Irrigation

SOIL MOISTURE REGIMES AND LEVELS OF NITROGEN: EFFECTS ON T H E YIELD AND QUALITY

OF SUGARCANE

P. P. Singh and Govindra Singh U.P. Agricultural University

Pantnagar, Nainital, U.P., India

I 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. Agricul- tural University, Pantnagar (Nainital) during 1968-69. Irrigations 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. Irrigation 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.

INTRODUCTION

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 nec-

I essary to work out the optimum level of N and suitable moisture level. Irrigation experiments conducted so far in India 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 til- lering 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 mill- able cane over the driest regime of 90% depletion. They have also reported that tillering increased i f t h increasing soil moisture availability. Narasimha R ~ O (1969) reported that irrigation at 25y0 available moisture gave the highest cane

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yield, followed very closely by 50y0. Yield was significantly lowered at 75Vo avail- able moisture loss. He did not observe any reduction in juice quality by irrigat- ing cane more frequently. However, the best soil moisture regime reported by Cheema and Moolani (1970) in relation to cane yield was 50% depletion of avail- able soil moisture.

Very few scientists have reported interaction effects between irrigation and N on cane yield. Information available is not very conclusive. Moreover, none of the scientists took into account the pre- and post-monsoon growing sea- sons 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.

MATERIALS AND METHODS

The field experiment was conducted at the Uttar Pradesh Agricultural University, Pantnagar, Nainital, North India, 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

Irrigation applied when:

1. 25% of the available moisture 50% of the available 11 was depleted. moisture was depleted.

2. 50% of the available moisture 75y0 of the !available 1 2

was depleted. moisture was depleted. 3. 75y0 of the available moisture 100% of the available 1 3

was depleted. moisture was depleted. 4. 100yo of the available moisture No irrigation. 1 4

was depleted.

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 replica- tions. 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. Nitro- gen 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. SINGS, GOVINDRA 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 sea- sonal water requirement.

RESULTS AND DISCUSSION

Cane Yield and Yield Contributory Characters

Data on number of shoots/ha, plant height, millable canes/ha, number of- internodeslcane, 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, ~ i e l d and ~ i e l d contributory characters of sugarcane.

Shoots/ha Plant height Millable Inter- 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

I

The differences in number of shoots under irrigation treatments were found to be significant at both the stages. I,, I, and I,, which were at par, pro- duced significantly more shoots as compared to I,. At harvest, irrigation treac- ments 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 influ- ence of I,, I, and I, on number of millable canes was observed over the I, regime. The highest no. of millable canes were produced by the I, regime, which was significantly higher over I,. I n case of cane yield, I,, I, and I, remained at par but produced significantly higher yield over I\,. f c

Treatment I, produced the highest caharyield of 102; ton/ha, which was

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5.83, 5.31 and 17.97% higher than I,, I, and I,, 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 Interact ion

The interaction effects of moisture regimes and N levels on the cane yield were significant. Data are presented in Table 2.

Table 2. Interaction effect of moisture regimes and levels of N on the cane yield (ton/ha) .

Nitrogen levels Irriga-

tion No NI 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 I4 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 a t constant and varying N levels 11.72

I C.D. (5%) between 2 N levels a t constant and varying moisture regimes 11.49

At N, and N, levels, the increase in yield due to I,, I, and I, over I, was found to be significant. At the N, level, only the I, regime produced significantly higher cane yield over I,. The highest cane yield of 108 ton/ha was observed at I,-N, and the lowest of 69 ton/ha at I,-No.

Quali ty 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. T h e data on these characters are prbented in Table 3.

The sucrose content of juice, available sugar percentage in cane and avail- able sugarlha were affected significantly due to moisture treatments. The treat- ments I, and I, remaining at par gave significantly higher sucrose in juice over I, and I,. The available sugar percentage in cane was significantly higher under the I, regime as compared to I, and I,. Treatments I,, I, and I, produced signifi- cantly higher available sugarlha over I,, and treatment I, was found to be supe- rior 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 avail- able sugar percentage in cane under I, and I, regimes show the beneficial effect

p. P. SINGH, GOVINDRA SINGH 857

Table 3. Effect of soil moisture regimes and N levels on available sugarlha and its contributory characters.

f

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 Iz 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 I 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 NI 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. T h e 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 differ- ent moisture regimes.

Irrigation treatment

Item 11 12 I3 14

Evapotranspiration ratio (based on cane yield) 0.234 0.219 0.172 0.193 Water use efficiency (based on cane yield) I 4.269 4.554 5.791 5.163 Seasonal water requirement (cm) 224.58 216.93 183.03 162.24

I t appears from the data that the moisture treatments had the greatest effect on consumptive use of water. T h e average consumptive use (mm/day) increased with increasing moisture availability. T h e 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.

I t is evident from the data that the evapotranspiration ratio was lower in the I, regime compared to the I, and I, regimes. This was due mainly to higher

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yield and less amount of water applied in I, regime. The I, regime proved to be more efficient in the productive utilization of water. The total water requirement was highest in the case of the I, 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. Irrigation and nitrogen requirements of sugarcane ratoons. Indian J. Sugar- cane Res. & Dev., 6:131-137.

Clieema, S. S., and M. IC. 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 Irrigated 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.) . Indian J. Agric. Sci., 3:273-282.

Choudhury, J. IC. 1961. Effect of irrigation and ammonium sulphate on the growth, yield and quality of sugarcane (Co 453) . Indian 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 India 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, India. p. 97-105.

Richards, L. A. 1954. Diagnosis and Improvement 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. Indian J. Sugarcane Res. & Dev., 4:103-110.

Varma, H. P. 1965. Studies on the interrelation of levels of nitrogen and water duty in sngar- cane varieties planted in spring. Indian Sugarcane J., 9:219-222.