Banca de DEFESA: JONAS OLIMPIO DE LIMA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : JONAS OLIMPIO DE LIMA SILVA
DATE: 21/09/2022
TIME: 14:00
LOCAL: Videoconferência - meet.google.com/rus-iwsk-hjt
TITLE:

Cover crops affect the mineral nutrition of cocoa in full-sun cultivation system

KEY WORDS:

Theobroma cacao L, nutrient cycling, green manure, soil cover

PAGES: 40
BIG AREA: Outra
AREA: Ciências Ambientais
SUMMARY:

The intercropping of cover crops with perennial crops, especially fruit crops, is already a consolidated agricultural practice and provides improvements in the physical, chemical and biological quality of the soil. However, in cocoa full-sun plantations, this practice still needs to be evaluated. Thus, the study was developed with the objective of evaluating the soil fertility and mineral nutrition of cacao carried in a full sun system and intercropped with cover crops. The experiment was carried at CEPLAC (Comissão Executiva do Plano da lavoura Cacaueira) in Ilhéus, BA. The study was carried in a 4x2 factorial scheme, in randomized blocks, with four treatments, referring to the use of cover crops (brachiaria, fabaceae, spontaneous plants and without cover), four replications and two years of evaluations. The experiment was implemented in July 2019 with a spacing of 1.5m x 4.0m, between plants and interrows, respectively, with cacao trees of the CEPEC 2002 clone. Initial shading with cassava was used, which was completely suppressed for the implementation of cover crops in March 2020. The cover crops were implanted in the interrows of the experimental area, in March 2020, and the treatment of Fabaceae, as it is an annual species, was replanted in 2021. For the other treatments, there was no need for replanting in 2021. In 2020, harrowing was carried out in all interrows of the system and the implantation of the cover crops, seeded by hand with manual incorporation. After the full development of cover crops, in the two years evaluated, the production of dry mass was determined and mowing was carried out. In December 2020 and 2021, soil sampling was carried out for chemical analysis in the 0-20 cm layer and sampling of cocoa leaves to evaluate the nutritional composition. In the soil pH was determined in water and CaCl₂, macronutrients (Ca²⁺, Mg²⁺, S, P and K+), micronutrients (Fe, Zn, Cu, Mn and B) and fertility parameters (Al³⁺, H+Al, SB, T, V, CTC, m and M.O). In the leaves it was determined: N, P, K, Ca, Mg, S, Fe, Zn, Cu, Mn and B. The cover crops produced high amount of dry mass, values considered adequate for the implementation of conservation systems. The consortium of Brachiaria with cocoa trees in a full sun system increased the levels of potassium in the soil approximately 3 times in relation to the initial levels of this element in the soil. In the two years of study, there was an increase in soil pH and boron micronutrient and a reduction in magnesium and iron. The use of cover crops in a full sun system decreased foliar nitrogen and zinc levels and increased potassium levels in the evaluated years. The treatments spontaneous vegetation, fabaceae and exposed soil, showed an increase in the levels of foliar phosphorus in relation to the treatment with brachiaria.

BANKING MEMBERS:
Presidente - 1126298 - JAQUELINE DALLA ROSA
Externo à Instituição - JÚLIO CÉSAR AZEVEDO NÓBREGA - UFRB
Externo à Instituição - ÁLVARO LUIZ MAFRA - UDESC