Restoring the Soil - Canadian Foodgrains Bank

58Green Manure/Cover Crop Systems30. Honduras. This photo is not of a handful ofcompost, though it may seem like it is. This isthe soil of a typical field in the maize/mucuna-1system, after planting maize every year for 40years. Without the mucuna in this poor tropical soil,a farmer can grow maize for three to four years,and then will have to fallow it for ten to twelveyears. By using mucuna (which can be seen inthe background of the photo), farmers can plantmaize every single year with no loss in productivity.Instead, production gradually increases, up to apoint of diminishing returns at which maize yieldsare about 35% less than those produced on thelower-elevation flatlands using hybrids, irrigation,plows, etc.. However, even though the productivityis lower, the total cost per ton produced is about30% lower than in the conventional system,because the expenses are so much lower. Thus,the maize/mucuna system provides a much largerprofit while operating on less valuable land andincreasing the productivity of that land from yearto year.S2. Maize/mucuna-2. This system is usedwest and south of the maize/mucuna-1system, where there is less rainfall and adry season occurs from December throughApril. It is used on irrigated land, with themucuna intercropped among the maize 30to 40 days after the maize is planted. Theearlier planting increases the danger of themucuna choking out the maize, but thelater dates reduce the organic matter thatthe mucuna will eventually produce. Oftenone pruning is needed to keep the mucunafrom covering the maize, although thiswill depend on the height of the maize,how many months the maize requires tomature, etc.. Different planting patternsare used; one is to plant three seeds per hillof maize, but only in every other row. Theplanting seasons depend on the supplyof irrigation water. This system seems toonly be used by a few hundred farmers inMexico, and a few others in Costa Rica.This system is probably an adaptation ofmaize/mucuna-1 developed by farmersthemselves for use in lower-rainfall areas.S3. Maize/jackbean. Jackbean (Canavaliaensiformis) is intercropped with maize ina number of areas of northern Yucatanand the state of Oaxaca. The jackbean isplanted at the same time as the maize, withtwo or three seeds per square metre, orsometimes four if the weeds are particularlyproblematic. Sword beans (Canavaliagladiatus) can be used in place of thejackbean. In Brazil, both jackbean and C.paraguayensis are intercropped with maize. Thousands of farmers in both Mexico andBrazil use this traditional system. For this system, use only the bushy-type jackbean,not the climbing type.S4. Maize/lima bean. Lima beans (Phaseolus lunatus), locally called “ibes,” are intercroppedwith maize on the Yucatan Peninsula. The beans produced are, of course,eaten. The lima beans are planted either together with the maize or up to a monthafterwards. Tens of thousands of farmers are using this traditional system. A similarsystem is used in western Guatemala (where the lima bean is called “piligua”) andsouthern Honduras (where it is called “chilipuca”).