Transport parameters of potassium from different sources in soil columns

This study aimed to determine some transport parameters of potassium in soil columns by miscible displacement of effluent from a Sewage Treatment Plant (STP). This effluent was collected at different stages of treatment, and potassium chloride solutions were prepared with the same K pulse concentration as the effluent. They were used to conduct a miscible displacement experiment of potassium in soil columns of dystrophic Red Latosol. Both types of solutions contained concentrations of 30 and 32 mg L-1 of potassium. STANMOD software was used to obtain the retardation factor (R) and the Peclet number (Pe) from pore volume and relative concentration. Both retardation factor and solid-water partition coefficient of the soil showed significant results by ANOVA. When assessing KCl solutions, retardation factor was higher than that observed for the effluent, resulting in higher soil-solute interaction. The presence of other competitor cations in the effluent caused less potassium adsorption by the soil. Based on the results, potassium provided a greater groundwater pollutant potential when applied via effluent than solutions of potassium chloride with the same ion concentrations

CONCENTRAÇÃO DE NUTRIENTES NA ÁGUA DE DUAS LAGOAS URBANAS DO MUNICÍPIO DE FORMIGA / NUTRIENTS CONCENTRATION ON THE WATER OF TWO URBAN LAGOONS FO FORMIGA CITY - MG

A água é o recurso natural mais importante da Terra, sendo indispensável para a vida, assim, sua qualidade deve ser preservada. Este trabalho tem por objetivo analisar a concentração de nutrientes nas Lagoas do Fundão e do Josino, ambas localizadas no município de Formiga, no Estado de Minas Gerias. Para tal, foram coletadas amostras de água em diversos pontos das Lagoas, que apresentam diferentes formas de uso e ocupação em suas imediações. Entre os meses de agosto de 2015 a fevereiro de 2017 foram analisados os seguintes parâmetros: pH, nitrato, nitrito, íon amônio, potássio e fósforo, todos em vinte repetições. Os resultados obtidos para fósforo total não estão de acordo com o preconizado pela Resolução 357/2005 do CONAMA para Corpos Hídricos Classe 1, para ambas as Lagoas, caracterizando suas águas como eutrofizadas

Rendimento da pimenta cayenne em função de diferentes tensões de água no solo

Objetivou-se, neste trabalho, avaliar as tensões de água no solo em duas fases fenológicas (vegetativa e reprodutiva) da cultura da pimenta Cayenne, cultivada em ambiente protegido e irrigada por gotejamento. Foram instalados dois experimentos utilizando-se um delineamento inteiramente casualizado cujos tratamentos foram definidos por quatro tensões de água no solo (20, 40, 60 e 120 kPa) e quatro repetições. Os maiores valores de massa média de frutos por planta foram obtidos para a tensão de 20 kPa, sendo 1936,83 e 2091,59 g por planta e os coeficientes de rendimento obtidos foram 0,81 e 1,01, para as fases vegetativa e reprodutiva, respectivamente. Com base nos resultados apresentados concluiu-se que: a produtividade da cultura apresentou comportamento inversamente proporcional à tensão de água no solo e a tensão de 20 kPa mostrou-se mais adequada para promover as irrigações nas fases estudadas. Os coeficientes de rendimento identificaram a fase reprodutiva como a mais sensível ao deficit hídrico

EFFICIENCY ANALYSIS OF A WATER RESERVOIR ALTERNATIVE LINING / ANÁLISE DE EFICIÊNCIA DE REVESTIMENTO ALTERNATIVO PARA RESERVATÓRIO DE ÁGUA

Cost of lining reservoirs, whether for storage or water treatment, can be made it with different materials. As these structures have a relatively large surface area the investment amount can be economically unfeasible. A sustainable alternative method that can be used is the reduction of water infiltration in the soil, carried out through the use of a chemical dispersant such as Sodium Hydroxide (NaOH). Therefore, the aim of the present research was to define the lower NaOH concentration and volume to be applied in samples of a Red Latosol in the southern region of Minas Gerais state, Brazil. The samples, in triplicate, were treated with 5 NaOH concentrations (0, 5, 10, 15 and 30 g L-1) and 3 volumes per square meter application (5, 15 and 25 L m-2), submitting it to saturated hydraulic conductivity in constant head permeameters tests. The results showed that the application of different concentrations of NaOH reduced the saturated hydraulic conductivity in relation to the control treatment. The ratio of condutivity to NaOH concentration is best represented by the cubic regression y = 22.46 - 6.06x + 0.45x² - 0.01x³ (r² = 0.97). Regarding the different application rates, the difference was not significant indicating equality between the treatments analyzed. Therefore, the use of the 5 g L-1 of NaOH, applied at 5 L m-2, was economically more feasible and could therefore be a low-cost lining alternative.</p

Microbiological properties in cropping systems and their relationship with water erosion in the Brazilian Cerrado.

Many researchers have reported relationships of physical and chemical properties with water erosion; however, little is known about microbiological properties in this context. Thus, the aim of this study was to evaluate soil properties in relation to erosion in areas with different cropping system practices under no-tillage in the Brazilian Cerrado. The experiment has been carried out since 2014 in a Typic Haplustox under soybean (S) and maize (M) monoculture, maize/soybean annual rotation (MS), maize/brachiaria/soybean/brachiaria rotation (MBSB), two of those treatments with high input of fertilizer (MBSB-HI and MS-HI), and bare soil (BS). Soil losses were quantified in erosion plots. The design was completely randomized. The greater vegetation cover crop, provided by intercropping/succession with brachiaria, increased microbial biomass carbon. The lack of vegetation cover affected the basal soil respiration and metabolic quotient. Basal soil respiration proved to be inversely related to soil and water losses. Vegetation cover was a key factor regulating water erosion. Penetration resistance and aggregate stability correlated with soil and water losses. Thus, not only physical and chemical, but also biological properties are deeply affected by erosion, aiding in early monitoring of water erosion. Soil quality improvement in ecologically supported management contributes to mitigating erosion

Economic analysis of irrigated melon cultivated in greenhouse with and without soil plastic mulching

ABSTRACT The objective of this study was to analyze technically and economically the irrigated ‘Gália’ melon (Hybrid Nectar), cultivated in greenhouse with and without using plastic mulch covering on the soil. Simultaneously, two experiments were conducted using a completely randomized design (CRD), in which melon plants were submitted to five water availability levels, defined by 50, 75, 100, 125, and 150% of crop evapotranspiration, with four replicates. The difference between experiments were only about the soil covering with plastic mulch: with (CC) or without (SC) plastic mulch. The economically optimal irrigation depths were 208.83 and 186.88 mm, resulting in yields of 50.85 and 44.51 t ha-1 for the experiments with and without mulching, respectively. The results showing the economically optimal irrigation depths were very close to those that produced the highest yield