Effect of phosphorus, irrigation and Rhizobium on productivity, water use and nutrient uptake in fenugreek (Trigonella foenum-graecum)

An experiment was conducted during winter season of 2001–2004 for consecutive 3 years at Sriganganagar in Rajasthan to study the effect of phosphorus, irrigation and Rhizobium inoculation on seed, economics, water use and nutrient uptake of fenugreek (Trigonella foneum-graecum L.). Application of 40 kg P₂O₅/ha significantly increased the yield attributes, viz. branches/plant, pods/plant, pod length, seeds/pod and test weight and finally the yield (8.08 q/ha) over 20 kg P₂O₅. Phosphorus @ 40 kg P₂O₅/ha gave the highest mean benefit: cost ratio (1.47) in comparison with 20 (1.38) and 60 kg P₂O₅/ha (1.42). The highest P-use efficiency (35.95 kg/kg P₂O₅) was recorded at 20 kg P₂O₅/ha, and further increase in P decreased the P-use efficiency. An increase m P level, increased the consumptive use but had no effect on water-use efficiency. Highest level of P₂O₅ led to greater extraction of moisture from lower depth of rhizosphere. Application of P increased the N, P and K uptake up to 40 kg P₂O₅/ha. IW:CPE ratio of 0.8 significantly increased the yield (10.20 q/ha), benefit: cost ratio (1.81), consumptive water use (291.9 mm) and nutrient uptake compared to IW: CPE ratio of 0.4 and 0.6. Higher yield attributes as well as higher seed (8.14 q/ha) and stover yields (17.36 q/ha) were recorded with Rhizobium inoculation than with uninoculated crop. Higher water use (244.8 mm), water-use efficiency (3.2 kg/ha-mm) and nutrient uptake (N 31.6, P 5.5 and K 37.9 kg/ha) were also recorded with the inoculated crop.