Sink-pulled simulation of the maize crop

Current maize simulation models (CORNF and CERES-Maize) are source-oriented , in which kernel weight is predicted without simulating sink demand of the kernels. The major goal of this research is to develop a physiologically sound model to simulate vegetative and reproductive growth of maize;The objectives of this study are: (1) to develop a subroutine to predict maize vegetative development; (2) to develop mechanisms to calculate silk growth, fertilization of the silk, and kernel set; (3) to address some of the problems that CENTLI has and use it to simulate grain filling period; (4) to develop a mechanism to predict the impact of both temperature and water stresses on maize growth and development; (5) to test the physiological implication of the developed model;Maize-S was validated against field data collected from two locations in Iowa in 1995 and 1996 for two maize hybrids planted at two different planting dates were used. To evaluate accuracy of predictions, the mean root square error and percent error averaged over time were calculated for both Maize-S and CERES-Maize;Maize-S predictions for leaf and stem weight were more accurate than CERES-Maize. CERES-Maize predictions for kernel number were more accurate than Maize-S predictions in four locations. This might be attributed to the method that CERES-Maize uses to calculate kernel number, wherein a stress factor is used to reduce kernel number. Maize-S does not account for any stress during kernel set. CERES-Maize predictions for kernel number were more accurate than Maize-S at two locations;Sensitivity analysis using Maize-S with conditions of +5 or -5°C from observed air temperatures reveals major changes in plant behavior. Maize-S output shows that high temperature cause silking to occur earlier than normal with an average of 3.2 days for each 1°C increase in temperature. A reduction in leaf area, aboveground nongrain and grain weights were also observed. Whereas cool temperature prolongs the growing season, and consequently increasing both aboveground nongrain and grain weights and leaf area;Sensitivity analysis using Maize-S with the condition of 5% increase in solar radiation did not affect number of days to silking, but increase the number of days to maturity by an average of 6 days. Aboveground nongrain and grain weights were also increased, whereas leaf area was not affected;Furthermore, Maize-S output shows that when defoliation occurs on weekly intervals after silking up to three weeks reduced kernel yield, weight per kernel, and kernel number;Further improvement in estimating water stress is recommended. Other improvements would be the capability to simulate prolificacy, and the estimation of nitrogen stress effects on yield

Approaches to increase the resiliency of Egyptian agriculture to climate change

Climate change is expected to affect agricultural production in direct and indirect pathways. The increase in mean temperatures directly accelerates crop development, the change in seasonal precipitation amounts together with increasing evaporative demand can indirectly lead to more drought stress for crops. In Egypt, the agricultural sector is highly vulnerable to climate change due to its dependence on the Nile River for irrigation, increasing soil salinity by sea water intrusion and soil deterioration as a result of decomposition of its organic contents. In this article, previous research carried out in Egypt on climate change assessments on water resources (the Nile River and rainfall on the north coast of Egypt), crop evapotranspiration, crop water requirements, crop yield, agricultural soils and national cultivated area are reviewed. Furthermore, the implemented actions to increase crop resilience to climate change were discussed. Additionally, the procedures used to reduce greenhouse gases emission were also reviewed. Keywords: Water resources, soil resources, climate-resilient crops, greenhouse gases emissions, carbon sequestration, biogas productio

Sustainable intensive cropping to reduce irrigation-induced erosion: Intercropping systems under surface irrigation practice

The objective of this paper was to compare between the effects of two production packages on the applied irrigation amount, crop yield and soil organic matter contents as indicators of the existence soil loss under surface irrigation. These packages were: farmer practices (FP, resulted in application of large amount of irrigation water), which applied to wheat and sunflower and improved management practices (IMP, reduced the applied irrigation water), where pea and cowpea intercropped with wheat and sunflower, respectively. The results indicated that using the IMP resulted in irrigation water saving by 23 and 22% and yield increase by 13 and 14% for wheat monoculture and intercropped, respectively compared to the FP. Similarly, the water saving for sole and intercropped sunflower was 21 and 20% and yield increase was 11 and 17%, respectively when IMP was implemented. Soil organic content was increased after the fourth growing season by 11%, when intercropping systems were implemented, compared zero-time. Land equivalent ratio values were 1.37 and 1.53 for wheat and sunflower intercropping systems averaged over the two season. In conclusion, using raised beds and intercropping systems in IMP package reduce applied water can be useful in reducing soil loss under surface irrigation practice

