Assessing Sprinkler Irrigation Performance Using Field Evaluations at the Medjerda Lower Valley of Tunisia

10 Pags., 6 Figs., 7 Tabls.Irrigation uniformity and wind drift and evaporation losses (WDEL) are major concerns for the design and management of sprinkler irrigation systems under arid or semi-arid conditions. Field trials were carried out to assess irrigation uniformity and WDEL under various wind velocities, sprinkler spacings and operating pressure heads. Based on experimental data, a frequency analysis was performed to infer the occurrence probability of a given uniformity coefficient (UC). In addition, statistical regressions were used to model WDEL as a function of different climatic variables. Increasing the operating pressure head improved uniformity at low wind speeds. It was shown that UC has been severely impaired at wind speeds above 4 m/s. In the prevailing wind conditions, the frequency analysis showed that a sprinkler spacing of 12 m × 12 m provided the best uniformity. In the local conditions, it is recommended to stop irrigation when wind velocity exceeds 4 m/s. Moreover, it was shown that wind speed and relative humidity were the main significant variables influencing WDEL.The authors are thankful to the INRGREF for the valuable support of this research.Peer reviewe

Assessing alternate furrow strategies for potato at the Cherfech irrigation district of Tunisia

39 Paf., 4 Tabl., 5 Fig. The definitive version is available at: http://www.sciencedirect.com/science/journal/15375110Irrigated agriculture faces intense competition for water in Mediterranean environments. In this paper, alternate furrow irrigation (AFI) was explored for a potato crop in the conditions of the Cherfech irrigation district, located in the Medjerda project of northern Tunisia. A field experiment was performed involving seven furrow irrigations in three irrigation treatments: alternate furrow irrigation, fixed furrow irrigation (FFI), and conventional furrow irrigation (CFI). Crop yield and water productivity were determined in all treatments. The experiment involved detailed irrigation evaluation and soil water measurements in the first three irrigation events. Soil infiltration (estimated with a surface irrigation model) was larger for CFI than for AFI or FFI. This finding was confirmed by the average irrigation depths, which amounted to 65, 60 and 91 mm for the AFI, FFI and CFI treatments, respectively. Application and irrigation efficiency were higher in FFI than in AFI, while in CFI efficiency was much lower. Water productivity (expressed as the ratio of yield to irrigation water) amounted to 8.0, 8.7 and 5.9 kg m−3 for the AFI, FFI and CFI treatments, respectively. Soil water-yield simulations indicated that alternate furrow irrigation did not result in reduced yield, neither for the experimental treatment nor for deficit irrigation scenarios characterised by six or five irrigation events. Alternate furrow irrigation stands as a simple management technique resulting in relevant water conservation in the local conditions.This research was partially funded by INRGREF (Tunisia), and by the Agencia Española de Cooperación y Desarrollo (AECID) of the Government of Spain, through grant A/7661/07.Peer reviewe

Day and night time sprinkler irrigated tomato: Irrigation performance and crop yield

31 Pag., 5 Tabl., 7 Fig.The effect of day time vs. night time sprinkler irrigation on irrigation performance and tomato crop yield is assessed in this paper for the conditions of Tunisia. Field experiments were performed at the experimental station of Cherfech under two rectangular sprinkler spacings: 24 × 18 m and 18 × 18 m, denoted as plots M1 and M2, respectively. Results of performance evaluations indicate a significant effect of climatic and operation conditions on irrigation uniformity and wind drift and evaporation losses (WDEL). Experimental data were used to calibrate and validate a ballistic solid-set sprinkler irrigation simulation model and a soil-water-yield crop model. Based on the analysis of the main meteorological parameters during the irrigation season, the validated models were used to simulate night time irrigation (characterised by moderate wind speed and evaporative demand). Simulation results indicate that night time irrigation would greatly improve performance in comparison to day time operation: WDEL decreased from 24 to 7%, while irrigation uniformity increased from 50 to 64% in M1 and from 71 to 80% in M2. Simulated results showed that night time irrigation decreased relative yield losses (from 26 to 16% in M1 and from 11 to 3% in M2), as well as improving the spatial variability of crop yield (simulated yield CV in M2 decreased from 17 to 6%). Adoption of night irrigation in the study area will finally depend on local socioeconomic and water management constraints.This research was partially funded by INRGREF (Tunisia), and by the Agencia Española de Cooperación y Desarrollo (AECID) of the Government of Spain, through grant A/7661/07.Peer reviewe

