crop-winter wheat-climate data&Relationship between LGP, cycle, ccd, DOY

[maobw12]

Hello, the crop I have selected is winter wheat, because the growth phase of winter wheat is opposite to that of summer maize, soya bean and other crops, across the years, so I would like to ask if the input weather data is set to two years of data when simulating the maximum yield for winter wheat? For example, the monthly tif data set for July-December 2011 and January-June 2012 becomes npy data.Thank you for your answer.

[maobw12]

Hello, I have another question. 1, What is the relationship between LGP, LGPt5 and DOY, the input parameter cycle and the ccd derived by NB2? 2, I would like to ask if the following understanding is wrong or correct: 1) The input cycle is the longest and shortest cycle of crop growth and is not the crop start calendar DOY when NB2 calculates the maximum obtainable yield under rainfed and irrigated conditions, right? For example, if you enter the crop cycle parameters 200 165 270 as average cycle, minimum cycle, and longest cycle in that order, "then the code calculates the crop yield from the 200th day of the year". Is this understanding wrong or correct 2) NB2 For irrigated conditions, compare LGPt5 to cycle, move the calculation calendar within the allowable portion of LGPt5 to calculate potential crop yields, and select the highest yielding crop start date DOY, which is ccd; for rainfed conditions, compare LGP to cycle, move the calculation calendar within the allowable portion of LGP to calculate potential crop yields, and select the yielding highest crop start date DOY, which is ccd. ccd and DOY are one and the same concept. Is this understanding wrong or correct? 3) If, for calculating the potential crop yield of a raster pixel of an image, it is from the first day of the day, the second day ...... Day n all the way to the last day of the year, and see which day accumulates the most to the last day, and choose that day as the ccd? 3, I ran the ccd with a value of 365, so is the crop yield calculated from the 365th day of the year, or is it accumulated from the first day of the year to the 365th day of the year? Can you elaborate on the relationship between the concept of ccd and crop yield?

[NokuzaSezo97]

Hi @maobw12,

This is an extensive answer to deliver for each question. I would suggest to check out PyAEZ user guide for the workflow of Module 2, and GAEZ v4 documentation. In summary:

• The crop simulation tries to simulate the maximum potential yield for rainfed and irrigated condition simultaneously from the calendar range you've provided to simulate.

• The simulation check out the minimum cycle length required enough for yield generation using LGP for rainfed and LGPtx for irrigated conditions checked with minimum cycle length before going to simulate yield for each possible cycle. If they don't meet this requirement, the pixel location is skipped for yield calculation.

• For each cycle, the biomass, yield, fc1 and fc2 are calculated. For example, if you set up to simulate from 1st of January to December 31st, there will be 365 possible cycles. A single cycle is defined by three properties: starting DOY, cycle length, end DOY. Example for maize for cycle 1 will be as follow: starting DOY = Jan 1st cycle length = 90 ending DOY = Jan 1st + 90 days (March 31st) The climate data arrays are sliced according to these properties for the next series of calculation.

• From Module 2 outputs, ccd (crop calendar date or starting date) is the DOY when the maximum attainable yield is obtained, differently produced for rainfed and irrigated conditions, and the fc1 and fc2 are the values you will have at that CCD DOY.

Hope these clarify.

Regards,

Swun Wunna Htet

[maobw12]

thanks for your answer! Regarding the third one you mentioned： There are 365 different cycles. The first cycle is： starting DOY = Jan 1st cycle length = 90 ending DOY = Jan 1st + 90 days (March 31st) The second cycle is: starting DOY = Jan 2nd cycle length = 90 ending DOY = Jan 2nd + 90 days (April 1st) The following cycles are added one day at a time, am I understanding this correctly?