An 8-year in-situ experiment was carried out to study spontaneous nutrient supply capacity and crop responses in vertisol,Huaibei.The data obtained indicated that,in the absence of N fertilizer,N supply capacity of vertisol declined to 64% of the original in the first investigated year,and sharply down to 22% in the second year,and then fluctuated around 20% in the years that followed.And,without P fertilizer application,P supply capacity of the soil decreased gradually throughout the 8 years of the experiment,from 95% in the first year to 45% in the last year,and so was soil 1K supply capacity,but from 90% in the first year down to 60%～70% in the 8th year of the experiment with holding K containing fertilizers1And,P and K supplying performances of vertisol,however,differed significantly from crop to crop,wheat and maize.The 8-year mean yields of wheat and maize in Treatments CK,N,NP,NK and PK were 26.9%,54.3%,85.2%,53.2%,31.8% and 21.4%,68.9%,73.5%,81.6%,28.0% of that in Treatment NPK,respectively,suggesting strong responses of the crops to fertilization models1Detailed analysis showed that,element concentrations of N and P in the seeds and straws of the crops significantly increased in the treatments with N and P fertilizer application 1K concentration in the crop's seeds,however,showed no obvious change while increased evidently in the straws in the treatments with Kfertilization.After 8 years of experiment,the total N content of the tested vertisol decreased by 5%～10% in the treatments without N fertilization,by contraries increased by 12%～16.5% in the treatments with N fertilization.And,the total P content of the soil decreased by 20% in the treatments without P fertilization,and only slightly increased in the treatments with P fertilization available.The available P content of the soil,however,varied very strongly during the experiment period,depending on P fertilization status.As for the total Kcontent of the soil,there was no obvious variation between treatments with or without Kfertilization.The content of available Kin the soil decreased by 35% in the treatments without Kfertilizer,decreased by 5.9% in Treatment NPK,and increased 10% in Treatments NK and PK1The content of soil organic matter decreased by 10% in Treatments CK and PK,and remained stable in the other treatments after the 8-year experiment.The cumulative apparent recovery rates of N,P,K fertilizers on the crops of wheat and maize were 59.8%,47.3%,50.2% and 51.1%, 33.2%,49.5% respectively during the experiment period.The equations correlation coefficients between gain and loss of soil available phosphorus and between gain and loss of soil available potassium were y(ebb and flow of soil available P)=0.113 8 x(balance of gain and loss of P)-0.406 1(n=6,r=0.959 4)and y(ebb and flow of soil available K)=0.107 5 x(balance of gain and loss of K)-8.787 1(n=6,r=0.902 1)respectively.