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

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

Evaluation of different crop sequences for wheat and maize in sandy soil

The objective of this paper was to assess four crop sequence system including wheat and maize grown in sandy soil of Upper Egypt with respect to the applied irrigation amount for each crop sequence, total production and water productivity. Two field experiments were conducted in Egypt during 2013/14 and 2014/15 growing seasons. Each experiment included four crop sequences: maize then wheat (CS1); maize, short season clover (SSC) then wheat (CS2); cowpea, SSC then wheat (CS3); cowpea intercropped with maize, SSC then wheat (CS4). The lowest amount of applied water was added to CS1 which resulted with low value of wheat and maize yield and the lowest water productivity. The highest amount of applied water was applied to CS2 and CS4 (similar values). The highest wheat yield and water productivity were obtained in CS3. The highest maize yield and water productivity was obtained from CS4. The highest total production (170.88 and 213.43 CU ha-1 in the 1st and 2nd season, respectively) and water productivity (0.093 and 0.114 CU m-3 in the 1st and 2nd season, respectively) for the studied crop sequences was obtained from CS3. In conclusion, higher water productivity for wheat in sandy soil can be attain by cultivating two legume crops before it (CS3); and for maize, it should be intercropped with a legume crop (CS4).</p