Effects of differential irrigation practices on yield of sugarcane at Kenana Sugar Scheme, Sudan

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1 Effects of differential irrigation practices on yield of sugarcane at Kenana Sugar Scheme, Sudan Dafa alla M. Abdel Wahab 1 Abstract This study was conducted for two consecutive seasons (24/5-25/6) at Kenana Sugarcane Research Farm (13.1 ºN and 32.4 ºE), in a montmorillonitic clay soil, with 65 7% clay and ph value of 7.5 to 8.5. The objective of this study was to investigate the effects of different irrigation intervals at different s of sugarcane (cultivar Co 686) development on yield and yield components. Three development s were defined: (i) from planting to full canopy (Early-season ) during which two irrigation intervals (12 or 17 days) were applied; (ii) from full canopy to early maturity (Mid-season ) during which two irrigation regimes (7 or 12 days) were factorially imposed on i; (iii) during ripening three irrigation regimes (7, 12 or 17 days) were also factorially imposed on those of i and ii. This provided 12 treatments in the final s of cane growth designated as; T1, T2, T3, T4, T5, T6, T7, T8, T9, T1, T11 and T12, respectively. In both experiments, the differential irrigation treatments were applied 45 days after sowing. The reference evapotranspiration during different crop growth s was computed using Penman-Monteith approach. The amount of water required for irrigating sugarcane plants was calculated according to its phonological s. The results of the differential analysis of the effects of different irrigation intervals at each of the developmental s revealed that irrigation at 12 or 17 days intervals during the early and late season s produced significantly greater cane and sugar yields. Whereas, shorter irrigation intervals (7 days) during the mid-season stag, significantly increased cane, sugar yield and irrigation production efficiency (IPE). Introduction Sugarcane originated in Asia, probably in New Guinea. Most of the rainfed and irrigated commercial sugarcane (Saccarum officinarum) is grown between latitudes 35 N and S of the equator. Sugarcane crop requires a long, warm growing season with a high incidence of radiation and adequate moisture, followed by a dry, sunny and fairly cool weather during ripening and harvesting period (Cobley, 1976). Sugarcane has a long growing season and the normal length of the total growing period varies between 9 months to 24 months in Hawaii, but it is generally 15 to 16 months. Plant (first) crop is normally followed by 2 to 4 ratoon crops each taking about 1 year to mature. Growth of the stool is slow at first, gradually increasing until the maximum growth rate is reached after which growth slows down as the cane begins to ripen and mature. Though sugarcane can grow on heavy or light soils, they must be more than one meter deep, with ph in the range of 5 to 8.5, well-aerated and have a total available water content of 15 percent or more. Knowledge of water relations is fundamental to improved crop management in regions where irrigation is practiced In 1979 Doorenbos and Kassam stated that frequency and depth of irrigation should vary with growth periods of the cane. And they added that during the establishment of young seedlings, light, frequent irrigation applications are preferred. Whereas, 1 Kenana Sugar Research Station 1

2 during the stem elongation and early yield formation, irrigation interval can be extended but depth of water should be increased. All irrigation scheduling methods consist of an irrigation criterion that triggers irrigation and an irrigation strategy that determines how much water to apply. Irrigation scheduling methods differ by the irrigation criterion or by the method used to estimate or measure this criterion. A common and widely used irrigation criterion is soil moisture status. Borden and Denison (1942) stated that optimum water management can be established by considering the of development of the cane, the rate of consumptive use, depth of rooting, efficiency of irrigation, the percentage of available water used by the crop and water holding capacity of the soil. Depending on climate, of crop growth and available soil moisture content, water requirements of sugarcane range between 15 and 25 mm, evenly distributed over the growing season (Doorenbos and Kassam 1986). Cavazza and Gammino (1996) indicated that frequent irrigation of seven to ten days in New Guinea produced the highest cane and sugar yields, although there were differences in yield from season to season. Elfadil (1969), at