Effect of Phosphorus and Sulphur application on Forage Yield, Quality, Nutrient Uptake and Cyanide Content of Forage of Sorghum [Sorghum bicolor (L.) Moench].
Pravinchandra C. Patel, Main Forage Research Station, Anand Agricultural Univ, At and Post. Khetiwadi, Dist. Anand, Gujarat State, Anand, 388110, India
Effect of P and S on forage yield and quality has been studied in field experiments for three years on a soil, medium in P and deficient in S with forage sorghum [Sorghum bicolor (L.) Moench].The treatments were taken in combinations of 2 genotypes (GFSH-1 & SSG.59-3) and 3 levels each of P (0, 40 & 80 kg P2O5 ha-1) and S (0, 20 & 40 kg S ha-1) in split-plot design. Two cuts were harvested. The P and S applied through diammonium phosphate and gypsum, respectively. A uniform dose of N was applied with the treatments. Individually application of 80 kg P2O5 ha-1 gave significantly higher Green Forage (GF) and Dry Matter (DM) yield of forage sorghum than 40 kg P2O5 ha-1 and control (Table 1). Similarly, a level of 80 kg P2O5 ha-1 also gave significantly higher Crude Protein (CP) yield over control but it was similar with 40 kg P2O5 ha-1 (Wheeler et al., 1980 and Chand et al., 1992). Application of 40 kg and 80 Kg P2O5 ha-1 to sorghum produced 6.8 and 10.1; 9.7 and 14.4 and 4.6 and 11.6 % higher GF, DM and CP yield, respectively than control. Application of P @ 80 Kg ha-1 recorded significantly higher P uptake than control in total of two cuts. Application of 20 Kg and 40 Kg S ha-1 removed higher P uptake than control during first, second and in total of two cuts (Ahmad et al.,1995). The GF, DM and CP yield increased significantly with the individually application of 20 kg and 40 kg S ha-1over control (Table 1). Soil application of 20 Kg S ha-1 individually to sorghum significantly increased the GF, DM and CP yield to the tune of 9.4, 9.9 and 17.9 %, respectively over control. Application of 20 Kg S ha-1 to SSG 59-3 gave significantly higher DMY by 8.3 % over the highest GF yielder interaction of 20 Kg S –ha to GFSH-1.Application of 80 Kg P2O5 -ha to SSG 59-3 gave significantly higher DMY than others except 40 Kg P2O5 ha-1 to SSG 59-3.These increase was to the tune of 14.0 and 14.9 % over control. Individual application of 20 Kg S ha-1 to sorghum found advantageous for obtain higher GFY, total return and net Incremental Cost Benefit Ratio (ICBR). Plant samples were subjected to analyze for VDMD content. Combined application of 40 kg P2O5 and 20 kg S ha-1 gave significantly the highest DDM yield (65.2 q/ha).The interaction of 40 kg P2O5 and 20 kg S ha-1 to sorghum showed higher GFY with higher DDM yield and net ICBR( Singh et al., 1983). The significantly higher DMY produced by application of 20 Kg S ha-1 to SSG-59-3. The favorable points of SSG 59-3 over GFSH-1 were; 13 days earlier in maturity, thin stem and higher DM content. Considering the net ICBR, yield and forage quality production point of view, combined application of P @ 40 Kg P2O5 and S @ 20 Kg S ha-1 to sorghum gave higher GF and DDM yield as well as net ICBR. Increasing levels of P from 0 to 40 and 80 Kg ha-1 significantly reduced HCN contents of leaf by 16.0 and 18.1 %, respectively over control in first and in second cut. Similarly, HCN contents reduced in shoot and root also. Application of 40 Kg S being at par with 20 Kg S ha-1 significantly reduced the HCN contents in leaf than control in both the cuts. The lowest NDF content was found with 40 kg P2O5 ha-1 to SSG 59-3.