Md. Shariot-Ullah*
Department of Irrigation and Water Management, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh
Md. Touhidul Islam
Department of Irrigation and Water Management, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh
Khalid Mahmud
Department of Irrigation and Water Management, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh
Wastewater; Irrigation; Sugar mills; Soil; Chemical properties; Solute-transport properties
Crop-Soil-Water Management
Water management, Waste water, Fertilizer
The main purpose of the experiment was to evaluate the soil chemical and solute-transport properties to observe the effect of sugar mill's wastewater irrigation on irrigated soil. Irrigation treatments applied on wheat field. Wastewater has both positive and negative effect on crop by changing different soil properties. The chemical and solute-transport properties were measured in the laboratory to investigate the suitability of soil chemical and solute-transport properties for the specific crop wheat. The soil type of the area is silty loam. Soil samples were collected from irrigated wheat fields (under investigation) of the sites after harvesting of the crop at 20 cm increments to a depth of 60 cm. Wheat was cultivated at two different sugar mill sites - North Bengal Sugar Mill (NBSM) and Faridpur Sugar Mill (FSM) sites under different irrigation and fertilizer levels. The experiments were set in a split-plot design with three replications of the two factors (irrigation and fertilizer). Irrigation was applied in main plots and fertilizer was distributed in subplots. The plot size was 3 m × 2 m.
Irrigation had three treatments: I1 = irrigation with fresh water, I2 = irrigation with mixed water (fresh water: wastewater = 1:1) and I 3 = irrigation with wastewater.
Fertilizer also had three treatments: F 1 = Full dose fertilizer, F 2 = Half dose fertilizer and F 3 = No application of fertilizer
After soil collection and sample preparation, different properties of soil mainly the chemical and solutetransport properties were measured. Soil samples were chemically analyzed for pH; EC; organic-C; total-N; available P and S; exchangeable K, Na, Ca and Mg. The EC and pH of the soils were determined at soil to solution ratio of 1:2.5 in an aqueous suspension of soil using a combine electrical conductivity and pH meter. For this measurement, 20 g of each air-dried soil was taken into separate conical flasks of 100 ml capacity, and 50 ml distilled water was added with each soil. The soil-water mixture was shaken by using a shaker at 200 rpm for 10 min. Then, the conical flasks were kept undisturbed for 10 min and shaken again at the same rpm and for the same time. The soil-water mixtures, called the saturation paste, were kept undisturbed in a control room for 5 h to attain equilibrium at 250C. The saturation extract was separated from the saturation paste carefully. The EC and pH of the saturation extracts were measured by the combined conductivity and pH meter. Other chemical properties of the soil samples were determined in the Soil Analytical Laboratory of Bangladesh Rural Advancement Committee (BRAC), Gazipur. A few parameters were analyzed in the Humboldt Soil Testing Laboratory of the Department of Soil Science, Bangladesh Agricultural University, Mymensingh. A breakthrough experiment was done to determine the impacts of irrigation with sugar mills’ wastewater on the solute-transport properties of soil. A constant rate of water flow through the soil columns was established by using a peristaltic pump before starting an experiment. Water was spread uniformly over the surface of the soil using a thick layer of absorbing cloth. The surface of the soil in the upper columns and the annular surfaces of soils in the lower columns were covered with a PVC sheet to prevent evaporation. The whole system reached equilibrium with the applied and drainage water in two weeks. The equilibrium condition was confirmed from the identical rates of the soil-water content measured by TDR. At equilibrium, a pulse of CaCl2 solution (2 g CaCl2 mixing with 3 ml water) was applied on the surface of each soil columns. The applied solution dispersed and moved through the soil profile with the moving water. The datalogger was programmed to scan the TDR sensors for measuring the volumetric water content and EC at the pre-selected time intervals (usually 1 hour). These measurements were continued until the whole of the applied salt was leached out from the upper columns. A breakthrough curve (BTC) is the plot of concentration or its equivalent quantity versus time. By analyzing a BTC, the transport parameters of a solute are determined. There are several methods for analyzing BTCs. Transfer-function (Mojidet al., 2004) is a well-accepted method for this and was used in this study. The following solute-transport parameters were determined:
V = velocity of solute, cm/h τ = travel time of solute, h Nd = mass dispersion number D = dispersion coefficient, cm2 /h R = solute retardation factor P = Peclet number λ = dispersivity, cm
The obtained data from the experiment has been analyzed statistically by using Mstat-C to assess the significant effects and the variation in the results. The measured data was accumulated based on field and lab research. So the quality of information is authentic and unique in nature.
Asian Australas. J. Biosci. Biotechnol. 2016, 1 (3), 521-532 ISSN 2414-1283 (Print) 2414-6293 (Online)
Journal