Restoring the Soil - Canadian Foodgrains Bank

Choosing The Right GM/CC Cropping System For A Specific Area23then leave it growing through the dry season after the traditional crop is harvested.An example of this method is S7, the maize/sweet clover system in Mexico.e) The gm/cc can be grown under fruit or forest trees or almost any perennialcrops. In this case, we choose particularly shade-resistant gm/ccs, like jackbeans orCentrosema pubescens.f) Occasionally we can use other ways of growing gm/ccs without affecting themain crop. These include growing gm/ccs during periods of frost (lupines, such astarwi, often do well), in soils that are too acidic for our crops (mucuna or buckwheat),or during very short periods of time (as in the case of Sesbania rostrata).2. Gm/ccs must not cost money. This rule implies that farmers must be able to producetheir own gm/cc seed year after year, and that the gm/ccs must have no diseaseor insect problems that are serious enough to significantly diminish their growth.Insect attacks that do not affect the growth of the plants are fine; they merely helpprocess the organic matter. If an insect or disease problem does significantly reduce agm/cc’s growth, we must usually discard that species and start using another one. TheBrazilians, for instance, quit using lablab beans some 20 years ago because it was tooheavily attacked by insects. This rule also means we cannot use inoculants (commercialproducts that increase the fixation of nitrogen).3. Gm/ccs must not increase labor costs very much. This rule means that, exceptwhere animal traction or tractors are being used, gm/ccs will have to be left on the soilsurface. It also means that the intercropping of gm/ccs is particularly advantageous,because the weed control the gm/cc provides when it is intercropped can often savemore labor than the labor needed for planting and cutting down the gm/cc.The labor problem is also the main reason why farmers appreciate zero till systems.Farmers will often decide to plant gm/ccs primarily because of the hope that they willnever again have to plow or hoe their fields. Since farmers must maintain high levelsof organic matter in the soil in order to be able to use a zero till system indefinitely,this desire to eliminate the plow or the hoe is a motivating factor for the long-term useof gm/ccs.4. Gm/ccs must fit into the existing farming systems. Gm/ccs will be seen as muchless important than food or cash crops, at least for the first few years. Thus farmersand extension workers have to adjust the gm/cc to fit into the already-existing croppingsystem, rather than adjust the farming system to fit some way of growing a gm/cc.5. The gm/cc should provide at least one important benefit in addition to improvingthe soil. In a worldwide study of gm/cc systems that were taught to farmers throughprograms, almost all of the gm/cc systems that persisted after the development organizationhad left the area were those systems that produced important benefits aboveand beyond soil improvement. Thus, whenever possible, we should promote gm/cc