27 research outputs found
Water status and yield response to deficit irrigation and fertilization of three olive oil cultivars under the semi-arid conditions of Tunisia
Sustainability of olive production is possible by adopting the modern techniques of irrigation and fertilization. In Tunisia, olive trees are usually cultivated in poor soils, under semi-arid conditions characterized by water scarcity. This study investigated the effects of different water supply and fertilization on leaf water status and crop yield of three different olive oil varieties cultivated in central Tunisia, during four experimental seasons (2014-2017). Three treatments were examined: trees conducted under rainfed conditions (TRF), which represented the control treatment, trees irrigated with 50% ETc (T50) and, finally, trees irrigated with 50% ETc and with additional fertilization (T50F). Leaf water content and potential, yield and water use efficiency have been monitored on three different varieties, Chetoui, Chemlali, and Koroneiki, which are quite typical in the considered region. For all the growing seasons, midday leaf water potentials were measured from April to September. Midday leaf water potentials (MLWP) were generally higher for the two irrigated treatments (T50 and T50F) than for non-irrigated trees (TRF). As the season proceeded, MLWPs tended to decrease during summer for all the treatments and varieties. The lowest values were observed for the non-irrigated trees, varying between -3.25 MPa to -4.75 MPa. Relative leaf water content followed the same trends of midday leaf water potentials. Chetoui showed the lowest yield, which did not exceed 1530 Kg/(ha year), even for irrigated and fertilized trees. On the other hand, the yields of Chemlali and Koroneiki, cumulated in the four years, reached the maximum value of about 20 tons/ha. For these two varieties, the cumulated yield obtained in the control treatment (TRF) resulted significantly lower than the corresponding of the other two treatments (T50 and T50F). The highest irrigation water use efficiency (WUE) was estimated for Chemlali (T50) and (TRF). WUE was equal to 1.22 Kg/m3 for Koroneiki under fertigated treatment (T50F). Application of the only water supply (50% ETc) or associated with fertilizer improved the tree water status and increased the productivity of Chemlali and Koroneiki varieties
Atténuation de l'impact du déficit hydrique sur une culture de petit pois par la combinaison d'amendements organiques et de systÚmes d'irrigation localisés
Cette recherche visait Ă Ă©valuer lâimpact de deux systĂšmes d'irrigation combinĂ©s Ă un amendement organique du sol, sur les paramĂštres hydrodynamiques et chimiques du sol et sur la productivitĂ© d'une culture de petit pois "Pisum sativum L. " soumise Ă des conditions de stress hydrique. Les rĂ©sultats obtenus ont montrĂ© que les rampes poreuses permettent une meilleure stabilitĂ© du stock d'eau avec une amplitude de 30 mm contre 50,7 mm pour le systĂšme au goutte Ă goutte et un dĂ©veloppement racinaire de petit pois plus intĂ©ressant avec une diffĂ©rence d'environ 2,5 cm par rapport au systĂšme de goutte Ă goutte. Le rendement n'a pas Ă©tĂ© significativement affectĂ© et nous avons enregistrĂ© une diffĂ©rence de 3,43% en faveur des rampes poreuses. En revanche, la nodulation des racines et la fixation symbiotique de l'azote dĂ©pendaient du systĂšme d'irrigation, et nous avons trouvĂ© une teneur en azote total plus Ă©levĂ©e pour les sols irriguĂ©s par des rampes poreuses qui a atteint 1,4 g/kg. Les amendements organiques ont augmentĂ© la teneur en humiditĂ© du sol Ă 24 et 25% pour la tourbe et le biochar respectivement par rapport au tĂ©moin. La croissance vĂ©gĂ©tative de la plante a Ă©galement Ă©tĂ© amĂ©liorĂ©e avec les amendements
Subsurface drip irrigated potato (Solanum tuberosum L.) with saline water under Tunisian climate
Field experiment was conducted at the Higher Institute of Agronomy of Chott Meriem (Tunisia) during the growing season (2011/2012) to investigate the effects of water quality on waterâs dynamic in soil (water potential, soilcmoisture distribution, waterâs stock in soil) and water use efficiency (WUE) to produce potato (Solanum tuberosum L.). Irrigation management treatments were fresh (1 dS m-1) and saline waters (4 dS m-1). Subsurface drip irrigation was used, a rate of 4 L h-1 applied at the same irrigation duration and interval. The results indicate that water content is more uniform using the saline water varies from 15 to 23% than treatment varies from 10 to 26%. The recorded changes occurred due to improving soil water distribution in root zone are explained by the increased salinity and the existence of a root system more intense level of treatment. Water quality has no direct effect on water use efficinency
Irrigation management strategies to improve Water Use Efficiency of potatoes crop in Central Tunisia
In Tunisia, the expansion of irrigated area and the semiarid climate make it compulsory to adopt strategies of
water management to increase water use efficiency. Subsurface drip irrigation (SDI), providing the application of
high frequency small irrigation volumes below the soil surface have been increasingly used to enhance irrigation
efficiency.
