the Symposium on Wheats for More Tropical Environments - cimmyt

247program. <strong>the</strong>se diseases will not be abarrier to wheat production in <strong>the</strong>future. The severity of <strong>the</strong> rusts willincrease with increasing area underwheat production. The life span ofanyvariety under <strong>the</strong>se conditions probablywill be four to five years, which fur<strong>the</strong>remphasizes <strong>the</strong> need for a dynamicresearch program. There is no diseasedata for sprinkler-irrigated conditions;<strong>the</strong> general observations of <strong>the</strong>scientists involved are that sprinklerconditions will not change <strong>the</strong> diseasespectrum. Since <strong>the</strong> complete croppingsequence made possible by sprinklerirrigation has not been tested. diseasespeculiar to such a sequence, if <strong>the</strong>yeXist. are not yet known.Insect problems have not beenobserved. and weeds. although aproblem with summer crops, do notconstitute a problem in <strong>the</strong> winterseason.Economic ConsiderationsThe main barriers to increased wheatproduction in <strong>the</strong> Cerrados area ofBrazil will be economic ra<strong>the</strong>r thanagronomic. This is especially true ifirrigation is incorporated into <strong>the</strong>system. The cost of reclaiming onehectare of land. as of June. 1984. isshown in Table 4. As can be seen fromthis table. <strong>the</strong> irrigation cost per hectareis US$ 750 or 61 % of total cost.Without irrigation, <strong>the</strong> cost ofreclamation is only US$ 477.50, andthis would also permit <strong>the</strong> grOWing ofsummer crops, such as soybeans, riceand maize.Table 4. Average cost to reclaim one hectare of Cerrados land, with and withoutirrigation, BraZil, June 1984Cost Percent of total costReclamation needs (US$) Dryland IrrigationFertilizerLime 60 13 5Phosphorus 125 26 10Potassium 50 10 4Micronutrients 35 8 4Subtotal 270 57 23Land preparationClearing 67.5 14 5Liming 17.5 4 1Terracing 15.0 3 1O<strong>the</strong>r 7.5 1 1Subtotal 107.5 22 8Price of virgin Cerrado 100 23 8Total cost, dryland 477.5 100Cost of irrigation system 750 61Total cost with irrigation 1227.5 100Source: Goedert et al. (6)