Part V of the crop productivity model (Figure 2.1) deals with the interphase with fuelwood and livestock productivity models The interphase in essence allows the possibility of considering:
fuelwood production on land assessed as not suitable for crops in Part I of the model;
fodder from fuelwood trees for livestock production;
fallow land, defined in Part III of the model, for livestock production because of the fodder potential of fallows; and
crop residue, crop by-products and crop primary products, quantified in Part IV of the model, for livestock production.
The fuelwood productivity model is described in Technical Annex 6. It is basically a land suitability assessment model (similar to Part I of the crop productivity model) in which land potentials for individual fuelwood tree species at three levels of inputs are quantified.
Additionally, any portion of crop land may be considered for fuelwood production depending on how much land is required for crops, livestock and other land uses.
Any land which is allocated to fuelwood production with species that offer palatable fodder would have the potential for contributing a portion of the fodder for livestock production.
Fuelwood species which offer palatable fodder to livestock are listed in Technical Annex 5. The amount of fodder which can be utilized by stock without affecting fuelwood yields would depend on the species and the ecological situation. However, at this stage of the model interphase development, it is assumed that about 10% of the foliage may be utilized by stock without affecting fuelwood yields. This nominal value may be modified as appropriate according to species and environment.
It is assumed that fallow land under the low level of inputs situation would be under bush or natural grass vegetation, whereas under the intermediate and high inputs situations, fallow land would be under sown pastures.
Biomass potentials for sown or natural permanent pastures is assessed in the livestock productivity model described in Technical Annex 5.
At this stage of the model development, it is assumed, as a model variable, that the biomass potential from natural grass fallow under low inputs and the sown grass fallow under intermediate and high inputs, is one-third of that quantified for normal permanent or sown pastures. Also, it is assumed that only 50% of the biomass may be consumed by stock.
In areas with more than 120 days growing period, crop residues are an important source of fodder particularly for the low and intermediate technology livestock systems. Important residues are the haulms of the groundnut crop, cowpea and other legume crops, and the staves of sorghum, maize and millet and straw from rice, wheat, barley and oat.
Quantities of residues that may be available can be estimated by applying the residue factors and the corresponding utilization coefficients onto crop yields form Part IV of the crop productivity model. Residue factors and utilization coefficients for crops are given in Technical Annex 5.
By-products, defined as edible materials remaining after a crop has been processed, are bran, pollard and germ meal from cereal milling, molasses and bagasses from sugar milling, and cakes (cotton, soybean, groundnut) from oilseeds.
Quantities of crop by-products that may be available can be estimated by applying the by-product factors and the corresponding utilization coefficients onto crop yields. By-product factors and utilization coefficients for crops are given in Technical Annex 5.
Crop primary products apply to grain used for the purpose of feeding to animal either directly in an unprocessed form or in a processed form. Main cereals used in Kenya are maize, sorghum, wheat and barley.
Direct feeding of grain is used in cattle and goat dairy systems, and the intensive livestock industries of poultry and pig production tend to use processed feed. The amount of primary products in the livestock feed requirements for the different livestock production systems are given in Technical Annex 5.
