An Innovative Methodology for Groundwater Management with Reference to Saline Water Intrusion

The purpose of our study is to evaluate the impact of saltwater intrusion on the productivity and technical efficiency (TE) of rice farms in Central Vietnam using the stochastic frontier (SF) production function. In contrast to existing studies, this research quantitatively analyses rice variety and season-differentiated impact of soil salinity (as measured by electrical conductivity (EC)) on the TE of rice production. The empirical results indicate that salinity induces significantly varying negative impacts on yield and technical inefficiency of rice farms depending on the salinity class, variety planted and the season. TE begins to sharply decline after reaching salinity class 3 (EC = 4–8 dS/m) and drops to zero under salinity class 4 (EC = 8–16 dS/m) unless salt-tolerant (ST) varieties are planted. A 1% increase in the EC level decreases rice yields by 0.24% in various SF models, while TE shows a cubic relationship with EC, with negative coefficients for linear and quadratic terms. A combination of farm plots consolidation, irrigation, integrated pest management, input optimisation and shifts in varietal selection can potentially offset the yield decline caused by saline intrusion for salinity classes 1 to 4, while adoption of ST varieties seems to be the best option for higher salinity classes over 4. These adaptation measures could also help farmers to avoid maladaptive options such as increased use of pesticide sprays to offset the yield losses due to soil salinity resulting from saline water intrusion. The insights offered by the study is applicable to coastal delta regions cultivating rice in whole of Asia and in other continents.

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Available carbon and nitrate increase greenhouse gas emissions from soils affected by salinity

Soil Research ◽

10.1071/sr16010 ◽

2017 ◽

Vol 55 (1) ◽

pp. 47 ◽

Cited By ~ 5

Author(s):

Duy Minh Dang ◽

Ben Macdonald ◽

Sören Warneke ◽

Ian White

Keyword(s):

Carbon Cycling ◽

Soil Nitrogen ◽

Saline Water ◽

Alluvial Soil ◽

Acid Sulfate Soil ◽

N2o Production ◽

Saline Water Intrusion ◽

Acid Sulfate ◽

Water Intrusion ◽

Available Carbon

Sea-level rise and saline water intrusion have caused a shortage of fresh water and affected agricultural areas globally. Besides inundation, the salinity could alter soil nitrogen and carbon cycling in coastal soils. To examine the effect of salinity, an incubation experiment was used to investigate soil nitrogen and carbon cycling from an acid sulfate soil and an alluvial soil with and without additional nitrogen and carbon sources. Four levels of saline solution of 0.03, 10, 16 and 21dSm–1 were used to submerge acid sulfate and alluvial soil samples in a 125-mL jar. The experimental jars were incubated in the dark at 25°C. Gas samples were collected over 4 weeks and analysed for nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4). The results showed that salinity significantly decreased N2O emissions from the acid sulfate soil but did not affect emissions from the alluvial soil. Addition of glucose and nitrate enhanced N2O production in both salt-affected soils. Emissions of CO2 were not different among the salinity treatments, whereas available carbon and nitrate promoted soil respiration. Changes in CH4 fluxes over the 4-week incubation were the same for both soils, and substrate addition did not affect emissions in either soil. The findings indicate that salinity has altered carbon and nitrogen cycles in the acid sulfate soil, and future fertiliser and crop management will need to account for the changed nutrient cycling caused by saline water intrusion and climate change.

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