Banca de DEFESA: LUANA DO NASCIMENTO SILVA BARBOSA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : LUANA DO NASCIMENTO SILVA BARBOSA
DATE: 26/02/2024
TIME: 09:00
LOCAL: Campus Arapiraca
TITLE:

COVER CROPS UNDER PHOSPHATE SOURCES AFFECT P DYNAMICS AND SOIL MULTIFUNCTIONALITY IN SHORT-TERM CONSERVATION MANAGEMENT

KEY WORDS:

P fractionation; efficient P-use; enzymatic activity; soil biology, crops diversity.

PAGES: 69
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SPECIALTY: Fertilidade do Solo e Adubação
SUMMARY:

Phosphorus (P) is a limiting nutrient in tropical soils, and effective phosphorus fertilization management is essential to reach critical levels for agricultural crops, despite its low efficiency in P use. The adoption of cover crops can enhance P recycling, thereby altering soil P dynamics and optimizing phosphate fertilizer efficiency. These benefits may be associated with microbial activation and soil multifunctionality. The overall objective was to determine changes in P dynamics and soil microbiota promoted by cover crops and P sources in the short term in Alagoas. The study was conducted on sandy soil over two corn crops under no-till. The treatments included two P sources (single superphosphate (SSP) and rock phosphate (RP)) and a control without P addition (Nil-P), associated with six summer cover crop species and a fallow. Chemical P fractionation, P extraction by cover crops, and corn P export were determined in both crops. Enzymes for C, N, and P-acquisition by microbiota, microbial biomass, labile C, and total soil C and N were determined only after the second crop to estimate soil multifunctionality. In the first crop, cover crops altered P dynamics, increasing ~38% compared to fallow in the labile P pool where no P was added in the 0-10 cm depth, especially with spectabilis, pigeon pea, sunn hemp, and millet. However, in the second crop, they depleted this P fraction. Where P sources were applied, the labile and moderately labile P pools increased substantially, mainly associated with millet in the 0-5 cm depth. Between crops, cover crops depleted non-labile P from the 10-20 cm and accumulated it in the initial depth (0-5 cm). Under SSP, there was an increase in P use efficiency with lab lab, spectabilis, sunn hemp, and pigeon pea compared to fallow. Similar responses occurred under RP, except with spectabilis. Cover crops modulated enzymatic activities for C, N, and P-acquisition. P-acquisition was superior under RP, especially with lab lab. Similar results with lab lab were observed for C and N-acquisition, with higher responses in the initial depth (0-5 cm), although N-acquisition was higher in Nil-P but did not differ from fallow. P addition favored microbial biomass, regardless of the depth. In No-P, similar levels occurred only in the 0-5 cm, with significant losses in the 5-10 cm. Overall, only sunn hemp and millet did not differ from fallow. Regarding soil multifunctionality, fallow was negative regardless of P sources, and the best responses occurred with jack bean and spectabilis. Thus, cover crops modulated soil P fractions due to nutrient cycling within the agricultural system (micro-soil-plant), improving phosphate fertilization efficiency and activating soil multifunctionality.

COMMITTEE MEMBERS:
Presidente - 2626313 - VALDEVAN ROSENDO DOS SANTOS
Interno(a) - 1506475 - ALYSSON WAGNER FERNANDES DUARTE
Externo(a) ao Programa - 1120948 - GILSON MOURA FILHO - UFALExterno(a) à Instituição - DAYANE MERCIA RIBEIRO SILVA - UNESP
Externo(a) à Instituição - RICARDO BARROS SILVA - UFAL