Simulation of crop management options for USM Var 10 Maize (Zea mays L.) variety / Johanna B. Manslao

Thesis (Master of Science in Agricultural Engineering) -- Central Luzon State University, June 2018.

This study was conducted to simulate the crop management options for USM Var
10 maize variety using the Decision Support System for Agrotechnology Transfer
(DSSAT)version4.7. Specifically, it aimed to calibrate and validate the DSSATCERES
Maize model for USMVar 10 maize variety.

A field was selected, prepared and USMVar 10maizewas sown in nine plots.
Three sowing dates (SD,-August8,2017, SD,-August 18,2017andSD,-August28,
2017)with a 10-day interval was use and three plots were sown for each sowing date.
The second sowing date data set was used for model calibration while the remaining two
sowing dates (August 8, 2017andAugust28, 2017) data sets were used for the model
validation. Phenological stages and yield were observed, measured and used as datasets
for the model calibration and validation.

The Crop Genetic Coefficients (CGCs) for USMVar 10 were generated,
established and set as default in the simulations. Generated CGCs were P,=262.6,
P,=1.535,P,=968.0,G=609.4,G,=15.48andPHINT=38.90.
Based from the result of model calibration, computed values of Root Mean
Square(RMSE) and normalized Root Mean Square (nRMSE) revealed 1.47and0.026%
respectively, which implies that the simulation is highly accurate and acceptable, thus,

DSSAT is able to predict with reliable accuracy in response to climate, geographical, soil
properties and crop management inputs. Calculations of the nRMSE showed an
acceptable value of 7.88% and 0.55% for the two remaining sowing dates which also
imply an acceptable simulation outputs.

After obtaining good and acceptable values in the simulations as reflected by
acceptable value of RMSE and nRMSE, the model was used to simulate different
scenarios (sowing dates, fertilizer levels, sowing distance and irrigation scenarios) to
formulate crop management options for USM Var 10 maize variety.

The results of the simulations have suggested the recommended crop management
options for a good yield of the USM Var 10 maize variety. For the rainfed scenario, the
recommended crop ent was for the crop sown on August 8, 2017 with a
simulated yield of 7,619 kg/ha, applied with 200 kg/ha of Urea as side dressing on its 25"
DAS and sown with a distance of70 cm x 25 cm, respectively. On the other hand, for the
rainfed and irrigation at 50% available water scenario, the recommended crop
management option was for the crop sown as early as June 9, 2017 with a simulated yield
of 9,708 kg/ha.

This can be reliably achieved if200 kg/ha of Urea is applied as side dress
on the 25" DAS and sown with a distance of70cm x 25 cm. Irrigation water requirement
for the whole growth duration of these scenario was 173.32 mm applied in several
occasion. The scenario would only be recommended for sowing in area of North
Cotabato on sites with access to either surface irrigation of shallow tube well.