# Analysis of Maize Sowing Periods and Cycle Phases Using Sentinel 1&2 Data Synergy
## Appendix A  
In November 2021, five farmers from the Brobbio-Pesio irrigation district (South Piedmont, Italy) were asked to answer a survey about maize cultivation practices and sowing periods.  
Answers provided by the farmers to each question (e.g., F1: answer from Farmer 1) were as follows.  
Question 1. In which period of the year is maize usually sown?  
1. F1. Usually, maize is sown twice per year. The first sowing is between the 10 th and 30 th of April; the second sowing occurs between the end of May and the first half of June. The choice of the sowing date depends mainly on soil moisture and weather conditions: soil temperature must be equal or above 13 \({}^{\circ}\)C, and there must be low risk of late frost.
2. F2. Maize is usually sown during the second half of April, or between 15 May and the first week of June. The period depends on the final product to be obtained (chopped maize or dry grain). The choice of sowing day is mainly driven by meteorological factors and soil temperature.
3. F3. According to the soil moisture and weather conditions, maize is sown from the beginning of April. The provider of seeds insures farmers against late frost: if the plant growth is blocked by late frosts in April, a new sowing can be done for free.
4. F4. If the soil moisture and weather conditions are optimal, the sowing period starts during the second half of April.
5. F5. Two growing seasons are usually planned. The first starts in April (usually during the last two weeks) and the second starts in late May.  
Question 2. In which period of the year is maize usually harvested?  
1. F1. Usually between September and October (e.g., October in 2021). The harvesting period depends on the intended use of maize, for which grains must reach optimum levels of moisture. A moisture of 30%-35% is required for chopped maize; a moisture of 25% is required for dry grain at the harvesting date (after that, grains are left to dry up to 12%).
2. F2. Chopped maize is usually harvested around 15 September. Dry grain maize is usually harvested around the middle of October.
3. F3. The most crucial factor is the optimum moisture of maize grains. Usually, the maize growing season is 120-130 days long.
4. F4. From the second half of September to late October, according to the required moisture of maize seeds and on weather conditions.
5. F5. Chopped maize is usually harvested at the beginning of September. The harvesting period for dry grain maize is usually October.  
Question 3. How are maize fields used during rest periods? (e.g., fallow lands, other crops)  
1. F1. Fields are usually cultivated with fodder grasses or winter wheat from autumn to spring. Typically, the rotation scheme for these months is: 1 year of winter wheat and then 3 consecutive years of fodder grasses. Maize is not cultivated in summer after winter wheat, because wheat is harvested in July.
2. F2. The crop rotation involves fodder grasses and barley (all cultivated in summer). The scheme is 5-6 years of fodder grasses, 1-2 years of maize, 1-2 years of barley.
3. F3. Maize fields are usually lying fallow during winter.  
F4. Croplands are located at high elevations, close to the Alps. Nothing is cultivated during winter.
* F5. Crop rotation is a summer practice. During winter, croplands are cultivated with fodder grasses. Question 4. Approximately, how long do the plants take to reach the maximum stage of growth from seed?
* F1. The maximum growing stage is reached by maize in the second half of July for those years when seeds are sown around 15 April.
* F2. Between June 20 th and the first week of July, according on the date of sowing.
* F3. The maximum stage of growth is usually reached in the first two weeks of July.
* F4. The maximum stage of growth is usually reached in the first two weeks of July.
* F5. According to the maize variety, the maximum growing phase is reached in mid-July.