4. 100yo of the available moisture No irrigation. 14

rrigation SOL MOSTURE REGMES AND LEVELS OF NTROGEN: EFFECTS ON THE YELD AND QUALTY OF SUGARCANE P. P. Singh and Govindra Singh U.P. Agricultural University Pantnagar, Nainital, U.P., ndia ABSTRACT A field experiment was conducted to study the effects of soil moisture and nitrogen levels on the yield and quality of sugarcane at the U.P. Agricultural University, Pantnagar (Nainital) during 1968-69. rrigations were applied when 25, 50, 75 and 100% available soil moisture was depleted during the pre-monsoon period. The treatments of 50, 75 and 100% depletion and no irrigation were superimposed over these treatments during the post-monsoon season. The levels of N were 75, 150, 225 and 300 kg/ha. The variety selected for the study was Co 1158. The study revealed that soil moisture regimes and N applications significantly influenced the cane yield and available sugar/ha. rrigation at 75% depletion of available moisture during the pre-monsoon period gave the highest cane yield of 102 tons/ha, which was significantly more than that of the 100% depletion treatment. This regime also produced a significantly higher amount of available sugar (110.99 ton)/ha over all other regimes. A dose of 150 kg N/ha gave the highest cane yield of 98.62 ton/ha, which was significantly more than that of the no N application. The interaction between soil moisture and N was found to be significant with respect to cane yield. The highest cane yield of 107.72 ton/ha was obtained under the 75% depletion treatment during the pre-monsoon period with 150 kg N/ha. NTRODUCTON The yield and quality of sugarcane are closely related to the amount of N applied and the availability of soil moisture in the root zone. Hence, it is necessary to work out the optimum level of N and suitable moisture level. rrigation experiments conducted so far in ndia on the sugarcane crop were based mostly on the depth, delta and interval. There is little work done on the basis of soil moisture regimes. Narasimha Rao and Satyanarayanan (1960) reported that irrigation at 50y0 availyble moisture gave higher sugarcane yields than 14% available moisture in the soil. Singh et al. (1960), Choudhury (1961) and Bhoj (1962) reported that increasing levels of soil moisture in the pre-monsoon period increased the stalk' length and yield of sugarcane. Varma (1965) stated that tillering in sugarcane increased with increasing soil moisture availability. Cheema and Moolani (1968) stated that irrigation at lower tension on the basis of 50% depletion of availablk moisture significantly increased growth and length of millable cane over the driest regime of 90% depletion. They have also reported that tillering increased ifth increasing soil moisture availability. Narasimha R ~ O (1969) reported that irrigation at 25y0 available moisture gave the highest cane

854 RRGATON yield, followed very closely by 50y0. Yield was significantly lowered at 75Vo available moisture loss. He did not observe any reduction in juice quality by irrigating cane more frequently. However, the best soil moisture regime reported by Cheema and Moolani (1970) in relation to cane yield was 50% depletion of available soil moisture. Very few scientists have reported interaction effects between irrigation and N on cane yield. nformation available is not very conclusive. Moreover, none of the scientists took into account the pre- and post-monsoon growing seasons of sugarcane in their investigation. The present stndy was designed to study the interaction effect of soil moisture and N levels on the yield and quality of sugarcane. MATERALS AND METHODS The field experiment was conducted at the Uttar Pradesh Agricultural University, Pantnagar, Nainital, North ndia, during 1968-69. The treatments consisted of all combinations of 4 soil moisture regimes and 5 N levels. Two sets of moisture treatments were selected, 1 for the pre-monsoon and another for the post-monsoon season. Pre-monsoon treatments Post-monsoon treatments Symbols rrigation applied when: 1. 25% of the available moisture 50% of the available 11 moisture 2. 50% of the available moisture 75y0 of the!available 12 moisture 3. 75y0 of the available moisture 100% of the available 13 moisture 4. 100yo of the available moisture No irrigation. 14 The post-monsoon irrigations were stopped 2 months before harvesting in order to ripen the cane. The following levels of N were applied: no N (No), 75 kg N/ha (N,), 150 kg N/ha (N,), 225 kg N/ha (N,) and 300 kg N/ha (N4). The experiment was laid down in a split plot arrangement, with 3 replications. Soil moisture regimes were taken as main plot and N levels as sub-plot treatments. The sugarcane variety Co 1158 was planted on 15th Feb, 1968, in furrows. Forty 3-bud seedpieces were planted in each 10-m length of row. Nitrogen was applied in the form of urea and ammonium sulphate as basal dressing and top-dressing, respectively. A basal dose of 80 kg each of P,O, and K,O/ha as single superphosphate and muriate of potash, respectively, was also applied at planting. Total rainfall received during the crop cycle was 1537 mm, of which 1467 mm were received from June to the 1st week of Oct. After providing 1 uniform irrigation, soil moisture content in the soil at a depth of 30 cm was recorded in each plot at periodic intervals by gravimetric

