Effect of Manures and Phosphorus on Yield and Quality under Rice-Blackgram Cropping Sequence

A field experiment was conducted on phosphorus dynamics in relation to nutrient management in rice- blackgram cropping sequence with respect to yield and quality as influenced by effect of organic manures and inorganic phosphorus at Agricultural College Farm, Bapatla. The results revealed that grain yield of rice was significantly higher with the application of 100% RDNK in combination with Dhaincha @10t ha-1 (M3) and it was on par with that of application of RDNK along with sunhemp @10t ha-1 (M2). However significantly lower was recorded in RDNK alone (M0) during both the years of the study. Among the P levels, the treatment P5 (120 kg P2O5 ha-1) recorded significantly highest grain yield and it was on par with P4 (90 kg P2O5 ha-1) and P3 (60 kg P2O5 ha-1) and lowest was recorded in P1 (0 kg P2O5 ha-1). In succeeding blackgram seed yield was significantly influenced by the organic manures and phosphorus levels imposed to preceding rice crop. The seed yield was significantly higher with the application of 100% RDNK in combination with Dhaincha @10t ha-1 (M3) and it was on par with that of application of RDNK along with sunhemp @10t ha-1 (M2) and RDNK+ FYM @ 5t ha-1 (M1). However significantly lower was recorded in RDNK alone (M0) during both the years of the study. Among the P levels, the treatment P4 (90 kg P2O5 ha-1) recorded significantly highest seed yield and it was on par with P5 (120 kg P2O5 ha-1), P3 (60 kg P2O5 ha-1) and P2 (30 kg P2O5 ha-1), while lowest was recorded in P1 (0 kg P2O5 ha-1). Regarding quality parameters of rice grain viz., amylose and protein were recoeded significantly higher in RDNK+Dhaincha @10t ha-1 (M3) and this was on par with that of application of RDNK along with sunhemp @10t ha-1 (M2), while M2 was remain on par with RDNK+ FYM @ 5t ha-1 (M1). Among the P levels, the treatment P5 (23.86 and 24.71%) registered significantly higher amylose content and lower was registered in P1 (21.59 and 22.43%). However, protein content was slightly increased from 0 to 120 kg P2O5 ha-1 but not significantly differed. Similarly the data regarding influence of organics and P levels applied to preceeding rice crop on protein content of succeeding blackgram followed same trend as in rice.