Improvement of durum wheat (Triticum durum) surface irrigation in swelling soils

7 Pags., 2 Figs., 7 Tabls.This study is targeted to improve surface irrigation performance of durum wheat in swelling soils. For this purpose, furrow and border irrigation trials were carried out and evaluated under different soil water depletion rates, furrow spacing and unitary inlet discharges. Irrigation was triggered whenever the soil water depletion rate reached a predetermined threshold. A comprehensive irrigation evaluation produced hydraulic, agronomic and economic indicators, such as application efficiency, distribution uniformity, crop yield, gross margin and water productivity. Experimental results showed that supplied water depths exceeded soil water deficits, inducing relevant vertical and lateral water losses. Although border and furrow irrigation crop yields were virtually tantamount (about 5.5 Mg/ha), furrow irrigation was the system of choice. An irrigation strategy based on a furrow spacing of 150 cm, an inlet discharge of 2 l/s/furrow and a soil water depletion rate of 30% required a gross water depth of 4300 m3/ha/yr and generated an optimum crop yield of 58 qx/ha. In the analyzed range of soil water depletion, the gross margin and water value amounted to 1064 - 1390 Tunisian Dinar per hectare (TD/ha) and 0.39 - 0.44 TD/m3, respectively, for a furrow spacing of 150 cm.The authors are thankful to the INRGREF for the valuable support of this research.Peer reviewe

Effect of Surface and Subsurface Drip Irrigation with Treated Wastewater on Soil and Water Productivity of Okra (Abemoschus esculentus) Crop in Semi-Arid Region of Tunisia

Under semi-arid conditions, irrigated agriculture faces hard competition for water. It is against this backdrop that appropriate management of irrigation techniques and water resources becomes a major concern. This study investigated the effect of surface (SDI) and subsurface drip irrigation (SSDI) with domestic treated wastewater (TWW) and fresh water (FW) on soil water dynamics, salinity, yield, and mineral nutrition of okra. The experimental design was set-up based on two adjacent plots according to the water quality: Fresh Water (FW) T1 and domestic Treated Wastewater (TWW) T2. Results showed that measured soil water contents (SWCs), under TWW treatment (T2), were greater than their corresponding measurements under FW (T1), and in particular at 35 cm depth. Meanwhile, for both water qualities, soil Electrical Conductivity (EC) registered at 5 cm depth was higher than those measured at 35 cm, with values ranging from 0.14 to 0.36 mS·cm−1 and from 0.20 to 0.47 mS·cm−m for T1 and T2, respectively. Regarding crop yield, a statistically significant increase (p = 0.05) in okra fresh yield was observed when TWW was used. Fresh yield in SDI was 2.55 t·ha−1 and 3.9 t·ha−1 in T1 and T2, respectively. Nevertheless, results indicated that lateral depth did not significantly affect okra fresh yield. Moreover, a significant higher irrigation water productivity (WPirrig) with TWW (1.08 ± 0.26 and 1.23 ± 0.18 kg m−1) was observed, which was nearly double those obtained with FW (0.72 ± 0.33 to 0.78 ± 0.18 kg m−1). Appropriate use of SSDI with TWW stands as an irrigation management technique to improve yield and irrigation water productivity of okra crops

Effect of Surface and Subsurface Drip Irrigation with Treated Wastewater on Soil and Water Productivity of Okra (<i>Abemoschus esculentus</i>) Crop in Semi-Arid Region of Tunisia

Under semi-arid conditions, irrigated agriculture faces hard competition for water. It is against this backdrop that appropriate management of irrigation techniques and water resources becomes a major concern. This study investigated the effect of surface (SDI) and subsurface drip irrigation (SSDI) with domestic treated wastewater (TWW) and fresh water (FW) on soil water dynamics, salinity, yield, and mineral nutrition of okra. The experimental design was set-up based on two adjacent plots according to the water quality: Fresh Water (FW) T1 and domestic Treated Wastewater (TWW) T2. Results showed that measured soil water contents (SWCs), under TWW treatment (T2), were greater than their corresponding measurements under FW (T1), and in particular at 35 cm depth. Meanwhile, for both water qualities, soil Electrical Conductivity (EC) registered at 5 cm depth was higher than those measured at 35 cm, with values ranging from 0.14 to 0.36 mS·cm−1 and from 0.20 to 0.47 mS·cm−m for T1 and T2, respectively. Regarding crop yield, a statistically significant increase (p = 0.05) in okra fresh yield was observed when TWW was used. Fresh yield in SDI was 2.55 t·ha−1 and 3.9 t·ha−1 in T1 and T2, respectively. Nevertheless, results indicated that lateral depth did not significantly affect okra fresh yield. Moreover, a significant higher irrigation water productivity (WPirrig) with TWW (1.08 ± 0.26 and 1.23 ± 0.18 kg m−1) was observed, which was nearly double those obtained with FW (0.72 ± 0.33 to 0.78 ± 0.18 kg m−1). Appropriate use of SSDI with TWW stands as an irrigation management technique to improve yield and irrigation water productivity of okra crops

Correction: Mahmoudi et al. Effect of Surface and Subsurface Drip Irrigation with Treated Wastewater on Soil and Water Productivity of Okra (<i>Abemoschus esculentus</i>) Crop in Semi-Arid Region of Tunisia. <i>Agriculture</i> 2022, <i>12</i>, 2048

The authors wish to make the following corrections to the original paper [...