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Crop Yield Forecasting

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The stratification classes used are the following:<br />

Agriculture classes:<br />

1. Cultivated greater than 80 percent<br />

2. Cultivated between 30 and 80 percent<br />

3. Cultivated 1 to 30 percent<br />

4. Irrigation schemes<br />

5. Non-commercial/communal area<br />

6. Sugarcane<br />

7. Horticulture/viticulture<br />

8. Plantations<br />

9. Smallholdings/peri-urban<br />

10. Rangeland<br />

11. Rangeland<br />

Non-agriculture classes:<br />

12. Urban (residential/commercial – no cultivation)<br />

13. Conservation, mines & rock (national parks, mines, bare rock)<br />

14. Water bodies<br />

Classes 6 to 9 are collapsed into a single class to reduce the number of sample points<br />

required for classes in which the probability of finding cultivation of grain crops of interest<br />

is low. The collapsed stratum is then sampled. The non-agricultural classes (12 to 14) are<br />

not sampled because the probability of finding the crops of interest therein is very low or<br />

negligible.<br />

FIGURE 4.4<br />

Stratification for summer crops<br />

The summer crops are stratified in high, medium and low strata based on field densities in a 5 km x 5<br />

km grid. The stratification is used to guide the distribution and location of the field sample points, and<br />

thus to improve the overall statistical representation.<br />

<strong>Crop</strong> <strong>Yield</strong> <strong>Forecasting</strong>: Methodological and Institutional Aspects 125

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