CROP REQUIREMENTS 
LRND UNITS 
SLOPE % 
SOIL TEXTURE 
SOIL depth: 
MAIZE/SORGHUM 
SI 
1, 2 
3, 4 
3 : 
S2 
1, 2, 3 
2, 3, 4, 5 
2, 3 : 
RICE 
SI 
1 
4, 5 
2, 3 : 
S2 
1 
3, 4, 5 
2, 3 : 
PINEAPPLE 
SI 
1, 2 
3, 4 
3 : 
S2 
1, 2, 3 
2, 3, 4, 5 
2, 3 
INHER. FERT 
SOIL DRAINAGE ! FLOODING RISK! 
MAIZE/SORGHUM 
; ; 
SI 
2, 3 
4, 5 : i : 
S2 
1, 2, 3 
3, 4, 5, 6 : l, 2 : 
RICE 
j ; 
SI 
2, 3 
l, 2 : i : 
S2 
2, 3 
l, 2, 3, 4 : l, 2 : 
PINEAPPLE 
| ; 
SI 
2, 3 
4, 5 : i : 
S2 
1, 2, 3 
3, 4, 5, 6 : l : 
Fig. 2.9 (c) Crop requirements table 
LAND UNITS 
Fig. 2.10 (c) Land unit map 
Fig. 2.10 (d) (c) overlayed with (b) 
APPENDIX 
DESCRIPTION OF THE MODULES. 
A land suitability map is constructed by using two 
kinds of data: 
a. a map description: lines, polygons, centroids; 
this description can be obtained by digitizing a 
map and assigning centroids to the contructed 
polygons; 
b. colours for the polygons (related to the 
centroids) indicating the crop (sub)classes for 
the polygon; this information is obtained by 
matching the map unit attribute table (relation 
table I, section 1) and crop requirements table 
(relation table II, section 1) and linking it with 
a colour coding table (relation table III, section 
1). 
To achieve this 7 modules are built. 
The listing of the different modules and their in- 
and outputs are shown in scheme A.l. 
A.1 MODULE MAPDIG. 
This module can be used to digitize a map on the 
Acorn BBC. For the purpose of the land suitability 
maps only lines and polygons have to be digitized 
(they may not be filled with a colour, because this 
is done in MODULE DISPL where the result maps are 
displayed). It is a less sophisticated program than 
the map digitizing program on the PDP11 and RAMTEK 
(see report TR85081). The result is an image file 
which can be stored on a diskette. 
A.2 MODULE MAPCEN. 
This module is used to classify the centroids of the 
polygons of a map. Of each polygon a centroid can be 
defined by cursor movement and after it is indicated 
its class (map unit name) must be given. The result 
is a table with the coordinates of the centroids and 
a pointer to the class name (see section 1, Table 
IV). 
A.3 MODULE ATTTAB. 
This module is used to define a table with attribute 
names and their Dossible values (see section I.a, 
attribute menu). This table is used as a menu for 
constructing a map unit table or a crop requirements 
table (see section A.4). 
This module also has the possibility to edit an 
already defined attribute table. 
A.4 MODULE MUTCRT. 
This module is used to define a map unit table (see 
section 1, relation table I) and a crop requirements 
table (see section 1, relation table II). Also 
existing tables can be edited.