At the same time, deficit irrigation (DI) has shown successful results with a large number of crop in various
countries. However, for some crops like potatoes, DI is difficult to manage due to the rapid effect of water stress
on tuber yield. Irrigation frequency is a key factor to schedule subsurface drip irrigation because, even maintaining
the total seasonal volume, soil wetting patterns can result different during the growth period, with consequence
on crop yield. Despite the need to enhance water use efficiency, only a few studies related to deficit irrigation of
horticultural crops have been made in Tunisia.
Objective of the paper was to assess the effects of different on-farm irrigation strategies on water use efficiency
of potatoes crop irrigated with subsurface drip irrigation in a semiarid area of central Tunisia. After validation,
Hydrus-2D model was used to simulate soil water status in the root zone, to evaluate actual crop evapotranspiration
and then to estimate indirectly water use efficiency (IWUE), defined as the ratio between crop yield and total
amount of water supplied with irrigation.
Field experiments, were carried out in Central Tunisia (10⊠33â 47.0â E, 35⊠58â 8.1⊠N, 19 m a.s.l) on a potatoes
crop planted in a sandy loam soil, during the growing season 2014, from January 15 (plantation of tubers) to May
6 (harvesting). Soil water status was monitored in two plots (T1 and T2) maintained under the same management,
but different irrigation volumes, provided by a SDI system. In particular, irrigation was scheduled according to the
average water content measured in the root zone, with a total of 8 watering, with timing ranging between one and
three hours in T1, and between about half-an-hour and one-hour and a-half, in T2.
The validity of Hydrus-2D model was initially assessed based on the comparison between measured and estimated
soil water content at different distances from the emitter (RMSE values were not higher than 0.036). Then,
model simulations allowed to verify that it is possible to enhance irrigation water use efficiency by increasing
the frequency of irrigation even maintaining limited water deficit conditions during the full development stage
subsequent the crop tuberization. Experimental results, joined to model simulations can therefore provide useful
guidelines for a more sustainable use of irrigation water in countries characterised by semi-arid environments and
limited availability of water resources
Effects of different on-farm management on yield and water use efficiency of Potato crop cultivated in semiarid environments under subsurface drip irrigation
In Tunisia the amount of water for irrigated agriculture is higher than about 80% of the total resource.The increasing
population and the rising food demand, associated to the negative effects of climate change,make it crucial
to adopt strategies aiming to improve water use efficiency (WUE). Moreover, the absence of an effective public
policy for water management amplifies the imbalance between water supply and its demand. Despite improved
irrigation technologies can enhance the efficiency of water distribution systems, to achieve environmental goals it
is also necessaryto identify on-farm management strategies accounting for actual crop water requirement.
The main objective of the paper was to assess the effects of different on-farm managementstrategies (irrigation
scheduling and planting date) on yield and water use efficiency of Potato crop (Solanumtuberosum L.) irrigated
with a subsurface drip system, under the semi-arid climate of central Tunisia.