Guneid Research Station (GRS), considered only the amount and intervals of irrigation without considering the moisture content of the soil. The results of a study carried out by Mirghani et. al. (1998) at GRS indicated that the shorter intervals of seven days produced significantly greater cane and sugar yields than longer intervals of 14 days, but the opposite was true regarding the percentage of fibre., Abdel Wahab (22), at Kenana Scheme found that the water required by sugarcane increases gradually with plant development, and the quantities of irrigation water required in the crop root zone amounted to17221 and 2572 m3 ha- 1 season-1 for ratoons and plant cane, respectively. Materials and Methods This study was conducted for two successive seasons (24/5-25/6) at Sugarcane Research Farm to investigate the effects of irrigation intervals at different s of sugarcane (cultivar Co 686) development on yield and yield components at Kenana Sugar Scheme, Sudan. Kenana Scheme is located on the eastern bank of the White Nile river, 3 km south of Khartoum at an altitude of 41 m above mean sea level (msl), a latitude of 13º1` N and a longitude of 32º 4`E. The climate is tropical dry, hot, semi-arid with daily mean maximum temperature of 39.4 ºC and the corresponding mean minimum temperature was 2.2 ºC. The mean annual rainfall was 278 mm (for the period 1977 to 26) and the mean relative humidity at 8: a. m. was about 49 %. The soil of the area is heavy montmorillonitic clay, brown in colour, quite uniform and alkaline in reaction (ph ranged between 7.5 and 8.5). It is non-saline non-sodic containing about 65% clay, 24% silt and 11% sand, with very low infiltration rate (3 cm 3 /m/hr). The irrigation treatments were designated with the objectives of studying the effects of different irrigation intervals at different s of sugarcane development on yield and yield components. Three development s were defined: (i) from planting to full canopy (Early-season ) during which two irrigation intervals (12 or 17 days) were applied; (ii) from full canopy to early maturity (Mid-season ) during which two irrigation regimes (7 or 12 days) were factorially imposed on i ; (iii) during ripening three irrigation regimes (7, 12 or 17 days) were also factorially imposed on those of i and ii. This provided 12 treatments in the final s of cane growth nominated as, T1, T2, T3, T4, T5, T6, T7, T8, T9, T1, T11 and T12, respectively (Table 2). In both seasons, the differential irrigation treatments were applied 45 days after sowing. The whole experiment was replicated three times. 2

3 The sugarcane cultivar (Co 686) was planted on the second of November. Each plot consisted of 4 rows, each were 5 m long and 1.55 m apart. Plots were separated by 5 m paths from all directions to minimize effects of lateral moisture movement. These treatments continued till the crop was 13 months old. During this period, the different treatments received different irrigation intervals as shown in Table 2. Then the irrigation was stopped and the cane was kept as dry-off for one month before harvesting. The reference evapotranspiration (ETo) for Kenana area was computed (Table 1) using the FAO- Penman-Monteith approach (Smith, 1991) and the CROPWAT software. CROPWAT computed the reference evapotranspiration in mm per day for each month of the growing season upon entry of the following meteorological data taken from Kenana Meteorological Station: Monthly mean minimum and maximum temperature. Relative humidity (%) at 8 : am. Wind speed (km/day). Sunshine hours (hour). Solar radiation (M J/m 2 / day). Daily rainfall was measured during the rainy season using a rainfall gauge. Soil samples for gravimetric moisture determination were taken at 2 cm increments to a depth of 1 cm using an auger. Sampling was made one day before irrigation and 3 days after irrigation throughout the growing season. The wet weight (Ww) was determined and the samples were oven dried at 15 ºC for 24 hours (Farbrother 1973). The dry weight (Dw) was determined and the soil moisture (Mc) was calculated as: Mc= Ww Dw. (1) The percentage of moisture content (% Mc) on dry weight basis was calculated as: Ww Dw % Mc = 1..