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 [Brassicajuncea (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:l). Application of URP + phosphate-solubiliz- ing bacteria (PSB) recorded the highest available P after maize harvest. Grain and stover yields of maize signifi- cantly increased up to 60 kg P,O,/ha, whereas the available N and P status of the soil after maize harvest in- creased up to 80 kg P,O$ha. FYM also significantly improved the grain and stover yields as well as the availabil- ity of N and P in the soil after maize harvest. Residual effect of P sources was found equally effective in improv- ing the yield and nutrient uptake of mustard. Residual effect of URP+PSB recorded the highest available P in the soil after mustard harvest. Residual effect of increasing P levels up to 80 kg P,O$ha significantly increased the seed and straw yields, nutrient uptake and the available N and P status of soil after mustard harvest. Residual ef- fect 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.