Abstract
Agriculture is the major user of water resources, accounting for 70% of global freshwater demand. As the demand for clean water increases, so does the need to implement more efficient strategies for water management in irrigated agriculture. While the benefits of precision irrigation in high-value crops, such as cannabis, tomatoes, and potatoes, are fully recognized, there is still need to investigate and implement cheap and efficient irrigation strategies for widespread low-value crops such as maize. In this study, the soil moisture dynamics in a sprinkler-irrigated maize field in Veneto (Northeastern Italy) was monitored using six time domain reflectometry (TDR) probes for the entire growing season. The TDR sensors were positioned at different depths into two separate sites: an Uninformed Site irrigated based on the farmer's experience and an Informed Site in which a water balance irrigation strategy was applied based on soil moisture measurements. A parsimonious hydrological model was then implemented and calibrated to quantify the different water balance terms (precipitation, evapotranspiration, lateral fluxes, and deep percolation). The comparison between the water budget terms in the two sites highlights that soil moisture monitoring during agriculture activities leads to substantial savings in terms of irrigation water volumes requirements and cost, without compromising the productivity of the crop field. A simplified upscaling of the results at the regional scale, assuming average conditions as in this study site and growing season, reveals that potentially significant economic savings, compared to the total profits linked to maize crops, could be possible.
Highlights
Agriculture accounts for around 70% of global freshwater withdrawals, reaching up to 90% in some fast-growing economies, irrigation and food production representing one of the major uses of freshwater resources, with about 3,100 km3 of annual water consumption (World Water Assessment Programme, 2012)
About 40% of the total food production is relying on irrigated agriculture, which represents less than 20% of the total cultivated lands (World Water Assessment Programme, 2009), while global population growth projections of 2–3 billion people over the 40 years, combined with changing diets, are estimated to result in a food demand increase of 70% by 2050 (World Water Assessment Programme, 2012)
Soil moisture in a maize field in the Veneto region (Northeastern Italy) was continuously monitored during the 2013 growing season by six time domain reflectometry (TDR) probes installed at two different locations and three different depths
Summary
Agriculture accounts for around 70% of global freshwater withdrawals, reaching up to 90% in some fast-growing economies, irrigation and food production representing one of the major uses of freshwater resources, with about 3,100 km of annual water consumption (World Water Assessment Programme, 2012). Water resources management largely depends on climatic and soil factors as well as freshwater availability, with rainfall representing the primary source of uncertainty in quantifying the productivity and profitability of crop fields (Vico and Porporato, 2011). Micro-irrigation is one of the newest and most efficient irrigation schemes for water use optimization, but its installation and maintenance cost is very high compared to surface and sprinkler irrigation schemes. The latter are the most diffuse worldwide and balance sustainability, yield and profitability with lower cost for farmers (Vico and Porporato, 2011)
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