Experiments were carried out during three growing seasons (2012, 2014 and 2015) at the High Agronomic
Institute of ChottMariem in Sousse, by considering different planting dates and irrigation depths, the latter
scheduled according to the climate observed during the season. All the considered treatments received the same
pesticide and fertilizer management.
Experiments evidenced that the climatic variability characterizing the examined seasons (photoperiod, solar
radiation and average temperature) affects considerably the crop phenological stages, and the late sowing shortens
the crop cycle.It has also been demonstrated that Leaf Area Index (LAI) and crop yield resulted relatively
higher for those treatments receiving larger amounts of seasonal water. Crop yield varied between 16.3 t/ha and
39.1 t/ha, with a trend linearly related to the ratio between the seasonal amount of water supplied (Irrigation,
I and Precipitation, P) and the maximum crop evapotranspiration (ETm). The maximum crop yield was in
particular obtained for a value of this ratio equal to 1.45. Moreover, when increasing the seasonal pluviometric
deficit (P-ETm) and therefore the irrigation depth (I), standard deviations of crop yield tended to decrease, as a
consequence ofthe more uniform soil water content in the root zone.
In terms of agronomic water use efficiency (AWUE),differences among the investigated treatments varied in
a quite narrow range,due to thecombined effects of seasonal precipitation and atmospheric water demand on
irrigation depths and crop yield.On the other hand, when considering irrigation water use efficiency (IWUE), more
relevant differences between treatments were observed,being the higher values of IWUEgenerally associated to
the lower irrigation depths. However, to define the best irrigation management strategy it is necessary, from one
side, to consider the availability of water and from the other, to perform aneconomic analysis accounting for the
cost of water and the related benefits achievable by the farmer
Atténuation de l'impact du déficit hydrique sur une culture de petit pois par la combinaison d'amendements organiques et de systÚmes d'irrigation localisés
Cette recherche visait Ă Ă©valuer lâimpact de deux systĂšmes d'irrigation combinĂ©s Ă un amendement organique du sol, sur les paramĂštres hydrodynamiques et chimiques du sol et sur la productivitĂ© d'une culture de petit pois "Pisum sativum L. " soumise Ă des conditions de stress hydrique. Les rĂ©sultats obtenus ont montrĂ© que les rampes poreuses permettent une meilleure stabilitĂ© du stock d'eau avec une amplitude de 30 mm contre 50,7 mm pour le systĂšme au goutte Ă goutte et un dĂ©veloppement racinaire de petit pois plus intĂ©ressant avec une diffĂ©rence d'environ 2,5 cm par rapport au systĂšme de goutte Ă goutte. Le rendement n'a pas Ă©tĂ© significativement affectĂ© et nous avons enregistrĂ© une diffĂ©rence de 3,43% en faveur des rampes poreuses. En revanche, la nodulation des racines et la fixation symbiotique de l'azote dĂ©pendaient du systĂšme d'irrigation, et nous avons trouvĂ© une teneur en azote total plus Ă©levĂ©e pour les sols irriguĂ©s par des rampes poreuses qui a atteint 1,4 g/kg. Les amendements organiques ont augmentĂ© la teneur en humiditĂ© du sol Ă 24 et 25% pour la tourbe et le biochar respectivement par rapport au tĂ©moin. La croissance vĂ©gĂ©tative de la plante a Ă©galement Ă©tĂ© amĂ©liorĂ©e avec les amendements
Optimizing subsurface dripline installation depth with Hydrus 2D/3D to improve irrigation water use efficiency in the central Tunisia
The main objective of the work is to optimize drip installation depth for Eggplant crop irrigated with surface or subsurface drip irrigation systems to improve irrigation Water Use Effeciency (WUE), by means of field measurements and simulations carried out with Hydrus-2D model. Initially, a comparison between simulated Soil Water Contents (SWC) and the corresponding measured in two plots, in which laterals with coextruded emitters are laid on the soil surface (T0) and at 20 cm depth (T20), respectively. In order to choose the best position of the lateral, the results of different simulation run, carried out by choosing a deeper installation (T45) depth. Simulated SWCâs resulted fairly close to the corresponding measured at different distances from the emitter and therefore the model was able to predict SWCâs in the root zone with values of the Root Mean Square Error generally lower than 4%. This result is consequent to the appropriate schematization of the root distribution, as well as of the root water uptake. The values of WUE associated to the different examined installation depths tend to a very slight increase when the position of the lateral is situated on 20 cm and start to decrease for the higher depths
