The purpose of this study was: (1) to assess the effect ofrnfallow perioda on the fertility of soils, (2) to evaluaternthe compounded effecta of fallow periodS and cropping yearsrnon the fertility and productivity of 80ila. Experimentsrnwere conducted on tallow-sites and on-tarU plota (previouslyrnfallowed fj,elds) to attain the above objectives. oata onrnsoil and crop oharacteristics were collected using field andrnlaboratory procedure.. The collected data were analyzedrnusing descriptive statistics and statistical methods such aarncorrelation, analysis of variance and regression.rnThe results of the experiment. on-fallow sites and on-farmrnplota indicat.e improvements in 80118 of the physical andrnchemical properties of the 80ils with increase in fallowrnperiods/years. The rates of regeneration were sorernpronounced in the earlier fallow periods and decline inrntime. However, the rates of restoration of organic'matterrnand some other evaluated nutrients on the on-farm plots werernhigher than those on-tallow s1 tes. Por example, orqanicrnmatter, total n.itroqen, calcium rates of restoration in thernon-farm plots were higher than the on-fallow sites by 8.5rnpercent, 4.3 percent , 1.6 me/l00g respectively.rnThe findinqs in the on-farm plots, reveal the combinedrneffect8 of fallow periods and cropping years on thernfertility and productivity of the soils. Por example, thernamount of increase in organic matter was predicted at 16rnpercent when the fallow period increased from the first tornthe second year, whereas it increased by only 0.5 percentrnbetween 19 and 20 years of fallow. On the contrary, organicrnmatter decreased by 12 peroent between the first and seoondrnyears of cropping and the rate of its degradation declinedrnto 2.5 percent between 10 and 11 years.rnThe increase in maize yield on the average was estimated tornbe 28 percent with every doubling in fallow period (e.g. 1,rn2, 4, 8, 16 '0' years). On annual besis this increase wasrndeclining in time. For instance, the estimated maize yieldrnincrease was as high as 28 percent between the first andrnsecond year of fallow, but this increase dropped to 4.8rnpercent between 10 and 11 years of fallow. On the otherrnhand, maize yield decreased with cultivation years. Porrninstance, the decline in maize yield varied between 20rnpercent between the first and second year of cropping andrn3.7 percent when the cropping year was 10 to 11 years.rnFrom the above, it is realized that the recurrence ofrncropping- fallow cycles (particularly if each cycle lastsrnshort duration) result in soils with low fertility andrnproductivity status. This emphasizes the very high risk ofrnsoil degradation with increasing population density andrnattendant intensity of CUltivation. The thesis at handrnsuggests some possible measures Which must be taken tornameliorate this problems.