Crop simulation models and some implications for agroforestry systems

ICRISATs work on nlodeling sosorghrrm, pearl millet, and groundnrrt is summarize4 and flle inlplications foragroforeshysystems an mmined. Trees can improve waterinjiltration and ufiliied eeprpmjile water not accrssible to con~mtionalc rops. In thispaper we have shrdied how the bttroduction of tree species in crop systenls m,ottld affect overall water use a~~dproditctivitIV).e haw analp-d climatic data ojfive selecfed locations in arid and semi-arid India in terms oJt1te distribution and dependability ofrainfoll and the trend in seasonal rainJatlpatten1 in the recent years. Pmbabililies oJavailable soil water are simlrlated for these locations. Available waler holdi~tgcapacityo fthesoils are assumedas 25,50,100, and l5Omm at each oftheselected locations to accortnt soilsfor ratcging from very shallow lo medirrm deep. Grain yields and total drynratterare si~nrtlatedfort hese agroclimatic conditions to outline the environmeqts where agroloresty is feasible. Grain yields and total dry matter oJtlte crops at various le~*elosf shading by the treeconlponent are sintrrlated. =se results are qected to giw some insight as to how the tree-ntanagement will am1 the microclintale and productivity of the crop. Effects of changes in niicroclimale such as canopy temperature and radiation intercepted (by manipnlatbrgrow widrh, plant dettsir);canopygrowrhJ on productivity based on information from intercroppC~gandJorestystudiesa rediscussed Simulation mulfsarec ornpared wit11 tlte crperintental data from ICRlSAT and elsewhere on appropriate cropping systems under various agroclimatic conditions. hfinimunt data sets that need to br coNecledfrom specijc qerimcnfs designed for agrajoresty sfudies are identified