Multiple cropping zones - rain-fed conditions
In the Global AEZ crop suitability analysis, the LUTs considered refer to single cropping of sole crops, i.e., each crop is presumed to occupy the land only once a year and in pure stand. Consequently, in areas where the growing periods are sufficiently long to allow more than one crop to be grown in the same year or season, single crop yields do not reflect the full potential of total time and space available per unit area of land for rain-fed production.
To assess the multiple cropping potential, a number of multiple cropping zones have been defined through matching both growth cycle and temperature requirements of individual suitable crops with time available for crop growth. For rain-fed conditions this period is approximated by the LGP, i.e., the number of days during which both temperature and moisture conditions permit crop growth.
For the definition of multiple cropping zones four types of crops are distinguished: thermophilic crops requiring warm temperatures, cryophilic crops performing best under cool and moderately cool conditions, hibernating crops, and wetland crops with specific water requirements. Furthermore, the crops are subdivided according to growth cycle length, namely of less or more than 120 days duration, respectively. According to the above criteria, the following nine zones were classified and mapped:
(A) | Zone of no cropping (too cold or too dry for rain-fed crops) |
(B) | Zone of single cropping |
(C) | Zone of limited double cropping (relay cropping; single wetland rice may be possible) |
(D) | Zone of double cropping (sequential cropping; wetland rice not possible) |
(E) | Zone of double cropping (sequential cropping; one wetland rice crop possible) |
(F) | Zone of limited triple cropping (partly relay cropping; no third crop possible in case of two wetland rice crops) |
(G) | Zone of triple cropping (sequential cropping of three short-cycle crops; two wetland rice crops possible) |
(H) | Zone of triple rice cropping (sequential cropping of three wetland rice crops possible) |
Multiple cropping zones - rain-fed conditions
Delineation of multiple cropping zones for rain-fed conditions is solely based on agro-climatic attributes calculated during AEZ analysis. The following attributes were used in the definition of cropping zones:
| LGP | length of growing period, i.e., number of days when temperature and soil moisture permit crop growth. |
| LGP t = 5 | number of days with mean daily temperatures above 5ºC. |
| LGP t = 10 | number of days with mean daily temperatures above 10ºC. |
| TS t = 0 | accumulated temperature
(degree-days) on days when mean daily temperature  0ºC. |
| TS t = 10 | accumulated temperature
(degree-days) on days when mean daily temperature 10ºC. |
| TS-G t = 5 | accumulated temperature
during growing period when mean daily temperature 5ºC. |
| TS-G t = 10 | accumulated temperature
during growing period when mean daily temperature 10ºC. |
These attributes have been used as delineation criteria for multiple cropping zones under rain-fed conditions in respectively the tropics and the subtropics/temperate zones.
Delineation of multiple cropping zones under
rain-fed conditions