Resíduos de azevém na superfície de um Planossolo alagado e seus efeitos na concentração de nutrientes na solução do solo e em plantas de arroz

Abstract

IIIResíduos de azevém na superfície de um Planossolo alagado e seus efeitos na concentração de nutrientes na solução do solo e em plantas de arroz (0,0; 1,25; 2,5; 5,0; 7,5 ABSTRACT The incorporation of ryegrass residues on the soil in rice irrigated fields can improve the physical, chemical and biological soil properties. It can also accelerate the redox reaction during the soil flooding, allowing a higher availability of nutrients to the plants, which responds with a higher growing and nutrient absorptions. The objectives of this research are to quantify the nutrient absorptions, the rice crop growing, and to determine the concentration of nutrients in the soil solution on a flooding Albaqualf soil. For this, increasing doses of ryegrassresidues were applied in the soil surface. A greenhouse experiment was carried out using a randomized complete block design with six doses of ryegrass residues (0.0; 1.25; 2.5; 5.0;

Eletrochemical changes in Gleysol of the Amazon estuary

“…The available Mn in the soil increased with waterlogging and ranged from 245 to the maximum of 437 mg kg -1 on the 39 th day of flooding and declined thereafter to values of 294 mg kg -1 at the end of the experiment (Figure 4b). The maximum contents of Mn in samples of a Haplic Planosol collected in the city of Capão do Leão were observed at 44 days of waterlogging (Schmidt et al, 2009). Increases in the content of Fe and Mn were also found by Gonçalves et al (2011) in samples of different soils that were used for irrigated rice cultivation in Rio Grande do Sul and waterlogged for 45 days.…”

“…These authors found that after the 31 st day, the pH values stabilized between 7.1 and 7.2. In Haplic Planosol samples from Capão do Leão, Rio Grande do Sul, Brazil, the pH increased to 6.2 after 15 days of waterlogging (Schmidt et al, 2009).…”

“…A sharp decline in Eh in Haplic Planosol samples from Capão do Leão subjected to waterlogging was reported by Schmidt et al (2009) and explained by the intensification of redox soil processes. Redox processes occur because of the release of substances reduced in the system, with subsequent decreases of the partial oxygen pressure before compounds such as Mn and Fe oxides and hydroxides can exercise their buffering capacity and maintain Eh at intermediate values (Ponnamperuma, 1972).…”

Uptake and exportation of micronutrients in high productivity corn fields

“…These authors, in a nutrient exclusion study, observed that in treatments with high pH this micronutrient was not available to the plants, and Mn leaf contents were small regardless of the application. On the other hand, a high accumulation of Fe in the aerial partscan also cause decrease in the absorption not only of the Mn, but also of other divalent cations, such as Zn and Cu (SCHMIDT et al, 2009).…”

“…Esses autores, em estudo com omissão de nutrientes, observaram que nos tratamentos em que o pH foi elevado esse micronutriente não foi disponibilizado para as plantas, e os teores nas folhas foram menores independentemente da aplicação. Por outro lado, o maior acúmulo de Fe na parte aérea, também, pode causar diminuição na absorção não só do Mn, mas também de outros cátions divalentes, como Zn e Cu (SCHMIDT et al, 2009). O valor médio acumulado de Fe na planta inteira, 9.714 g ha -1 (Tabela 3), foi maior que o encontrado por Faria (2014), de 4.640 g ha -1 , e por Duarte et al (2003), de 5.650 g ha -1 .…”