Banca de DEFESA: ANDRÉIA TEIXEIRA DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ANDRÉIA TEIXEIRA DA SILVA
DATE: 30/07/2024
TIME: 08:30
LOCAL: Sala de Aula da Pós-Graduaçao em Ciência Animal e Pastagens
TITLE:

Available Forms of Phosphorus and Management of Salinity in Salt-Affected Soils Cultivated with Forage Sorghum

KEY WORDS:

• Phosphorus fractionation,  Magnesium-induced salinity, Organic amendments

PAGES: 77
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SPECIALTY: Fertilidade do Solo e Adubação
SUMMARY:

The intensification of agriculture accelerates soil degradation, with the high concentration of soluble salts being one of the major global challenges affecting agricultural productivity. This study investigates the relationship between the fertility of saline soils for sorghum cultivation, focusing on two fronts: phosphorus (P) forms and salinity correction with magnesium (Mg). In the first experiment, the availability of phosphorus in Cambisols affected by salts collected in Serra Talhada, Pernambuco, was evaluated using a greenhouse experiment with increasing doses of phosphorus (0, 30, 60, 90, and 120 kg ha⁻¹ of P₂O₅) applied to soils cultivated with Sudan grass. After 50 days, the sorghum was harvested, and soil samples were collected to determine the available phosphorus using various extractors (Mehlich-1, Olsen, Chang & Jackson, Saunder, Soltanpour, and Pox) and chemical fractionation of inorganic phosphorus. The results of the phosphorus fractionation showed the absence of the labile fraction in all soils, as this is the fraction absorbed by the plant. The P fractions were influenced by soil characteristics such as pH, Ca, Na, and clay content, correlating with the P levels in the plants. In soil 1, the predominant fraction was stable calcium-P (54%), followed by residual P. In soils 2 and 3, residual P dominated, with 82% and 59%, respectively. In soil 4, non-labile iron-P was the most significant fraction, at around 53%. Principal component analysis revealed that the Fe and Al oxide-P fraction correlated with soil 2 (6.5%). Overall, the fractionation showed a predominance of P in the non-labile fractions, followed by less labile and labile fractions, with no significant correlation between the extracted P values and the availability to the plants. Even extractors recommended for alkaline soils, such as the Olsen extractor, proved ineffective. In the second experiment, salinity correction with Mg was evaluated in soils from regions with high Mg saturation. The soil was collected in Altinho (PE) and characterised as a Solodic Eutrophic Haplic Planosol. The treatments applied were: agricultural gypsum, dairy sludge, commercial humate, sludge + gypsum, humate + gypsum, biochar (chicken litter), and a control. Each repetition consisted of a 5 L pot with 7 Kg of soil, containing one sorghum plant, with 3 repetitions, divided into two cycles of 60 days each. Soil and plants were evaluated at 60 days of each cycle. Principal component analyses of plants and soils showed the relationship between the sludge and sludge + gypsum treatments. In the first cycle at 60 days, the Na+Mg saturation was lower in the treatments with dairy sludge (41.69%), gypsum (43.05%), and sludge + gypsum (43.90%) compared to the control (49.11%). In the second cycle, the sludge + gypsum (53.14%) and dairy sludge (53.32%) treatments maintained lower values for Na+Mg saturation. In cycle 1, the treatments with conditioners showed a higher amount of soluble sodium, significant reduction of exchangeable magnesium, and lower exchangeable sodium with the application of conditioners. At 120 days, electrical conductivity was significantly lower with conditioners, and there was a significant reduction in soluble sodium, soluble Mg, and exchangeable Mg. Soil conditioners significantly improved the morphological and physiological characteristics of sorghum plants, such as height, number of leaves, number of tillers, leaf width and length, and fresh and dry weight. There was a significant increase in the height of treated plants in both cycles. The length of the longest root  in cycle 1 and cycle 2, root dry weight , and root fresh weight were significantly greater in treated plants compared to the control in both cycles.

COMMITTEE MEMBERS:
Presidente - ALEXANDRE TAVARES DA ROCHA
Externa ao Programa - ***.352.124-** - MARIA CAMILA DE BARROS SILVA - UFRPE
Externa à Instituição - RAYANNE THALITA DE ALMEIDA SOUZA