Decreasing maize production-consumption gap by intercropping with upland rice using different planting densities under deficit irrigation

A two-year field experiment was conducted in 2018 and 2019 at Gemmiza Agricultural Research Station (Lat. 31.03° N, Long. 30.88° E, 8 m a.s.l.); Gharbia Governorate; Egypt. The aim was to use untraditional sowing method to intercrop maize with upland rice using three maize planting densities (25, 37.5 and 50% of its recommended density) and application of two deficit irrigation treatments (irrigation every 9 and 12 days), in addition to irrigation every 6 days (control) and to study its effect on the yield of both intercrops, competitive relationships and farmer’s income. The results indicated that the highest value of rice yield and its components were found under irrigation every 6 days and 25% maize planting density intercropped with rice. Whereas, the highest value of maize yield and its components were found under irrigation every 9 days and 50% maize planting density intercropped with rice, which also obtained the highest land and water equivalent ratios, area time equivalent ratio, and land equivalent coefficient. Furthermore, the highest total income and monetary advantage index were obtained under irrigation every 9 days and 50% maize planting density intercropped with rice. Thus, these results implied that intercropping maize with upland rice can solve part of the maize production-consumption gap through increasing its production without using additional lands or water.  Keywords: Land and water equivalent ratios, percentage of land saved, area time equivalent ratio, land equivalent coefficient, monetary advantage index, Rice, Maize, Egyp

Sustainable intensive cropping to reduce irrigation-induced erosion: Changing cropping sequence under sprinkler irrigation practice

The objective of this paper was to evaluate the effect of four crops sequence (one conventional and three suggested) on the applied irrigation amount, the resulted yield and soil nitrogen percentage as indicators of the existence of soil loss. These crops sequences were: farmer’s crop sequence (FCS) and three crop sequences implemented using improved management practices (maize, clover then wheat (CS1); cowpea, clover then wheat (CS2) and cowpea intercropped with maize, clover then wheat (CS3). The results indicated that the applied water for wheat was respectively reduced by 16, 18 and 19% in CS1, CS2 and CS3 and yield was increased by 30, 55, and 43%, compared to the FCS. For maize, the applied water was reduced by 15% in CS1 and CS3 and yield was increased by 5 and 8%, respectively, compared to the FCS. The highest value of soil nitrogen percentage was obtained from cultivation of CS2, as a result of existence of cowpea and short season clover. In conclusion, optimizing the applied irrigation water to maize and wheat and increasing number of legume in the crop sequence can be one of the factors that improve soil water holding capacity and reduce soil loss

Response of spring wheat (Triticum aestivum) to deficit irrigation management under the semi-arid environment of Egypt: field and modeling study

In many areas of the world, water shortages prevail and threaten food production. Deficit irrigation was commonly investigated in dry areas as a precious and sustainable production approach. Using the CropSyst model to simulate the effects of different deficit irrigation treatments could help draw conclusions and save time, effort, and money. Therefore, the aims of this research were (i) to calibrate and validate the CropSyst model for wheat under different sustained and phenological stage-based deficit irrigation treatments, (ii) to simulate the impacts of the latter treatments on limiting wheat yield reduction. Two field experiments were conducted in Nubaria (Egypt), representing an arid environment. They included seven irrigation treatments: (1) 100%, (2) 75%, or (3) 50% of crop evapotranspiration (ETc) during the whole crop cycle; (4) 50% ETc at tillering only, or (5) at booting only, or (6) at grain filling only, or (7) at both tillering and grain filling, with the replenishment of 100% ETc to the treatments (4) to (7) in the remaining phenological stages. The results revealed that phenological stage-based deficit irrigation of wheat resulted in lower yield reduction compared to sustained deficit irrigation treatments, with a 6% yield reduction when 50% ETc was applied at the booting stage. Wheat yield loss was reduced to 4 or 6% when 95 or 90% of ETc were applied, respectively. The CropSyst model accurately simulated wheat grain and total dry matter under deficit irrigation with low RMSE value. In conclusion, the CropSyst model can be reliably used for evaluating the strategy of planned deficit irrigation management in terms of wheat production under the arid environmen

