Integrating High Resolution Water Footprint and GIS for Promoting Water Efficiency in the Agricultural Sector: A Case Study of Plantation Crops in the Jordan Valley.

Addressing the global challenges to water security requires a better understanding of humanity's use of water, especially the agricultural sector that accounts for 70% of global withdrawals. This study combined high resolution-data with a GIS system to analyze the impact of agricultural practices, crop type, and spatial factors such as drainage basins, climate, and soil type on the Water Footprint (WF) of agricultural crops. The area of the study, the northern Lower Jordan Valley, covers 1121 ha in which three main plantation crops are grown: banana (cultivated in open-fields or net-houses), avocado and palm-dates. High-resolution data sources included GIS layers of the cultivated crops and a drainage pipe-system installed in the study area; meteorological data (2000-2013); and crop parameters (yield and irrigation recommendations). First, the study compared the WF of the different crops on the basis of yield and energy produced as well as a comparison to global values and local irrigation recommendations. The results showed that net-house banana has the lowest WF based on all different criteria. However, while palm-dates showed the highest WF for the yield criteria, it had the second lowest WF for energy produced, emphasizing the importance of using multiple parameters for low and high yield crop comparisons. Next, the regional WF of each drainage basin in the study area was calculated, demonstrating the strong influence of the Gray WF, an indication of the amount of freshwater required for pollution assimilation. Finally, the benefits of integrating GIS and WF were demonstrated by computing the effect of adopting net-house cultivation throughout the area of study with a result a reduction of 1.3 MCM irrigation water per year. Integrating the WF methodology and local high-resolution data using GIS can therefore promote and help quantify the benefits of adopting site-appropriate crops and agricultural practices that lower the WF by increasing yield, reducing water consumption, and minimizing negative environmental impacts.

Fate of soil-applied olive mill wastewater and potential phytotoxicity assessed by two bioassay methods.

Controlled land spreading of untreated olive mill wastewater (OMW) has been widely practiced as a means of its disposal. However, potential phytotoxic effects are critical for the selection of sites and crop types and for proper synchronization between land application and cropping. This study traced the fate of dissolved organic carbon (DOC), total phenols (TP), electrical conductivity, pH, microbial counts, and phytotoxicity to cress ( L.) after soil application at doses equivalent to 80, 160, and 320 m ha. Vertisol (fine-clayey) and Loess (sandy loam) soils were treated and incubated at 12 or 25°C and at moisture contents maintained at 70% of field water capacity or gradually reduced from 70 to 20% without compensation. Temperature, rather than moisture content, had a major effect on removal rates of DOC and TP. The maximum combined effect of warm temperature and higher moisture content resulted in removal rates greater than those under cooler, drier conditions by factors of up to 1.8 and 4.1 for DOC and TP, respectively. Favorable biodegradation conditions were indicated by increased numbers of total soil microorganisms and fungi by factors of up to 26 and 5, respectively. A whole-soil bioassay was developed to assess the dynamics of residual soil phytotoxicity after OMW application. Phytotoxicity measurement in soil extract generally showed stronger inhibition or stimulation activity than measurement in whole soil, depending on soil type and OMW dose. The newly developed bioassay seems to be useful for the refinement of general recommendations regarding permitted OMW application doses.

Original and residual phytotoxicity of olive mill wastewater revealed by fractionations before and after incubation with Pleurotus ostreatus.

Concentrations of dissolved organic carbon (DOC) and total phenols (TP), and the phytotoxicity to cress (Lepidium sativum L.) were determined for three molecular-sized fractions of olive mill wastewater (OMW), <1000, 1000-5000, and >5000 Da, before and after incubation with Pleurotus ostreatus. The <1000-Da fraction contained 82% of the total DOC and 48% of the TP, and was the most phytotoxic. Ethyl acetate separation of aqueous and solvent fractions showed that the aqueous fraction contained 93% of the total DOC, 83% of the TP, and was most phytotoxic, indicating low importance of monomeric phenols. Incubation of whole OMW and of the separate size fractions with P. ostreatus mycelia reduced TP by factors of 4.3-5.3, but exerted diverse impact on phytotoxicity; overall, P. ostreatus efficacy in organic load removal and OMW detoxification was limited. Additional size fractionation of the incubated fractions revealed that most residual phytotoxicity was associated with low-molecular weight (MW) compounds originated from the <1000 Da fraction and not with low-MW byproducts from the degradation of higher-MW fractions and that polymerized metabolites were nonphytotoxic. Total phenols should not be used as sole indicators of the successful remediation of OMW.