Effect of nitrogen and potassium fertilization on herbage yield of Cenchrus ciliaris+Stylosanthes hamata mixed pasture and soil fertility.

摘要

A field experiment was conducted at the CR farm of IGFRI, Jhansi, Uttar Pradesh, India, during 1997-2000 with N (0 and 40 kg/ha as urea, and 20 kg/ha urea + 20 kg/ha FYM slurry) and K levels (0, 40, 80 and 120 kg K2O/ha) to determine the effect on herbage yield of Cenchrus ciliaris + Stylosanthes hamata mixed pasture and soil fertility including microbial health of the system in terms of soil microflora, soil microbial biomass and activity. The results showed that the higher herbage yield of C. ciliaris + S. hamata was recorded at 7-21% with K (40-120 kg K2O/ha) and 14-20% with N application (40 kg/ha) alone over control. The application further increased herbage yields and the maximum (33.5-42.5%) was reached with combined dose of K plus 20 kg N/ha as urea and 20 kg N/ha as FYM slurry. The uptake of K improved by 11-35% with K levels and by 16-27% with N levels. The increase in K uptake was 38-72% with full dose of urea (20 kg/ha) and K levels (40-120 kg K2O/ha) and 55-84% with half dose of N as urea (20 kg/ha), and the rest half dose of N of N (20 kg/ha) and half dose of N (20 kg/ha) through FYM slurry with K levels (40-120 kg K2O/ha) over control. N uptake was higher by 13.4-33.2% with K application and 28.1-34.8% with N application alone. The percent increase in N uptake of 54.2-71.5 was highest with combined dose of N half as urea (20 kg/ha) and half dose of FYM slurry (20 kg/ha) along with K levels of 40-120 kg/ha over control. However, the herbage yield and nutrients removal was significantly higher with 80 kg/ha in the presence of 20 kg N/ha each through urea and FYM slurry. The soil fertility in terms of increasing available K and N, organic carbon and porosity, and decreasing bulk density was maximum with combined dose of 120 kg K2O/ha and 20 kg N/ha each through urea and FYM slurry. The microbial biomass (474.4 mg/kg soil), respiration (213.5 mg CO2-C/kg soil) and fungi counts (15.5x104) were maximum under N application of 20 kg/ha each through urea and FYM slurry along with 120 kg K2O/ha. But the highest bacteria (14.2x106) and actinomycetes (18.1x105) was noted when 40 kg/ha through urea and 120 kg K2O/ha were applied..