Effect of crop residue and farmyard manure on K forms on soils of long term fertility experiment

Incubation study of potassium was carried out on the six differentially K treated soil samples, collected from sandy loam soils of the long-term fertilizer experiment, which is in progress since 1971 in maize-wheat cropping system at Punjab Agricultural University Research farm to study the effect of crop residue and farmyard manure on K forms. The investigation was carried out in the laboratories of soil department at two temperatures (15 and 35°C) and two different rates (0.5 and 1%) of farm yard manure and rice straw was added to the soil samples. Rice straw contains higher amounts of available and water soluble K where as farmyard manure contains considerable amount of all forms of potassium. The soils showed the increase in available K status, water soluble and fixed K and maximum amount of K released at 84 days of incubation in both treatments at both the levels.