An experiment on indian mustard was conducted during 1999-2001 to study the effect of 3 irrigation levels based on the ratio of irrigation water depth: cumulative pan evaporation (IW : CPE) and 4 sulphur levels [(Brassicajuncea (L.) Czernj. & Coson at Pusa, Bihar. The seed yield increased significantly up to an IW : CPE ratio of 0.8 (1.59 tonnes/ha) with 2 irrigations each of 5 cm depth. However water-use efficiency was higher at 0.4 ratio with 1 irrigation. Response to sulphur was recorded up to 30 kg S/ha which was at par both with 15 and 45 kg S/ha. Plant height, dry matter/plant and length of siliqua increased significantly up to 0.4 IW : CPE ratio and 15 kg S/ha. Total sulphur uptake was highest at 0.8 IW: CPE ratio, whereas significant increase in net returns was only up to 0:4 ratio and 15 kg S/ha. Soil-moisture depletion was higher from 0-60 cm layer with 2 irrigation, whereas relative depletion in lower soil profile (60-90 cm) was more in rainfed control.

An experiment was conducted to stud9 the influence of irrigation and nitrogen on oil (%) and seed yield of Arun Hybrid of sunflower (Helianthus annuus L.). Significant increase in yield (1 7.4 and 18.0: qlha) was recorded up to 3 irrigations with IW : CPE ratio of 0.8. Oil yield and net returns were also maximum at this level. The crop showed significant response up fa 40 kg Nlha. The leaf area index and other ancillary characters were also maximum in case of 3 irrigations and 40 kg Nlha. Oil (%) and water use efficiency were higher at 1 irrigation but from the economic point of view, 3 irrigations resulted in more net returns. Soil moisture depletion in 0 60 cm layer was higher than that in 60 90 cm soil layer, but the relative depletion in 60 90 cm layer was more in rainfed due to penetration of roots in search of soil moisture.

In a 2-year study at Pusa, maximum average yield (2.81 qlha) of summer sesame (Sesamum indicum L.) was recorded with 3 imgations each of 6 cm at IW : CPE of 0.7. Further reduction in frequency of irrigation to 1 or 2 based on IW : CPE or days after sowing resulted in a significant reduction in seed yield. The yield was minimum (1.78 qha) under the rainfed control. Among levels of nitrogen, significant increase in yield was recorded up to 90 kg Nha (2.61 qha). A significant increase in leaf-area index (LAI), number of capsuleslplant and 1,000-grain weight was recorded up to 2 irrigation. For LA1 response to nitrogen was noticed up to 90 kg Nha, whereas for number of capsuled plant and 1,000-seed weight increased only up to 30 kg Nha. Maximum oil (%) was recorded with 2 irrigations and at 30 kg Nlha. Higher N levels depressed oil (%) in sesame. Nitrogen uptake by plants increased significantly up to 3 imgations and 90 kg Nlha. A major part of soil-moisture depletion was recorded froin 0-60 cm profile layer. In deeper layer (60-90 cm) depletion was more in drier regimes than in wet ones.

A field experiment with 3 levels of water management practices (rainfed with and without drainage, and irrigation with drainage) and 5 cropping systems -maize (Zea mays L.), groundnut (Arachis hypogaea L.), turmeric (Curcuma Jonga L), maize +turmeric ana maize + groundnut was conducted during rainy season of 1990-92. Leaf area index and dry-matter production of all the crops were maximum under irrigation and proper drainage system, Maize-equivalent yield was Significantly highest (8,2 tonnes/ha) in case of maize + tunneric as compared to sole crops as well as maize +groundnut intercropping system during first year. However, during second year, difference between maize + turmeric and maize + groundnut system was not pronounced. Net return during first year did not differ between maize + groundnut and maize + turmeric but during second year maize + groundnut excelled in net return as compared to maize + turmeric.Irrigation with drainage provision resulted in maximum yield equivalence (7.5 tonnes/ha) and net return (Rs 11 752)as compared to other treatments. The water-use efficiency was maximum in case of pure crop of turmeric (0.499 tonne/ha/cm) while in second year it was maximum (0.583 tonne/ha/cm) under sale crop of groundnut.

