Available Phosphorus and Potassium and Soil Organic Matter Contents as Influenced by Long Term Application of Fertilizers and Farmyard Manure to Wheat-Maize Rotation

The effect of phosphatic and potassic fertilizers and farmyard manure (FYM) application to wheat-maize rotation for 9 years, was studied on some properties of a Choa sandy loam soil. The 12 treatments comprised two rates of FYM, three doses of P, and two of K applied to maize or wheat alone or to both the crops. Farmyard manure significantly increased organic carbon and available P and K status of the soil. Phosphorus treatments increased available P only in combination with FYM whereas potassium fertilizer did not influence available K level of the soil. Contents of organic C, available P and K were significantly higher when both the crops were fertilized. However, interaction of treatments with season of fertilizer application indicated that it was only FYM addition to both the crops which resulted in higher values.