Due to unavoidable, prolonged irrigation with marginal quality water, secondary salinization of irrigated soils in Pakistan has necessitated to a need for better understanding of the water management alternatives. Although H2SO4 and gypsum have far been recognized for their benefits in treating brackish water but during field trials, their relative performance still remains controversial for counteracting the Na-hazards in soil/water system. As alternative sulfur burners are also being marketed but up till now there is not even a single field study published in some journal about their efficiency and economical viability for the treatment of brackish water. Therefore a field study was carried out to compare the effectiveness of sulfurous acid generator (SAG) and other water/soil applied amendments on a normal, calcareous, well drained, sandy loam soil. Rice 2001, wheat 2001-02, and rice 2002 were planted in rotation during the experimentation period with a total of 54 treated and 8 untreated irrigations (each of 7.5 cm). Tube well water used had EC = 3.24 dS m-1, SAR=17.23 and RSC = 5.44 mmolc L-1. The treatments were: T0) Brackish tube well water without any amendment; T1) All irrigation with water passed through SAG; T2) Alternate irrigation-one of SAG treated and one of tube well water, T3) One irrigation with SAG treated water and two with untreated tube well water; T4) FYM @ 15 t ha-1yr-1; T5) Soil applied gypsum to each crop equivalent to affect a decrease in WRSC of tube well water treated with SAG, and T6) H2SO4- fertigation at each irrigation equivalent to affect a decrease in RSC of tube well water with SAG. Water analysis after treatment with SAG (an average of 20 irrigations) revealed that SAG treatment affected only one parameter i.e. water RSC from 5.44 to 3.55, and had no beneficial effect on SARiw and ECiw. After three crops, a minor decrease (up to 2.5%) and increase (up to 5.3%) in soil pHs over initial values was noted at 0-15 & 15-30 cm depth. After three crops the soil ECe and SAR were maintained below the threshold levels and the treatments had non-significant differences. On the basis of three crops, net benefit was maximum, from T4 followed by T5, T3, T0, T2, T6 and T1. The use of sulfur burner/ sulfuric acid was found to be 5 times costlier than gypsum in our study. It is concluded that soil application of gypsum and/or farmyard manure to counter the sodic hazards of irrigation water will be useful as well as economical for rice-wheat rotation on a normal, calcareous well drained soil. However, for fine textured soils with low infiltration rates, to expect similar situation might not be correct for which additional studies are imperative.

To evaluate the base line levels of potentially toxic and essential trace metals namely, Cd, Ph, Cr, Mn, Ni, Cu and Zn in water, locally grown vegetables, cereals and vegetable ghee-oil samples of a highly industrial city Gujranwala have been measured after wet digestion by employing AAS technique. Sampling was made from selected sites in and around the city over a period of three months. The concentration of Mn, Ni, Zn, Cu and Pb was found significantly higher in vegetables ranging from 3-63, 2-81, 5-92, 7- 70 and 6-60 ppm respectively. Nickel and Cu concentration was found higher in cereals whereas, Cd was found at ppb level in all variety of samples studied. Tap water, vegetable ghee-oil have recorded lower concentration of these metals. Vegetables collected from urban area have shown elevated level of contamination than those of taken from canal irrigated farms. The overall level of trace metals with few exceptions of vegetable samples was found within the permissible limits fixed by WHO. The analytical method was checked by applying on SRM of wheat and spinach. The results were found in agreement with the certified values within experimental error. The major polluting sources of the city such as automobile, man made activities, soil and road dust, metallic corrosion and industrial activities have been indicated. The environmental impacts of pollutants on water and food quality of an industrial and non-industrial city are briefly discussed in the light of their adverse effects on human health.

Steam injection heating systems for food and agricultural products are subject to condensation-induced water hammer (CWH), which may cause significant damage to equipment and pose a threat to operators. A method is suggested for process design and operation of a steam injection heater that reduces occurrence of CWH. The method is based on a correlation between the thermodynamic ratio of the product and the Peclet number. A laboratory steam injection heater was instrumented to determine the relationship between CWH, the thermodynamic ratio, and the Peclet number. The thermodynamic ratio for water and various concentrations (55 to 67.5 brix) of sucrose solution was recorded under process conditions at the onset of CWH during steam injection heating. Good correlation was observed between the Peclet number and threshold thermodynamic ratio. A linear equation was found (with r 2 = 0.79) that gives the predicted minimum thermodynamic ratio for system operation without CWH.

This report derives from the importance of water for irrigation to the question, how will additional food be produced as competition for scarce land and water resources increases? The International Water Management Institute (IWMI), Food and Agriculture Organization of the United Nations (FAO), and International Food Policy Research Institute (IFPRI) provide a partial picture of supply and demand for food supply and irrigation-water by 2025 and 2030. The World Bank initiated a validation exercise in cooperation with these agencies to ensure that the models: consider a balanced range of assumptions and scenarios; introduce additional assumptions and scenarios; and replace, or fine-tune, some of them. It attempts to introduce into the forecasts the possible impacts of additional policy interventions and to evaluate their likely effects on the global projections of agriculture-water supply and demand. The validation exercise provides a review of the existing model structure and components, the assumptions made, the scenarios, and scenario results. Model assumptions, scenarios, and results of the revised response from the IWMI, FAO, and IFPRI are given as a part of the validation exercise as well as assumptions made and scenarios developed under different criteria and issues as raised by the group of experts.

This report derives from the importance of water for irrigation to the question, how will additional food be produced as competition for scarce land and water resources increases? The International Water Management Institute (IWMI), Food and Agriculture Organization of the United Nations (FAO), and International Food Policy Research Institute (IFPRI) provide a partial picture of supply and demand for food supply and irrigation-water by 2025 and 2030. The World Bank initiated a validation exercise in cooperation with these agencies to ensure that the models: consider a balanced range of assumptions and scenarios; introduce additional assumptions and scenarios; and replace, or fine-tune, some of them. It attempts to introduce into the forecasts the possible impacts of additional policy interventions and to evaluate their likely effects on the global projections of agriculture-water supply and demand. The validation exercise provides a review of the existing model structure and components, the assumptions made, the scenarios, and scenario results. Model assumptions, scenarios, and results of the revised response from the IWMI, FAO, and IFPRI are given as a part of the validation exercise as well as assumptions made and scenarios developed under different criteria and issues as raised by the group of experts.