Abstract:
A field experiment was conducted at the Instructional Farm, College of
Agriculture, Vellayani, Thiruvananthapuram, Kerala State to find out an integrated
nutrient management technique for Desmanthus virgatus (L.) Willd. under rainfed
condition. The influence of chemical fertilizers and biofertilizers on growth
parameters, fodder yield, quality of produce, uptake of nutrients, chemical properties
of soil and economics was investigated.
Three levels of nitrogen (0, 15, 30 kg N ha"), three levels of potassium (0, 20,
40 kg ha") and biofertilizers (Rhizobium, AMF and Rhizobium + AMF) were
combined to form twenty seven treatment combinations. The experiment was laid out
in split plot design with three replications.
Results of the experiment revealed that the chemical fertilizers as well as
bioinoculants had significant positive influence on improving the fodder production
potential of Desmanthus virgatus. Application of inorganic fertilizers and eo-
inoculation of hedge lucerne with Rhizobium and AMF significantly increased the
growth parameters namely plant height, length of branches, number of branches and
leaf: stem ratio.
Highest dose of chemical fertilizers and dual inoculation with biofertilizers
registered maximum green fodder yield in all four harvests. Similar results were
obtained in the case of dry fodder yield also.
Quality parameters of the forage significantly improved as a result of dual
inoculation with biofertilizers. Maximum crude protein content was realized with
application of highest dose of nitrogen and potassium.
The nutrient uptake showed a significant increase with increase in doses of
chemical fertilizers. Dual inoculation of biofertilizers significantly increased the
uptake of nitrogen, phosphorus and potassium.
Combined application of biofertilizers improved the nitrogen and phosphorus
status of the soil after the experiment. Highest dose of nitrogen gave the highest soil
nitrogen content. Similarly highest dose of potassium recorded highest soil potassium
content after the experiment.
The physical and economic optimum dose of nitrogen for Desmanthus
virgatus was 32 kg ha-I and 31 kg ha-I respectively while that of potassium was 22 kg
ha-I, The use of chemical fertilizers and dual inoculation with biofertilizers recorded
highest net returns and benefit: cost ratio, emphasizing the need for an integrated
approach in nutrient management.