A field experiment was conducted during 1994-95 to 1996-97 to study the effect of Zn on cane population and yield of sugarcane (Saccharum officinarum L.) in calcareous soil. The maximum final stalk number was produced by basal application of 10 kg Znlha. Its splitting could not bring marked effect. The highest cane yield was also owing to basal application of 10 kg Znlha but was at par yith that of its 2 or 3 splits during first 2 years where 1 split was given at the time of planting. Foliar spray did not improve cane yield in the first year, but 0.1% in the .- second year and 0.2% in the third year gave significantly higher yield than control. - Key words : Zn, Tillering, Calcareous soil, Sugarcane

An experiment on summer sunflower (Helianthus annuus L.) was conducted during 1994-96 with 4 irrigation levels based on the ratio of irrigation water depth : cumulative pan evaporation (IW : CPE) and 4 nitrogen levels in Bihar. The results showed that seed yield increased significantly at IW : CPE ratio of 0.8 (1.49 tonnes/ha) with 6 cm depth comprising of 6 irrigation. But water-use efficiency was higher at 0.6 ratio with 4 irrigation. Response to nitrogen was recorded only up to 40 kg N/ha. Plant height, dry-matter/plant and capitulum diameter were maximum at 0.8 IW : CPE ratio. But 1000-seed weight increased only at IW : CPE of 0.6 and 40 kg N/ha. Total nitrogen uptake and net return were also highest at 0.8 IW : CPE ratio and 40 kg N/ha. Soil-moisture depletion was higher from 0-60 m layer with 4-6 irrigation, whereas relative depletion in lower soil profile (60-90 cm) was more in rainfed control.

A field experiment was conducted during 1992-93 and 1993-94 to study the effect of preceding rainy-season (kharif) crops on nitrogen requirement of wheat (Triticum aestivum L, emend. Fiori & Paol.), The optimum dose of N for wheat was lowest (91.6 kg/ha) when it was grown after green-manure crop dhaincha [Sesbania cannabina (Retz.) Pers.], with corresponding economic yield of 46.9 q/ha. When wheat was grown after blackgram (Phaseolus mungo L.) the optimum dose of N was found to be 121.0 kg/ha, with wheat yield of 43,6 q/ha which was the second lowest after dhaincha-wheat sequence. Response of wheat to N was also found maximum in dhaincha-wheat sequence (26.82 q/ha) and lowest in rice-wheat and fodder sorghum [Sorghum bicolor (L.) Monech]-wheat sequence.

A field experiment was conducted on french bean (Phaseolus vulgaris L.) with 6 levels of irrigation and 3 levels of nitrogen during the winter season of 1991-93 at Pusa. Leaf-area index and dry-matter production were maximum at 3 irrigations, 0.8 IW: CPE (IW, Irrigation water; CPE, cumulative pan evaporation) ratio and 120 kg N/ha. Grain yield and net returns were highest with 0.8 IW : CPE ratio, 3 irrigations and 120 kg N/ha. Water-use efficiency was maximum with 1 irrigation. Soil-moisture depletion was higher from 0-60 em layer with 2-3 irrigations, whereas relative depletion in the lower soil profile (60-90 em) was more with 1 'irrigation.Total N uptake increased significantly with increase in the levels of irrigation and nitrogen.

A field experiment was conducted at Pusa (Bihar) during the winter season (rabi) of 1991-92 and 1992-93, to study the response of irrigation and nitrogen fertilization on French bean (Phaseolus vulgaris L.). Significant increase in seed yield was recorded with 3 irrigations in both the years. During the first year, it was maximum when irrigation was applied on days interval basis, while during second year an at IW : CPE ratio of 0.8. The difference between 2 and 3 irrigations applied through both the approaches was not significant in the second year. Growth and yield attributes were maximum under 2-3 irrigations, whereas water-use efficiency was maximum with 1 irrigation. Inconsistent results were observed for plant height, branches and leaves/plant with 80 and 120 kg N/ha during both the years. There was a linear increase. in Seed yield and pods/plant due to increase in N level from 40 to 120 kg/ha. Seeds/pod and test weight increased significantly up to 80 kg N/ha.

