Integrated nutrient management in hedge lucerne (Desmanthus virgatus(L.)willed) under rainfed condition

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.