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Grain Legumes and Green Manures for Soil Fertility in ... - cimmyt

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management operations, such as<br />

crop rotation, mulch<strong>in</strong>g, livestock<br />

:,; movements or manure transfer.<br />

Transfers will be possible between<br />

fields with<strong>in</strong> one farm, between<br />

farms, <strong>and</strong> between the farms <strong>and</strong><br />

rangel<strong>and</strong>. Different methods <strong>for</strong><br />

comb<strong>in</strong><strong>in</strong>g labour <strong>and</strong> crop /<br />

livestock models are be<strong>in</strong>g<br />

considered; one idea is <strong>for</strong><br />

management activities to be made<br />

cont<strong>in</strong>gent on there be<strong>in</strong>g sufficient<br />

available labour. The modular<br />

structure will allow different<br />

versions of submodels to be<br />

swapped <strong>in</strong> or out depend<strong>in</strong>g on<br />

the detail required.<br />

Figure 1. Resource flows with<strong>in</strong> <strong>and</strong> between heterogeneous farms<br />

complexity are however available <strong>for</strong> different<br />

flows, <strong>and</strong> ideally an appropriately complex model<br />

can be chosen <strong>for</strong> each part of the system <strong>and</strong> l<strong>in</strong>ked<br />

together where necessary to allow an <strong>in</strong>tegral<br />

analysis.<br />

A software framework (Figure 2) is be<strong>in</strong>g developed<br />

to <strong>in</strong>tegrate exist<strong>in</strong>g crop, soiC livestock <strong>and</strong><br />

bioeconomic models <strong>in</strong>to a model of the whole<br />

system. This <strong>in</strong>tegrated model will be used to<br />

explore nutrient use efficiency <strong>and</strong> labour<br />

productivity, <strong>and</strong> tradeoffs between short <strong>and</strong> long<br />

term contributions to soil fertility, <strong>in</strong> Afric\U1<br />

farm<strong>in</strong>g systems.<br />

The NUANCES framework will allow the<br />

simulation of spatially <strong>and</strong> temporally complex<br />

The aim is to create a model that can<br />

assist <strong>in</strong> <strong>in</strong>tegrat<strong>in</strong>g the expert<br />

knowledge of farmers <strong>and</strong> of scientists from<br />

different discipl<strong>in</strong>es. The modular structure will<br />

allow the pr<strong>in</strong>ciple of 'just-sufficient-complexity' to<br />

be upheld, s<strong>in</strong>ce simple models can be used <strong>for</strong><br />

whichever processes are peripheral to the parts of<br />

the system be<strong>in</strong>g considered. As well as provid<strong>in</strong>g a<br />

framework <strong>for</strong> iterative experimentation <strong>and</strong><br />

modell<strong>in</strong>g, the model will shed light on which<br />

processes most affect costs <strong>and</strong> benefits <strong>and</strong> thus<br />

allow recommendations to be better targeted.<br />

NUANCES will lead to the iterative <strong>and</strong><br />

collaborative design of more productive, susta<strong>in</strong>able<br />

systems, l<strong>in</strong>k<strong>in</strong>g directly to policy at local artd<br />

greater scales, <strong>and</strong> will facilitate the development of<br />

further rules-of-thumb <strong>for</strong> farmers.<br />

Farm (x J ",~arm rtln~')<br />

LV Uves(Qck<br />

(x 3 sizes· callie,<br />

sh""p+go.~,<br />

poUltry)<br />

P'L f<strong>in</strong>ance<br />

<strong>and</strong> Labour<br />

L T L<strong>and</strong> TyP

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