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| Author(s): |
João Leonardo Corte Baptistella
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2020-01-23 |
| Examining board members: |
Paulo Mazzafera;
Sara Adrián López de Andrade;
Paulo Sergio Pavinato
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| Advisor: | Paulo Mazzafera |
| Abstract | |
Coffee cultivation in Brazil is made under full sun exposure on bare soil. This favors stress on the coffee tree, mainly due to high soil temperatures and water deficit. Among the ways to alleviate these negative effects is the adoption of the coffee-brachiaria intercrop. This intercrop system promotes several benefits, such as solubilization and cycling of nutrients such as phosphorus (P), to name a few. In this system, the brachiaria that grows between coffee lines is mowed and its residues deposited close to the coffee tree. Because the forage has a root system that exploits a large volume of soil, the brachiaria would be able to absorb nutrients that are unattainable to the coffee roots, making them available after decomposition and increasing nutrient cycling. Although important, from the point of view of efficient use of resources, there is little information about P cycling in this intercrop. The objective of this work was to study P cycling by the brachiaria intercropped with coffee and to compare brachiaria species regarding P acquisition and use. Three essays were assembled: (I) on field, (II) on rhizotron and (III) hydroponics. On essay I, P was applied on three soil depths (30, 60 and 90 cm) under brachiaria decumbens (Urochloa decumbens) intercropped with coffee; in essay II, we applied P up to 2 m on rhizotron cultivated with brachiaria decumbens. On both essays the objective was to verify P cycling from deep soil layers by brachiaria, for this reason, root and shoot biomass, soil P fractioning and nutrient accumulation in the shoot were evaluated. In essay III, 3 brachiaria species - decumbens, brizantha (Urochloa brizantha) and ruziziensis (Urochloa ruziziensis) - were cultivated on nutrient solution containing 4 levels of P availability - 0.2, 0.5, 1 e 2 µM.L-1. The objective, in this case, was to compare species on their capacity to acquire P, therefore, biomass production, acid phosphatase activity and organic acid root exudation were accessed. Taken together the three essays showed that the magnitude of P cycling depends on shoot biomass production and has a high positive correlation (r > 0.9) with P availability up to 80 cm of depth. Although the forage was efficient to use and absorb P, we found no effect of mobilization of the more recalcitrant P fractions on field conditions nor rhizotron, the duration of the experiment might have been not enough to access these changes. The results of the hydroponics suggest that there are differences between brachiaria species in P use efficiency and growth according to P availability, brachiaria ruziziensis being the one presenting the best results. Therefore, depending on the system fertility and management, the species of brachiaria that will achieve better results may differ. (AU) | |
| FAPESP's process: | 18/02497-3 - Phosphorus cycling by palisade grass intercropped with coffee tree |
| Grantee: | João Leonardo Corte Baptistella |
| Support Opportunities: | Scholarships in Brazil - Master |