Hierarchical crop growth models can contribute signi®cantly to land quality research because the
yield gap between the estimated optimum and the actual crop production has been identi®ed as a major
land quality indicator. This study describes a three-level, hierarchical crop production model, simulating
radiation-thermal, water-limited and natural production potentials of annual crops. Input requirements have
been kept low to ensure its applicability to developing regions, which often have access only to limited data.
The simplicity of this model also has disadvantages: inconsistencies have been reported when applying this
model in semiarid regions, which are characterized by very irregular rainfall patterns. Revision of the water
balance, which simulates the availability of water, was required. The modi®ed model was validated using
the experimental yields of maize and sun¯ower in Guquka, a semiarid region of South Africa. Yields were
estimated very well, possible improvements to crop production were identi®ed and implications for land-use
planning highlighted. Yield gap analysis revealed that radiation, sunshine and temperature are favourable
for crop production, but the heavy dependence on rainfall makes the region very vulnerable to drought,
with devastating impact on yields. The generally low chemical soil fertility further reduces crop performance.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:tut/oai:encore.tut.ac.za:d1000885 |
| Date | January 2003 |
| Creators | Van Averbeke, W, Verdoodt, A, Ranst, E |
| Publisher | Soil Use and Management |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | |
| Rights | Soil Use and Management |
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