Fertility Status of a Tolewal Loamy Sand after Six Years of its Use under Nine Multiple Cropping Systems

Surface soil samples collected at the start and after 6 years of growing various cereal, pulse, oilseed and tuber crops in nine different fixed crop rotations were analysed for pH, electrical conductivity, organic carbon, available nitrogen, phosphorus and potassium, total nitrogen and cation exchange capacity. The available nutrients increased proportionately with the total amount of N, P and K applied through fertilizers. Differences in the amount of applied nutrients and those removed by the crops per year correlated significantly with the available nutrients in the soil, indicating recyclying of N and K from the sub-surface soil layers to the surface layer through growing of the crops. Total nitrogen and organic carbon also registered an increase over the values at the start of the experiment. The treatments did not affect soil pH. High values of electrical conductivity were obtained in soil samples from rotations having maize fodder as the summer crop. Cation exchange capacity decreased with increasing application of fertilizer potassium.