Restoring the Soil - Canadian Foodgrains Bank

Using The Decision Tree276. Using The Decision TreeHow to Use the Decision TreeThe following decision tree should not be seen as a straitjacket. It should be used toget new ideas, but not to restrict what you can do. The options given may be expandedon. Other species can be tried. That said, the gm/cc systems listed in this decisiontree are definitely worth a try. Nearly all of them are proven systems that hundreds offarmers have used for years, usually in the absence of any outside program. In manycases, thousands of farmers have used them for centuries.Green Manure/Cover Crop Systems Included in the Decision TreeThe gm/cc systems included in this decision tree are almost all systems that either I orGabino Lopez, a Guatemalan colleague, have observed during our more than 25 yearsof observing gm/cc systems around the world. Thus we know the systems, have a feelfor the situations in which they have prospered, and have been able to interview farmersusing these systems. The list includes systems that are used in about 25 developingcountries. Obviously, there must be many systems that we have not observed inthese countries, and additional systems most likely exist in approximately another 60developing countries.This list includes only gm/cc systems that use legumes. It does not include nonleguminousgm/ccs such as the oats, forage turnip (Raphanus sativa) and sunflowersoften used in South America, the fonio used in West Africa or the three-year cassavaused in Vietnam. It also does not include the vast majority of gm/cc systems based ontree species in agro-forestry systems, which are also extremely common around thedeveloping world. 12 In most cases, the number of farmers mentioned is only a roughestimate, since it has often been 10 to 20 years since Gabino or I visited these systems.The gm/cc systems are distinguished from each other by the species of gm/cc thatis used, by the cash or subsistence crop, or by the date of planting or managementof each system. When essentially the same gm/cc system is used in more than onecountry or continent, I will describe the system only once and list the other places it ispracticed. In many cases, especially when gm/ccs are used in rotations or to recuperatewastelands, they are associated with any of a number of traditional crops. In thesecases, each gm/cc species is counted as one system.Characteristics of the Green Manure/Cover Crop Systems RecommendedAs mentioned, the gm/cc systems included in this decision tree are those that haveproven themselves most successful among smallholder farmers, according to twocriteria. The first is that their use has spread fairly widely. A particularly dramatic casewould be that of S1, the maize/mucuna system in Mexico and Central America,12Cairns, Malcolm, ed., Voices from the Forest, Integrating Indigenous Knowledge into Sustainable Upland Farming (Washington,D.C.: Resources for the Future, 2007).