(2) Dw Then, the gravimetric moisture content (w/w) was converted to volumetric values (v/v) through multiplication by dry soil bulk density (Farbrother 1973). The seasonal amount of water requirement (CWR) for sugarcane crop was determined as a function of the local climate, crop and soil data as: CWR = ETo Kc (3) The irrigation production efficiency (IPE) which is defined as the ratio of crop yield to seasonal irrigation water applied including rain (Howell 1994) was calculated using the following equation: IPE= Y. (4) SI Where IPE is the irrigation production efficiency (ton/ha/mm), Y is the yield (ton) and SI is the seasonal irrigation water applied including rain (mm). During this period, the different treatments received different irrigations as shown in Table 4. The cane was harvested at the age of 14 months and the following growth and yield parameters were determined. Stalk height and stalk diameter: At harvest time ten stalks were chosen randomly from the two inner rows of each plot. Stalk height was determined from the soil surface to the top most visible dewlap following the procedure described by Clements (198). Diameter of stalk was also measured using a vernier caliper at 3 cm above the soil surface 3

4 Cane yield: All millable stalks in the two inner rows of each plot were cut at ground level and arranged in bundles manually. Utilizing a tractor power, the harvested cane was weighed by a portable spring balance, then the final cane yield (ton ha-1) was calculated as: ton cane/ha = (weight of millable stalks in 1 m row (kg) x 4 rows x 1/1 x plot area (m 2 ) Where: 1 = area of hectare in m 2 1 = kilogram in one ton Sugar yield was obtained by the following equation: Ton sugar/ha = (ton cane / ha) x ERS.. (5) ERS = (weight of cane in cane in tons/ha x recovery) /1... (6) Where: ERS is the estimated recoverable sugar. Data was subjected to the analysis of variance procedure using SAS/STAT (199). Results and Discussion Climatic data for the two successive seasons (24/5 and 25/6), collected from the Sugarcane Research Meteorological Station, were used for the prediction of the reference evapotranspiration (ETo) during different crop growth s using Penman-Monteith approach. The results of Table 1 show that the mean annual values of the reference evapotranspiration are 5.4 and 5.3 mm/day for 24/5 and 25/6 seasons and the values for March and April (the highest months) are very close. During August (rainy season), the reference evapotranspiration reaches its minimum value of 3.9 mm/day. Before sugarcane crop reaches its full canopy, the crop coefficient (Kc) increases up to more than unity and then declines reaching a minimum value of.6 at maturity (Table 1). These sets of data were used to obtain the final estimates of sugarcane water requirements. Sugarcane water requirements. The water requirements of sugarcane crop (ratoons and plant cane) are given in Table 1. Generally, the results reveal that the crop water requirements of sugarcane increase gradually with plant development and then decline at the late growth (Figure 1). During February, March and April, the water required by the sugarcane crop reaches its maximum value. This is mainly due to the high atmospheric evaporative demand during summer and commencement of the peak use of cane growth. During the rainy season, the water required by sugarcane crop shows its minimum value. Similar results were reported by Farbrother (1973) in Gezira Research Station. Soil water profile Average values of the soil water content are presented in Table 3. The difference between water content before and after irrigation was used as one measure to investigate the effect of differential irrigation practices on sugarcane yield. The results indicate that, the volumetric soil moisture content was closely related to the differential irrigation treatments. The remaining soil moisture content at 12 days irrigation intervals during the early season for treatments T1 to T6 was similar. Whereas, for treatments T7 to T12 at 17 days irrigation intervals remained lower than for the other treatments before irrigations. It was also observed that soil moisture content increased after each irrigation depending on the treatment. The present findings also indicate that the remaining soil moisture in the treatment of 17 days irrigation interval in the in which irrigation was made was lower than that of the all other treatments. 4

