Figures (4)  Tables (2)

    • Figure 1. 

      Evolution of mean daily temperature (°C) and rainfall (mm) for the experimental period in (a) Noetinger (low halo-hydromorphic environment), (b) Laboulaye (intermediate halo-hydromorphic environment), and (c) Marcos Juárez (high halo-hydromorphic environment). The solid line corresponds to mean daily temperature values and the black bars to rainfall. The experimental period was from 02/11/2015 to 16/12/2015 in Noetinger and Marcos Juárez, and from 05/11/2015 to 15/12/2015 in Laboulaye.

    • Figure 2. 

      Blade proportion of tall wheatgrass (Thinopyrun ponticum) pastures during a late spring regrowth at a (a) low HHM, (b) intermediate HHM, and (c) high HHM sites, with two treatments (control: N0, dashed line and empty symbols; fertilized with 150 kg/ha of N: N150, dotted line and filled symbols). Vertical bars indicate the standard error (n = 5), and * denotes significant differences between treatments (p < 0.05). The experimental period was from Nov. 2nd to Dec. 16th at low and high HHM sites, and from Nov. 5th to Dec. 15th at the intermediate HHM sites.

    • Figure 3. 

      (a) Relationship between shoot biomass accumulation of tall wheatgrass (Thinopyrun ponticum) and the dry matter digestibility (DM digestibility, %). (b) Relationship between blade proportion of tall wheatgrass and DM digestibility. (c) Relationship between shoot biomass accumulation (kg DM/ha) of tall wheatgrass and blade proportion, at the end of a late spring regrowth, in all blocks and replicates at low HHM site (square symbols, low halo-hydromorphism), intermediate HHM site (circle symbols, intermediate halo-hydromorphism), and at high HHM site (triangle symbols, high halo-hydromorphism), in control treatments (N0, empty symbols) and fertilized with 150 kg/ha of N (N150, filled symbols).

    • Figure 4. 

      Relationship between shoot biomass accumulation (kg MD/ha) of tall wheatgrass (Thinopyrun ponticum) and crude protein content (%), at the end of a late spring regrowth, in all blocks and replicates at low HHM site (square symbols, low halo-hydromorphism), intermediate HHM site (circle symbols, intermediate halo-hydromorphism), and at high HHM site (triangle symbols, high halo-hydromorphism), in control treatments (N0, empty symbols) and fertilized with 150 kg/ha of N (N150, filled symbols).

    • Low HHM Intermediate HHM High HHM
      SOM (g/kg) 15 ± 2.6 17.6 ± 0.5 31.3 ± 1.4
      P-Bray 1 (mg/kg) 39.20 ± 7.41 18.20 ± 2.08 20.60 ± 2.66
      pH 9.94 ± 0.13 8.18 ± 0.05 7.34 ± 0.11
      Soil Ec1:2.5 (dS/m)* 0.97 ± 0.13 3.86 ± 0.40 4.49 ± 0.14
      Water table EC (dS/m)* 2.03 ± 0.09 7.40 ± 0.40 7.85 ± 0.35
      Water table depth (cm)* 85 ± 10 134 ± 6 31 ± 3
      * There were no significant differences (p < 0.05) between values at the beginning and at the end of the experiment, so the average value of both samples is presented.

      Table 1. 

      Soil organic matter (SOM, g/kg), phosphorus concentration (P-Bray1, mg/kg), and pH at the beginning of the experimental period; average soil salinity between the beginning and end of the experimental period (Soil EC1:2.5, (dS/m) in the 0−20 cm soil layer) and water table attributes (EC in dS/m and average water table depth (cm) between the beginning and end of the experimental period) in tall wheatgrass (Thinopyrum ponticum) pastures from three sites with different halo-hydromorphic (HHM) conditions (low, intermediate, and high). Values are means ± 1 standard error.

    • Variables Low HHM Intermediate HHM High HHM
      N0 N150 N0 N150 N0 N150
      Dry matter digestibility (DMD, %) 59 ± 0.54 b 60 ± 0.30 a 60 ± 1.16 b 64 ± 0.27 a 63 ± 0.45 b 65 ± 0.35 a
      Neutral detergent fibre (NDF, %) 67 ± 0.32 68 ± 0.68 63 ± 0.71 a 61 ± 0.64 b 64 ± 0.60 a 62 ± 0.78 b
      Crude protein (CP, %) 10 ± 0.33 b 16 ± 0.44 a 12 ± 0.19 b 15 ± 0.64 a 14 ± 0.65 16 ± 0.91
      Different letters indicate significant differences between nitrogen treatments within each site (p < 0.05).

      Table 2. 

      Variables related to forage quality of tall wheatgrass (Thinopyrun ponticum) at the end of late spring regrowth, without (N0) and with N fertilization (N150; 150 kg/ha of N in the form of urea), from three sites with different halo-hydromorphic (HHM) conditions (low, intermediate, high).