An experiment was conducted during 1987-90 with 5 irrigation treatments based on irrigation water depth : cumulative pan evaporation (IW : CPE) ratios with sole crops of maize (Zea mays L.) and potato (Solanum tuberosum L.) and their intercropping. In maize alone, maize-equivalent yield was maximum (5.38 tonnes/ha) at an IW : CPE ratio of 1.0, whereas in sole potato and in its intercropping with maize a significant increase(11.25 and 13.34 tonnes/ha respectively) was recorded up to an IW : CPE ratio of 1.2. Net return was maximum up to an IW : CPE ratio of 1.0 in sole crops of maize (Rs 6937/ha) and potato (Rs 12684/ha), whereas in intercropping stands maximum (Rs 15398/ha) net return occurred at an IW : CPE ratio of 1.2 with 7 irrigations. Water-use efficiency was maximum at an IW : CPE ratio of 0.8 in sole crops of maize and potato, and at 0.6 in the mixed crops. Soil-moisture depletion was more (42.22 mm at 1.2 ratio) from the 0-60 cm layer in the intercropped than that in pure crop of either maize (32.25 mm at 1.2 ratio) or potato (13.89 mm at 1.2 ratio).

In a 4-year field experiment at Pusa (Bihar). late-sown lentil (Lens culinaris Medikus) gave maximum grain yield (1 598 kg/ha) with 3 irrigations scheduled through an 1W : CPE (irrigation water depth : cumulative pan evaporation) ratio of 0.6 with a total irrigation requirement of 12 cm. Further increase in irrigation to 3 gave similar yield but I irrigation significantly reduced the yield, The minimum yield was recorded in the rainfed control. Among levels of P. the yield increased only up to 12.9 kg P/ha. The interaction between irrigation and P was absent. A significant increase in crop-growth rate was recorded up to 2 irrigations and 12.9 kg P/ha. Profile-moisture use by the crop was maximum in 0-30 cm layer than at lower depths. In irrigation and in rainfed more water was extracted from the lowermost profile (60-90cm). The uptake of P increased up to 3 irrigations and 12.9 kp P/ha.

An experiment was conducted during 1986-87 and 1987-88 at Pusa to evaluate the irrigation requirements of different rice (Oryza sativa L.)-based crop sequences. There was a positive gain in nitrogen and potassium in all the crop sequences at different levels of winter and summer irrigations but phosphorus balance was negative. Maximum nitrogen balance was recorded under rice-gram (Cicer arietinum L.)-greengram (Phaseolus radiatus L.) (128 kg N/ha) cropping sequence, whereas maximum potassium balance was under rice-maize (Zea mays L.)-blackgram (P. mungo L.) (184 kg K/ha). Phosphorus-balance sheet showed a loss in all the crop sequences. Maximum loss of phosphorus was recorded under rice-potato (Solanum tuberosum L.)-greengram (-214 kg P/ha) sequence.

An experiment was conducted during 1986-87 and 1987-88 at Pusa to evaluate irrigation requirements of different rice (Oryza sativa L.)-based crop sequences. A significant variation in yield equivalence (in terms of rice) and net return due to different crop sequences was observed. Maximum yield equivalence (145.66 and 159.46 q/ha) was recorded in rice-potato (Solanum tuberosum L.)-greengram (Phaseolus radiatus L.) sequence, with a net profit of Rs 15,534 and Rs 18,193/ha during first and second years respectively. This value was recorded when irrigation was scheduled with 3 days disappearance of ponded water in rice, 1.2 IW: CPE ratio in potato and 2 irrigations at 20 and 40 days after sowing in greengram with a total quantity of 131.80 and 140.81 cm/ha of water in all 3 crops of the sequence. Maximum quantity of water (145.80 and 188.55 cm/ha) was required by rice-maize (Zea mays)-blackgram (Phaseolus mungo L.) but the income was less than former sequence, though it was higher than remaining 3 sequences. Minimum yield equivalence (66.93 and 77.88 q/ha) and net profit (Rs 7,971 and Rs 10,198/ha) were recorded in rice-chickpea (Cicer arietinum L.)-greengram sequence. Water-use efficiency was also higher in rice-potato-greengram (110.51 and 113.24 kg ha-cm) than others.