Acúmulo de nutrientes e produtividade de crambe em função da fertilização com torta de mamona e serpentinito.Ciência Rural, v.44, n.5, mai, 2014.
This work aimed to characterize the biochar produced from residues of coconut fruit and to evaluate how it might beneficially alter the retention capacity of water and nutrients in soils with a sandy texture. The biochar was produced in a retort furnace and later analyzed to determine its chemical and physical characteristics. Experiments to analyze the retention potential of the biochar for water and nutrients were performed in PVC columns filled to a 400 mm depth, with the upper 300 mm receiving treatments that consisted of 0, 1, 2, 3, 4, and 5% (p p-1) biochar mixed with soil. For the nutrient retention experiment, in addition to the biochar concentrations, the treatments received the same NPK fertilization. The experiments were performed in a completely randomized design with four replications. The water retention in the upper 300 mm, as well as the pH, effective cation exchange capacity (ECEC) of the substrate, base saturation, and concentrations of P and K, increased with increasing biochar concentration. Coconut biochar demonstrated potential for increasing water retention and improving nutrient retention in sandy soils.
-Studies have shown that some plant species exhibit satisfactory production levels when grown under high salinity levels, whereas others exhibit decreased production due to sodium sensitivity even at low sodium concentrations. The castor bean is moderately sensitive to salinity. The aim of the present study was to evaluate the early growth of three castor bean varieties (BRS Energia, MPA 34 and MPB 01) grown in nutrient solution with increasing sodium concentrations (control, 25, 50, 75 and 100 mmol L -1 ). A completely randomized split-plot experimental design was used, with a 5x3 factorial scheme and three replicates per treatment. Salinity resulted in decreased dry weight of all castor bean varieties grown for 31 days under hydroponic conditions. The dry weight accumulation was less affected at the root than at the shoot level. Nevertheless, the shoot dry weight decreased with the increasing salinity. MPA 34 exhibited higher early growth than the remaining tested varieties. Salinity affected the early development of the tested castor bean varieties, and this effect was more pronounced at the shoot than at the root. Variety MPA 34 is promising for cultivation under moderate salinity levels.Keywords: Ricinus communis. Sodium sensitivity. Osmotic adjustment. DESENVOLVIMENTO INICIAL DA MAMONEIRA EM CONDIÇÕES SALINAS (VARIEDADES BRS ENERGIA, MPA 34 e MPB 01)RESUMO -Pesquisas demonstram produções satisfatórias de espécies quando cultivadas em altos níveis de salinidade, enquanto outras reduzem a sua produção por apresentarem sensibilidade ao sódio, mesmo em baixas concentrações. A mamoneira é moderadamente sensível à salinidade e, neste sentido, este trabalho teve por objetivo avaliar o crescimento inicial de três cultivares de mamoneira (BRS Energia, MPA34 e MPB 01), cultivadas em solução nutritiva, com concentrações crescentes de sódio (controle; 25; 50; 75 e 100 mmol L-1). O delineamento experimental foi inteiramente casualizado, em fatorial 5x3 e parcela subdividida, com três repetições. A salinidade reduziu a matéria seca de todas as variedades de mamoneira cultivadas por 31 dias em sistema hidropônico. Entretanto, observou-se que o sistema radicular foi menos afetado quanto ao acúmulo de matéria seca, quando comparado ao acúmulo da parte aérea. Ainda assim, a matéria seca da parte aérea reduziu gradativamente a partir do aumento da salinidade. A variedade MPA 34 apresentou maior crescimento inicial, quando comparada as demais variedades. A salinidade afetou o desenvolvimento inicial das variedades de mamoneira, sendo a parte aérea mais afetada que o sistema radicular. O cultivo da variedade MPA 34 demonstrou-se promissor sob condições de moderados níveis de salinidade. Palavras-chave:Ricinus communis. Sensibilidade ao sódio. Ajustamento osmótico.
The use of agroindustrial wastes, such as vinasse, may alter the soil chemical and physical characteristics. This study aimed to evaluate the total organic carbon and total nitrogen in a soil and the distribution of carbon and nitrogen in the sand and clay granulometric fractions, in three management systems (with and without vinasse application and with burning for harvest, in comparison with primary/native forest coverage), regarding fertilization and harvesting of sugarcane, in the Midwest region of Brazil. The use of organic wastes in the sugarcane production system may promote, even in a short time frame, conservation and improvement of the soil quality by the addition and maintenance of organic carbon. The use of vinasse favors the increase of the total organic carbon and total nitrogen in the soil, in the clay fraction, at all evaluated depths. The system with burning results in lower total carbon levels in the sand fraction, in comparison with the clay fraction, and, even with the sugarcane harvest employing burning, the most recalcitrant organic matter is associated with the clay fraction.
Animal waste is widely used in organic production systems. However, these residues can increase antimicrobial determinants in the soil. In this perspective, this study was developed to evaluate the presence of sulfonamide resistance genes in soils from an organic production system that received animal waste as organic fertilizer. Soil samples were collected from four properties with different management practices to increase soil fertility. Three properties use the animal waste from the conventional system and the other use plant residues as soil cover and a legal reserve. The extraction of total DNA from soil was carried out followed by the amplification of genes encoding sulfonamide resistance (sul1 and sul2) by the PCR (polymerase chain reaction) technique. The sul1 and sul2 genes were detected only in soils treated with animal waste. The genes were not detected in soils from the legal reserve and the property that used plant residues as soil cover. These results indicate that the use of animal waste as agricultural fertilizer can increase genes for resistance to antimicrobials in the soil and the composting process may not be enough to eliminate them. This information reiterates the need to implement standards that establish quality parameters for animal waste, considering resistance to antimicrobials, as well as the development of management strategies that reduce the risk of spreading resistance to antimicrobials when these residues are applied to soils.
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