Evaluation of the impacts of uncontrolled agricultural practices on soil and water resources on the Al-Far’a catchment

Most of the agricultural land and ground water in Al-Far’a catchment are being excessively used with the absence of proper management. Uncontrolled agricultural practices could cause pollution through the release of several pollutants, such as agrochemicals (pesticides and fertilizers), manures, and heavy metals into receiving waters, soils and crops. In order to assess and evaluate the impacts of uncontrolled agricultural practices on groundwater, soil and crops in Al-Far’a catchment. Water samples from 33 different agricultural wells were collected and analyzed to detect the presence of nitrates (NO3-), phosphate (PO4-3), COD, BOD, electrical conductivity (EC), hardness, total dissolve solid (TDS) and pH. At the same time, Soil samples at three depths (0-20, 20-50, 50-100 cm) and crops samples (leaves, shoots and fruits) were collected from different areas in the catchment to analyze the accumulation of nitrate, phosphate, heavy metals (Fe, Cu, Zn, Cd, Pb and Ni) and lufenuron and abamectine pesticides residues. Field questionnaire was prepared and distributed to gather data from 155 farmers in different places in the catchment. The data was used to investigate and characterize the agricultural activities that were practiced by farmers in the catchment. The results showed that one out of 33 wells contained nitrate level that exceeded the WHO standards for drinking water. One well contained phosphate level that exceeded the EU standards for drinking water and the FAO standards for irrigation water. The water in the wells was very hard, while the levels of TDS, EC and pH in the wells were found within the permissible limit of the WHO standards for drinking water and the FAO standards for irrigation water. The level of COD in two wells and BOD level in eight wells were higher than the allowed concentration for irrigation water quality. The results showed that the level of phosphate on soil samples were higher than the recommended environmental level of phosphate soil content and crops need, the highest level of phosphate was detected at the top soil. Soil was polluted by nitrate and the highest nitrate level was detected at 20-50 cm depth. Heavy metals levels were lower than the maximum allowable limit of the WHO standards. The order of heavy metals level in soil was Fe > Zn > Ni > Cu > Pb > Cd. Although heavy metals levels in soil were within the permissible limit, however the ongoing agricultural practices could lead to increased accumulation of heavy metals in soil. Analysis showed considerable residues of lufenuron and abamectine pesticides in soil and the highest level was at top soil. The nitrogen level in cucumber and aubergine was found within permissible the WHO standards. Phosphate and nitrate concentrations recorded higher levels in leaves than other parts of both crops. Cucumber showed more ability to accumulate nitrogen and phosphate than aubergine. The order of Heavy metals levels in the two crops was Fe> Zn> Cu>Ni >Pb > Cd. Noting that the accumulation of heavy metals in cucumber were higher than its accumulation on aubergine. In both crops, Ni and Cu levels were below permissible the WHO standards. It was noticed that Cd and Pb levels (in all parts of the two crops), Fe level (in leaves and shoots of the two crops) and Zn level (in aubergine shoot) were found higher than the maximum allowable limit of the WHO/FAO standards. Lufenuron pesticide residues in green bean were found at levels above the permissible limit of the EU standards and the level of abamectin pesticides residues in aubergine was higher than the permissible limit of the WHO/FAO standards. The results of field questionnaire revealed that the average level of knowledge and perception of the respondents about agrochemicals is moderate. Most of the Al-Far’a farmers have finished secondary school and part of them have university degree, this enables them to accommodate new technologies in plant protection. Most of the farmers try to take some measures to prevent wells pollutions. Most of the Al-Far’a farmers do not receive any training to deal with pesticides and do not have the enough knowledge about the modern techniques and alternatives for using pesticides. Al-Far’a farmers consider pesticides as the best solution for them.