Presentations 2016

ENVIRONMENTAL IMPACT OF SOIL MOISTURE MONITORING THROUGH CAPACITANCE PROBES OVER AQUIFER CONTAMINATION BY NITRATES

Instituto Nacional de Investigaciones Forestales, Agricolas y Pesqueras

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The pollution of aquifers by nitrates (NO3) is a major environmental problem. In Mexico there are few studies on NO3 levels in drinking water and the source of this contamination. If the content of nitrates (N-NO3) of 10 mg L¯¹ (NOM-127-SSA1-1994) is exceeded, it can be a health problem because nitrate intake can cause methemoglobinemia in infants and children, known as Baby Blue Syndrome (Comly, 1945; Magee and Barnes, 1956) syndrome and may be carcinogenic (Volkmer et al., 2005; Ward et al., 2005). Nitrate pollution of groundwater is related to the use of synthetic fertilizers or the existence of losses in septic systems. The objective was to evaluate the environmental impact exerted by the water management through micro sprinkler irrigation with optimized programming monitoring moisture capacitance probes FDR, compared with traditional management on pollution of aquifers by nitrates. This study was conducted during 2008 and 2009, in Cuauhtémoc, Chihuahua, in two apple (Malus domestica borkh) orchards: 1) Rosario orchard, with 570 hectares irrigated with 25 wells scheduled irrigation and FDR probes, 2) Macetas orchard (control), with 253 hectares irrigated with 13 traditional irrigation wells. In each orchard were installed 20 suction tubes with porous porcelain capsules to 150 cm deep. The leaching water was extracted at intervals equal to the moisture monitoring (weekly from March to September and monthly from October to February) analyzed the content of N-NO3 by colorimetric. Monthly N-NO3 content was analyzed in 38 wells. Water depths in 2008 was 948 mm in Rosario and 1720 mm. in Macetas, and rainfall 212 mm; in 2009 water depths in Rosario was 564 mm, and 1570 mm in Macetas, and rainfall 592 mm. In both orchards two fertilizations were applied with equal doses per year, in spring and autumn. The results showed that where irrigation water is optimized with FDR probes no significant effect on water depths applied over NO3 leaching. In orchard control there was a rise in the concentration of NO3 after deep irrigation, showing a highly significant effect, which shows that if water depths exceed the water needs of the crop, NO3 leached in depth washed away through the unsaturated zone soil (ZNS) contaminating aquifers.