Mapping soil salinity in 3-dimensions using an EM38 and EM4 Soil inversion modelling at the reconnaissance scale in central Morocco
H. Dakak, J. Huang, A. Zouahri, A. Douaik & J. Triantafilis, Soil Use and Management, doi: 10.1111/sum.12370
Abstract:
Large areas of Morocco require irrigation and although good quality water is available in dams, farmers augment river water with poorer quality ground water, resulting in salt build-up without a sufficient leaching fraction. Implementation of management plans requires baseline reconnaissance maps of salinity. We developed a method to map the distribution of salinity profiles by establishing a linear regression (LR) between calculated true electrical conductivity (r, mS/m) and electrical conductivity of the saturated soil-paste extract (ECe, dS/m). Estimates of r were obtained by inverting the apparent electrical conductivity (ECa, mS/m) collected from a 500-m grid survey using an EM38. Spherical variograms were developed to interpolate ECa data onto a 100 m grid using residual maximum likelihood. Inversion was carried out on kriged ECa data using a quasi-3d model (EM4Soil software), selecting the cumulative function (CF) forward modelling and S2 inversion algorithm with a damping factor of 3.0. Using a ‘leave-one-out cross-validation’ (LOOCV), of one in 12 of the calibration sites, the use of the q-3d model yielded a high accuracy (RMSE = 0.42 dS/m),
small bias (ME = 0.02 dS/m) and Lin’s concordance (0.91). Slightly worse results were obtained using individual LR established at each depth increment overall (i.e. RMSE = 0.45 dS/m; ME = 0.00 dS/m; Lin’s = 0.89) with the raw EM38 ECa. Inversion required a single LR (ECe = 0.679 + 0.041 9 r), enabling efficiencies in estimating ECe at any depth across the irrigation district. Final maps of ECe, along with information on water used for irrigation (ECw) and the characterization of properties of the two main soil types, enabled better understanding of causes of secondary soil salinity. The approach can be applied to problematic saline areas with saline water tables.
Keywords: Soil mapping, electrical conductivity, soil salinity, baseline data, EM inversion modelling
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Wide crosses of durum wheat (Triticum durum Desf.) reveal good disease resistance, yield stability, and industrial quality across mediterranean sites
Meryem Zaïm, Khaoula El Hassouni, Fernanda Gamba, Abdelkarim Filali-Maltouf, Bouchra Belkadi, Ayed Sourour, Ahmed Amri, Miloudi Nachit, Mouna Taghouti, Filippo M. Bassi, Field Crops Research 214 (2017) 219-227 journal homepage: www.elsevier.com/locate/fcr
Abstract:
Durum wheat (Triticum durum Desf.) breeders over the past century have increased the productivity and resilience of this crop via strong selection applied to genes controlling agronomically important traits. Along this process, some of the primitive genetic diversity of this species was lost. A debate exists on whether or not some of the original primitive diversity should be re-introgress into modern germplasm in order to facilitate new improvements. Here, the possible negative effects of re-introducing primitive diversity were assessed by comparing the performances of three ICARDA elites and four commercial cultivars against seventeen durum wheat wide crosses, generated by hybridization of elites and Triticum dicoccoides, T. araraticum, and Aegilops speltoides. The material was grown in Lebanon, Algeria and 10 environments in Morocco. Tested under natural inoculation
against Lr14a virulent strains of leaf rust as well as tan spot races 4 and 6, revealed that wide crosses had significantly higher levels of resistance. Further, the use of a selection index that combined selection for grain yield potential and stability revealed that 14 wide crosses performed better than any of the elites or cultivars. Finally, testing quality traits at four sites revealed that wide crosses had significantly higher grain size and protein content than the other two germplasm classes, while no significant difference could be observed for gluten strength. Only in the case of yellow pigment, an industrially important trait for durum wheat, one variety (‘Tomouh’) outperformed all other classes, even though wide crosses lines also achieved good scores. Hence, it was not possible to identify any negative drag in the use of wide crosses for improving durum wheat modern germplasm, with the partial exception of yellow pigment.
Keywords: Durum wheat, Wild relatives, Tan spot, Leaf rust, GxE, Yellow pigment, Gluten strength, Protein content
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Elucidation of functional chemical groups responsible of compost phytotoxicity using solid-state 13 C NMR spectroscopy under different initial C/ N ratios
Khalid Azim, Youssef Faissal, Brahim Soudi, Claude Perissol, Sevastianos Roussos, Imane Thami Alami, Environmental Science and Pollution Research llttps://doi.org/10.1007/s 11356-017.0704-9
Abstract:
More than 1 million tons of fresh organic wastes is produced in the Souss-Massa region in Morocoo. Tomato organic residues represent more than 25% of the total organic wastes and are deposited in uncontrolled landfills. Thus, composting can representes valuable and pertinent solution to this environmental problem. The objectives of this experiment are to identify the potential functional groups responsible for compost phytotoxicity and to determine the optimum initial carbon to nitrogen ratio (C/N) for maximum recovery of tomato residues. The experiment consisted of the variation of the initial ON ratios (25, 30, 35, and 40) using mixtures of different raw materials (tomato residues, melon residues. olive mill pomace, and sheep manure). Physiocochemical parameters (pH, electricity conductivity, C/N ratio, and humic acid/fulvic acid ratio) were determined and spectroscopie analyses (UV-vis and NMR-13C) were performed during the composting process along with quality parameters (germination and phytotoxicity tests) at the end. The results showed that the compost with the initial C/N ratio of 35 is the most humified with the least phytotoxic effect. The germination and phytotoxicity tests were negatively corelated with the methoxyl/N-alkyl.C ratio and O-alkyl.C. These two functional groups are probably the origin of phytotoxicity expression in compost quality tests. Thus, a simple and precise quality test could be performed to evaluate directly the phytotoxicity and maturity of compost.
Keywords: NMR-13C, Tomato residue, Compost, Phytoxicity, C/N ratio
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