Calibration and validation of the STICS crop model for managing wheat irrigation in the semi-arid Marrakech/Al Haouz Plain

In the first part of this work, the shoot growth module and grain yield of the STICS crop model were calibrated and validated by using field data which was collected from irrigated winter wheat fields in the Haouz plain near Marrakech. The calibration was performed on the thermal units between the four phenological stages that control the dynamics of leaf area index and the thermal unit between emergence and the beginning of grain filling. The plant phenology was calibrated for three fields monitored during the 2002/03 season. Evaluation of the grain yields and the temporal evolution of leaf area index were done for six validation fields during 2003/04. The results showed the significant accuracy of the model in simulating these variables, and also indicated that the plants mainly suffered from lack of nitrogen. The results in the second part show the potential of crop modeling to schedule irrigation water, on the assumption that the plants were growing under optimal conditions of fertilization. In this case, the model was used to manage the time of irrigation according to a threshold for water deficit. Various simulations displayed logical trends in the relationship between the grain yield and both the amount and timing of irrigation water. These results were finally compared with those obtained from real irrigation practices. For the particular climate of 2003/04, the comparison showed that 70 mm and 40 mm of water could be saved in case of early and late sowing, respectively

Water use efficiency and yield of winter wheat under different irrigation regimes in a semi-arid region

In irrigation schemes under rotational water supply in semi-arid region, the water allocation and irrigation scheduling are often based on a fixed-area proportionate water depth with every irrigation cycle irrespective of crops and their growth stages, for an equitable water supply. An experiment was conducted during the 2004- 2005 season in Haouz irrigated area in Morocco, which objective was 1) to evaluate the effects of the surface irrigation scheduling method (ex-isting rule) adopted by the irrigation agency on winter wheat production compared to a full ir-rigation method and 2) to evaluate drip irrigation versus surface irrigation impacts on water sav-ing and yield of winter wheat. The methodology was based on the FAO-56 dual approach for the surface irrigation scheduling. Ground measure- ments of the Normalized Difference Vegetation Index (NDVI) were used to derive the basal crop coefficient and the vegetation fraction cover. The simple FAO-56 approach was used for drip irrigation scheduling. For surface irrigation, the existing rule approach resulted in yield and WUE reductions of 22% and 15%, respectively, compared with the optimized irrigation sched-uling proposed by the FAO-56 for full irrigation treatment. This revealed the negative effects of the irrigation schedules adopted in irrigation schemes under rotational water supply on crops productivity. It was also demonstrated that drip irrigation applied to wheat was more efficient with 20% of water saving in comparison with surface irrigation (full irrigation treatment). Drip irrigation gives also higher wheat yield com-pared to surface irrigation (+28% and +52% for full irrigation and existing rule treatments re-spectively). The same improvement was ob-served for water use efficiency (+24% and +59% respectively)

Fertiledatepalm – a transdisciplinary collaboration project to ameliorate date palm cultivation via microbial inoculation, organic matter management and mixed cropping using nurse plants

Date palm is an important crop in Morocco, Tunisia and other drylands with a high agricultural, economic and cultural value. Harsh environmental conditions of those areas, further accelerated by climate change and the spread of root diseases, threaten date palm cultivation. To overcome limitations in productivity, high inputs of mineral fertilizers and pesticides are applied. However, these external inputs strongly affect the environment and livelihoods. The project aims at establishing an integrated microbe-assisted fertilization approach, combining the inoculation of native soil microbes, namely arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) during the different date palm growth stages, with adapted agricultural management practices using organic amendments and mixed-cropping in Morocco and Tunisia. As initial step, we established a culture collection of native microbes, isolated from date palm roots and rhizosphere composed of 24 AMF isolates including eight species from six genera, twelve bacterial endophyte isolates composed of Paenibacillus, Mycobacterium, and Achromobacter species and 34 PGPR isolates. Functional characterization of PGPRs revealed that around 50 % can solubilize phosphorus and potassium and between 9 % and 68 % have the ability to produce siderophores, hydrogen cyanid, chitinase, cellulase, amylase and protease. Consortia of microbes were formed and used for inoculations. Experiments under nursery conditions revealed that inoculation with AMF and PGPR combined with compost significantly increased growth of date palms as compared to non-amended controls enabling farmers to decrease the time prior to field transplantation. On-farm trials performed in productive date palm groves have shown that PGPR inoculation with or without mixed-cropping with sorghum as nurse plants significantly increase fruit characteristics such as fruit flesh weight as well as fruit length and diameter for up to 14 % and leaf macronutrient concentrations for up to 200 % while in addition enhancing the mycorrhizal potential of the soil. Our integrated fertilization approach is developed in a participatory approach with key stakeholders in so-called innovation platforms, working at laboratory, on-station and on-farm scale to best tackle farmers’ needs in order to facilitate adoption and implementation

Assessment of equity and adequacy of water delivery in irrigation systems using remote sensing-based indicators in semi-arid region, Morocco

The irrigation performance criteria of equity and adequacy are of primary concern for irrigation managers. The input data required at various scales to assess irrigation performance, often not available, need costly intensive field campaigns. Remote sensing techniques, used to directly estimate crop evapotranspiration (ETc), became recently an attractive option to assess irrigation performance from individual fields to irrigation scheme or river basin scale. In this study, ETc maps were obtained by combining the FAO-56 dual approach with relationships between crop biophysical variables and NDVI (Normalized Difference Vegetation Index), using high spatial resolution time series of SPOT and Landsat images. This approach was applied for 2002/2003 growing season in Haouz plain, Morocco. Remote sensing-based indicators, reflecting equity and adequacy of the irrigation water delivery were estimated. Adequacy was determined according to Relative Irrigation supply (RIS), Depleted Fraction (DF) and Relative Evapotranspiration (RET) and equity according to the coefficient of variation of ETc. The analysis of these indicators exhibits a great variability among fields. Variability in irrigation performance at all levels, associated factors and possible improvements are discussed. This study demonstrates how remote sensing-based estimates of water consumption provide better estimates of irrigation performance at different scales than the traditional field survey methods