p. P. SNGS, GOVNDRA WNGK 855 method. When the specified moisture regime was reached, the soil moisture deficit UP to a depth of 0-60 cm was determined by taking soil samples in each plot, and the quantity of water required to bring the plot to field capacity was calculated with the help of the formula suggested by Richards (1954). The required amount of water was measured by a 15-cm size Parshall Flume. Soil moisture content at 0-60 cm depth was recorded before each irrigation and 3 days after each irrigation. These data were used to calculate the rate of water use, evapotranspiration ratio, consumptive use, water use efficiency and the seasonal water requirement. RESULTS AND DSCUSSON Cane Yield and Yield Contributory Characters Data on number of shoots/ha, plant height, millable canes/ha, number ofinternodeslcane, diameter of cane and cane yielcl are given in Table 1. Table 1. Effect of different soil moisture regimes and levels of N on the growth, ~ield and ~ield contributory characters of sugarcane. Shoots/ha Plant height Millable nter- Diameter Cane (cm at caneslha nodes/ of cane yield harvest) (000) cane (a) (ton/ha) C.D. (5%) 9.1 9.1 N.S. 7.9 N.S. N.S. 7.44 - C.D. (5%) N.S. N.S. 8.3 N.S. N.S. N.S. 11.43 The differences in number of shoots under irrigation treatments were found to be significant at both the stages.,,, and,, which were at par, produced significantly more shoots as compared to,. At harvest, irrigation treacments did not influence plant height, number of internodeslcane and diameter of the cane. The differences in millable canes qnd cane yield due to moisture treatments were found to be satistically significant, The significant positive influence of,,, and, on number of millable canes was observed over the, regime. The highest no. of millable canes were produced by the, regime, which was significantly higher over,. n case of cane yield,,,, and, remained at par but produced significantly higher yield over \,. f c Treatment, produced the highest caharyield of 102; ton/ha, which was

856 RRGATON 5.83, 5.31 and 17.97% higher than,,, and,, respectively. The variations in cane yield/ha due to soil moisture regimes followed the same trend as the number of millable canes/ha. Application of N only significantly increased the plant height and cane yield. Nitrogen treatments N,, N,, N, and N, produced significantly taller plants and higher yields over the check (no N), but they did not vary significantly among themselves. Moisture and N nteraction The interaction effects of moisture regimes and N levels on the cane yield were significant. Data are presented in Table 2. Table 2. nteraction effect of moisture regimes and levels of N on the cane yield (ton/ha). Nitrogen levels rrigation No N Nz N3 N4 Mean 11 69.29 99.57 100.57 106.87 105.96 96.45 12 93.82 94.76 102.35 97.64 96.07 96.39 13 96.73 99.95 107.72 100.92 105.08 102.08 4 85.55 92.54 83.84 85.84 84.95 86.53 Mean 86.35 96.71 98.62 97.82 97.99 C.D. (5%) for moisture regimes 7.44 C.D. (5%) for N levels 5.72 C.D. (5%) between 2 moisture regimes at constant and varying N levels 11.72 C.D. (5%) between 2 N levels at constant and varying moisture regimes 11.49 At N, and N, levels, the increase in yield due to,,, and, over, was found to be significant. At the N, level, only the, regime produced significantly higher cane yield over,. The highest cane yield of 108 ton/ha was observed at,-n, and the lowest of 69 ton/ha at,-no. Quality Studies The juice was analysed at harvest for brix, sucrose and reducing sugars. Purity coefficient, available sugar percent in cane and available sugar/ha were computed. The data on these characters are prbented in Table 3. The sucrose content of juice, available sugar percentage in cane and available sugarlha were affected significantly due to moisture treatments. The treatments, and, remaining at par gave significantly higher sucrose in juice over, and,. The available sugar percentage in cane was significantly higher under the, regime as compared to, and,. Treatments,,, and, produced significantly higher available sugarlha over,, and treatment, was found to be superior over all other moisture regimes. Nitrogen application significantly increased the reducing sugar in juice and available sugar/ha over the check. Highest available sugar was observed in the N, treatment. The significantly higher sucrose percentage in juice and available sugar percentage in cane under, and, regimes show the beneficial effect

