Direct and residual effects of sources and levels of phosphorus and farmyard manure in maize (Zea mays)-mustard (Brassica juncea) cropping sequence

A field experiment was conducted during rainy (kharif) and winter (rabi) seasons of 2001–02 and 2002–03 to evaluate the direct and residual effects of sources and levels of phosphorus and farmyard manure (FYM) applied in maize (Zea mays L.) on the succeeding Indian mustard [Brassica juncea (L.) Czernj & Cosson]. Phosphorus application through single superphosphate (SSP) recorded the maximum grain and stover yields of maize and were on a par with that of Udaipur rock phosphate (URP) +SSP (1:1). Application of URP + phosphate-solubiliz-ing bacteria (PSB) recorded the highest available P after maize harvest. Grain and stover yields of maize significantly increased up to 60 kg P₂O₅/ha, whereas the available N and P status of the soil after maize harvest increased up to 80 kg P₂O₅/ha. FYM also significantly improved the grain and stover yields as well as the availability of N and P in the soil after maize harvest. Residual effect of P sources was found equally effective in improving the yield and nutrient uptake of mustard. Residual effect of URP+PSB recorded the highest available P in the soil after mustard harvest. Residual effect of increasing P levels up to 80 kg P₂O₅/ha significantly increased the seed and straw yields, nutrient uptake and the available N and P status of soil after mustard harvest. Residual effect of FYM also had a significant positive impact on these aspects of mustard crop as well as on the available N and P in soil.