Sink-pulled simulation of the maize crop

Current maize simulation models (CORNF and CERES-Maize) are "source-oriented", in which kernel weight is predicted without simulating sink demand of the kernels. The major goal of this research is to develop a physiologically sound model to simulate vegetative and reproductive growth of maize;The objectives of this study are: (1) to develop a subroutine to predict maize vegetative development; (2) to develop mechanisms to calculate silk growth, fertilization of the silk, and kernel set; (3) to address some of the problems that CENTLI has and use it to simulate grain filling period; (4) to develop a mechanism to predict the impact of both temperature and water stresses on maize growth and development; (5) to test the physiological implication of the developed model;Maize-S was validated against field data collected from two locations in Iowa in 1995 and 1996 for two maize hybrids planted at two different planting dates were used. To evaluate accuracy of predictions, the mean root square error and percent error averaged over time were calculated for both Maize-S and CERES-Maize;Maize-S predictions for leaf and stem weight were more accurate than CERES-Maize. CERES-Maize predictions for kernel number were more accurate than Maize-S predictions in four locations. This might be attributed to the method that CERES-Maize uses to calculate kernel number, wherein a stress factor is used to reduce kernel number. Maize-S does not account for any stress during kernel set. CERES-Maize predictions for kernel number were more accurate than Maize-S at two locations;Sensitivity analysis using Maize-S with conditions of +5 or -5°C from observed air temperatures reveals major changes in plant behavior. Maize-S output shows that high temperature cause silking to occur earlier than normal with an average of 3.2 days for each 1°C increase in temperature. A reduction in leaf area, aboveground nongrain and grain weights were also observed. Whereas cool temperature prolongs the growing season, and consequently increasing both aboveground nongrain and grain weights and leaf area;Sensitivity analysis using Maize-S with the condition of 5% increase in solar radiation did not affect number of days to silking, but increase the number of days to maturity by an average of 6 days. Aboveground nongrain and grain weights were also increased, whereas leaf area was not affected;Furthermore, Maize-S output shows that when defoliation occurs on weekly intervals after silking up to three weeks reduced kernel yield, weight per kernel, and kernel number;Further improvement in estimating water stress is recommended. Other improvements would be the capability to simulate prolificacy, and the estimation of nitrogen stress effects on yield.</p

Water requirements for wheat and maize under climate change in North Nile Delta

Determination of water requirements for wheat and maize under climate change is important for policy makers in Egypt. The objectives of this paper were to calculate (i) ETo and (ii) water requirements for wheat and maize crops grown in five governorates (Alexandria, Demiatte, Kafr El-Sheik, El-Dakahlia and El-Behira) located in North Nile Delta of Egypt under current climate and climate change. ECHAM5 climate model was used to develop A1B climate change scenario in 2020, 2030 and 2040. Monthly values of evapotranspiration (ETo) under the different scenarios in these governorates were calculated using Hargreaves-Samani equation (H-S). Then, these values were regressed on ETo values previously calculated by Penman-Monteith equation (P-M) and linear regression (prediction equations were developed for each governorate). The predicted ETo values were compared to the values of ETo calculated by P-M equation and the deviations between them were very low (RMSE/obs=0.04-0.06 mm and R2 =0.96-0.99). Water requirements for wheat and maize were calculated using BISm model under current climate and in 2020, 2030 and 2040. The results showed that average annual ETo would increase by low percentage in 2020 and 2030. However, in 2040 the increase would reach 8%. Water requirements are expected to increase by 2-3% for wheat and by 10-15% for maize, which would result in reduction of the cultivated area. Thus, it is very important to revise and fix the production system of wheat and maize, in terms of the used cultivars, fertilizer and irrigation application to overcome the risk of climate change

Irrigation Scheduling Calculator (ISC) to improve water management on field level in Egypt

The developed model is MS excel sheet called “Irrigation Scheduling Calculator, ISC”. The model requires to input daily weather data to calculate daily evapotranspiration using Penman-Monteith equation. The model calculates water depletion from the root zone to determine when to irrigate and how much water should be applied. The charge from irrigation pump is used to calculate how many hours should the farmer run the pump to deliver the needed amount of water. ISC model was used to developed irrigation schedule for wheat and maize planted in El-Gharbia governorate. The developed schedules were compared to the actual schedules for both crops. Furthermore, CropSyst model was calibrated for both crops and run using the developed schedules by ISC model. The simulation results indicated that the calculated irrigation amount by ISC model for wheat was lower than actual schedule by 6.0 mm. Furthermore, the simulated wheat productivity by CropSyst was higher than measured grain and biological by 2%. Similarly, the calculated applied irrigation amount by ISC model for maize was lower than actual schedule by 79.0 mm and the productivity was not changed