p. P. SNGH, GOVNDRA SNGH 857 f Table 3. Effect of soil moisture regimes and N levels on available sugarlha and its contributory characters. Reducing Purity Available Available Sucrose sugar coeffi- sugar yo sugar Treatment Expression Brix % % cient in cane (tonlha) 11 63.4 17.4 15.0 0.24 86.1 10.2 9.76 z 63.0 17.6 15.4 0.22 87.0 10.6 10.25 13 64.7 17.9 15.7 0.20 87.6 10.8 10.99 4 62.5 17.3 14.9 0.19 86.2 10.3 8.86 C.D. (5%) N.4. N.S. N.S. N.S. N.S. 0.3 0.70 No 63.9 17.6 15.2 0.19 86.6 10.5 8.99 N 63.2 17.7 15.6 0.25 87.8 10.7 10.39 N2 62.9 17.2 15.2 0.20 86.9 10.4 10.32 N3 63.3 17.5 15.2 0.24 86.1 10.3 10.09 N4 63.3 17.4 15.1 0.26 86.3 10.4 10.05 C.D. (5% N.S. N.S. N.S. 0.06 N.S. N.S. 0.71 of pre-monsoon irrigations at longer intervals and an adverse effect of relatively frequent irrigations. Nitrogen application resulted in significant increases in cane yield. On the average, cane yield increased up to 150 kg N/ha, but the doses higher than this reduced the yield, though not significantly. The higher doses of nitrogen (above 150 kg N/ha) resulted in severe lodging of cane. Moisture Studies Data collected on different soil moisture studies are presented in Table 4. Table 4. Evapotranspiration, water use efficiency and seasonal water requirement under different moisture regimes. rrigation treatment tem 11 12 3 14 Evapotranspiration ratio (based on cane yield) 0.234 0.219 0.172 0.193 Water use efficiency (based on cane yield) 4.269 4.554 5.791 5.163 Seasonal water requirement (cm) 224.58 216.93 183.03 162.24 t appears from the data that the moisture treatments had the greatest effect on consumptive use of water. The average consumptive use (mm/day) increased with increasing moisture availability. The averagelday consumptive use of water was lesser during the post-monsoon period as compared to pre-monsoon period. The total water requirement also increased with the moisture availability. t is evident from the data that the evapotranspiration ratio was lower in the, regime compared to the, and, regimes. This was due mainly to higher

858 RRGATON yield and less amount of water applied in, regime. The, regime proved to be more efficient in the productive utilization of water. The total water requirement was highest in the case of the, regime. ACKNOWLEDGEMENTS The authors are thankful to Dr. R. L. Paliwal, the then Director of the Experiment Station, U.P.A.U., Pantnagar, for providing the necessary facilities for conducting the experiment. Sincere thanks are also due to Dr. K. C. Sharma, Agronomy Department, for timely help extended to us. ' REFERENCES Bhoj, R. L. 1962. rrigation and nitrogen requirements of sugarcane ratoons. ndian J. Sugarcane Res. & Dev., 6:131-137. Clieema, S. S., and M. C. Moolani. 1968. Effect of soil moisture regimes and nitrogen levels on growth and yield of sugarcane. Abstract presented at "Symposium in Agronomy of New Crop Varieties Under rrigated and Unirrigated Conditions" held at U.P. Agricultural University, College of Agriculture, Pantnagar (Nainital). Cheema, S. S*., and M. K. Moolani. 1970. Soil moisture in sugarcane (Saccharum oficinal-urn L.). ndian J. Agric. Sci., 3:273-282. Choudhury, J. C. 1961. Effect of irrigation and ammonium sulphate on the growth, yield and quality of sugarcane (Co 453). ndian Agri., 4:33-43. Dillewijn, C. V. 1952. Botany of Sugar Cane. The Chronica Botanica Co. Waltham, Mass. p. 136-161. Humbert, R. P. 1968. The Growing of Sugar Cane. Elsevier Pub. Co., New York. p. 311-390. Narasimha Rao, G. 1969. Studies on efficient utilization of irrigation water for sugarcane. A paper presented at "All ndia Symp. On Soil and Water Management" held at P.A.U.. Hissar. Narasimha Rao, C., and M. M. Satyanarayanan. 1960. Studies on [he influence of soil moisture in relation to nitrogenous fertilization on yield and quality of sugarcane. Proc. 4th Conf. Sug. Cane Res. Wrkrs, ndia. p. 97-105. Richards, L. A. 1954. Diagnosis and mprovement of Saline and Alkali Soils. U.S. Dept. Agric. Handbook 60. Singh, H., P. A. Adlakha, and M. M. S. Thakur. 1960. Some irrigational studies with important sugarcane varieties in the Punjab. ndian J. Sugarcane Res. & Dev., 4:103-110. Varma, H. P. 1965. Studies on the interrelation of levels of nitrogen and water duty in sngarcane varieties planted in spring. ndian Sugarcane J., 9:219-222.