Application of STICS model in assessment of the effects of irrigation practices and soil properties on yield of a durum wheat (Triticum durum Desf.) cultivar in the irrigated area of Oued Rmel in Tunisia
International audienceThe progress in computer technology has enabled the development of crop models reproducing the behavior of a crop in a wide range of pedoclimatic conditions and technical itineraries. This work aims to study the impact of total available soil water in the root zone (TAW) on durum wheat yield (Triticum durum Desf.) as affected by irrigation regime in Mediterranean climatic conditions of Tunisia. In this work, STICS model was used to simulate effects of farmerâs irrigation practices in wheat in the pedoclimatic conditions of the irrigated area of Oued Rmel in Tunisia over a 20-year period. Assessment of irrigation practices in the study area was performed, compared to rainfed system, in terms of yield Original Research Article Annual Research & Review in Biology, 4(5): 747-765, 2014 748 and produced biomass at harvest. The model was calibrated to simulate the growth and development of winter wheat using the field observed crop data collected from three growing seasons in two locations in Tunisia. To carry out the study, three types of soil (S1, S2 and S3) in the Oued rmel irrigation scheme were chosen on the basis of their available soil water in the root zone (TAW). The study showed that the model adequately predicts crop yield and biomass. Simulation results showed that the farmersâ irrigation practice results, in higher grain yield and dry matter at harvest as compared to rainfed system. Simulated grain yield was significantly higher in soil with high TAW than in the other soils. Results showed that the highest difference (30%) in simulated grain yield, between the two water regimes, was obtained in soil having high TAW. Depending on the soil type, simulated dry matter at harvest increased from 4% to 12% compared to rainfed system
Application of STICS model in assessment of the effects of irrigation practices and soil properties on yield of a durum wheat (Triticum durum Desf.) cultivar in the irrigated area of Oued Rmel in Tunisia
International audienceThe progress in computer technology has enabled the development of crop models reproducing the behavior of a crop in a wide range of pedoclimatic conditions and technical itineraries. This work aims to study the impact of total available soil water in the root zone (TAW) on durum wheat yield (Triticum durum Desf.) as affected by irrigation regime in Mediterranean climatic conditions of Tunisia. In this work, STICS model was used to simulate effects of farmerâs irrigation practices in wheat in the pedoclimatic conditions of the irrigated area of Oued Rmel in Tunisia over a 20-year period. Assessment of irrigation practices in the study area was performed, compared to rainfed system, in terms of yield Original Research Article Annual Research & Review in Biology, 4(5): 747-765, 2014 748 and produced biomass at harvest. The model was calibrated to simulate the growth and development of winter wheat using the field observed crop data collected from three growing seasons in two locations in Tunisia. To carry out the study, three types of soil (S1, S2 and S3) in the Oued rmel irrigation scheme were chosen on the basis of their available soil water in the root zone (TAW). The study showed that the model adequately predicts crop yield and biomass. Simulation results showed that the farmersâ irrigation practice results, in higher grain yield and dry matter at harvest as compared to rainfed system. Simulated grain yield was significantly higher in soil with high TAW than in the other soils. Results showed that the highest difference (30%) in simulated grain yield, between the two water regimes, was obtained in soil having high TAW. Depending on the soil type, simulated dry matter at harvest increased from 4% to 12% compared to rainfed system