5 Stalk height and diameter Table 5 shows the effects of irrigation intervals at different s of sugarcane development on stalk height and diameter. Generally, treatment T2 (which irrigated every 12, 7, 12 days during the early-season, mid-season and late-season, respectively) produced the tallest plants followed by T1 and T3 (which irrigated every 12, 7, 12 days during the early-season, mid-season and late-season, respectively). The results of the effects of differential irrigation practices on stalk diameter followed the same trend of stalk height. These results agreed with previous findings of Gorbet and Rhoads (1975) who concluded that maximum plant height and diameter are expected to be obtained if frequent and heavy irrigation water is applied throughout the mid-season of sugarcane crop which is the sensitive s. Cane and sugar yield Table 6 show the effect of differential irrigation practices on cane and sugar yield, water used and irrigation production efficiency (IPE). Generally, it was observed that the highest cane and sugar yield was obtained from treatments T2 (irrigated every 12, 7 and 12 days intervals at early-season, mid-season and late-season s, respectively. On the other hand the lowest yield correspond to treatments (T4, T5, T6, T1, T11 and T12) which was the reflex of the fact that mid-season of cane growth required frequent irrigations with increased depth of water application. Supporting evidence was reported by Abdel Wahab (26), who stated that the reduction in cane and sugar yield was mainly due to reduction in stalk height and diameter. Panje and Srinivasan (1956), stated that prolonging irrigation intervals during mid-season reduced the rate of vegetative growth Differential analysis of the effects of different irrigation intervals at each of the developmental s (Table 6) also revealed that cane and sugar yield were not significantly (P<.5) affected by longer irrigation interval (12 or 17 days) during the early and late-season. Whereas, shorter irrigation interval (7 days) during the mid-season significantly (P<.5) increased cane and sugar yield. Irrigation production efficiency (IPE) The relationship between total amount of water applied for each irrigation treatment and the corresponding cane and sugar yields obtained are shown in Table Results of the evaluation of irrigation production efficiency (IPE) indicated that irrigating every 12, 7 and 12 days intervals at early-season, mid-season and late-season s, respectively produced the highest IPE in both seasons (Table 7). This is mainly due to increased cane and sugar yields of the best schedule irrigation treatment (T2). However, increasing the irrigation interval to 12 days at mid-season (T6 and T12) led to decreased cane yields and irrigation production efficiency (IPE). The same trend was reported in Australia by Raine and Bakker (1996). Conclusion Following the results of this work, it is concluded that the longest irrigation interval (17 days) led to decreased cane yield and irrigation production efficiency, whereas the best cane yield and irrigation production efficiency was obtained from treatments T2 (irrigated every 12, 7 and 12 days intervals at early-season, mid-season and late-season s, respectively). 5

6 Recommendations Based on two season s results the author recommend that sugarcane should be irrigated every 12, 7 and 12 days intervals at early-season, mid-season and late-season s, respectively. Because it reduce volume of water applied by 16% and increased cane yields and irrigation production efficiency in both seasons. References Abdel Wahab, D. M.; Adeeb, A. M. and Adam, H. S. (22). Determination of sugarcane crop wter requirements at Kenana Sugar Scheme. University of Khartoum Journal of Agricultural Science1 (2), Abdel Wahab, D. M. (26). Evaluation of deficit irrigation scheduling based on sugarcane growth s. 41 st Crop Husbandry Committee Meeting, ARTC, Wad Medani, Sudan. 23 Dec, 26. Borden, R. J. and F.C. Denison. (1942). Study of optimum crop length. Hawaiian Planters` Rcord. 46: Cavazza, L. and Gammino, M. (1996). Evaluation of an irrigation scheduling: From Theory to Practice, Proceedings ICID/FAO Workshop, September 1996, Rome. Water Report No. 8, FAO, Rome. Cobley, L. S. (1976). An introduction to the Botany of Tropical Crops. 2nd Edtion. Longman, Lndon and New York. Pp 64. Clements, H. F. (198). Sugarcane Crop Logging and Crop Control: Principles and Practices. University Press of Hawaii. Honolulu, Hawaii, USA. Doorenbos J. and Kassam (1979). Guidelines for predicting crop water requirements. Irrigation and Drainage Paper No. 24, 156 p. FAO, Rome, Italy. Doorenbos, J. W. and A. H. Kassam. (1986). Yield response to water. Irrigation and Drainage. Paper No. 33. FAO, Rome, Italy. Elfadil, A. (1968). Annual report of Guneid Research Station, 1968/ Farbrother, H. G. (1973). Water requirements of crops in the Gezira. Annual Report of the Gezira Research Station, 1972 / 73, pp Gorbet, D. W. and Rhoads, F. M. (975). Response of two peanut cultivars to irrigation and kylar. gronomy Journal 67, Mirghani, F. S.; Mohamed, A. E.; Mohamed, H. A. and Mohamed, E.Y Determination of sugarcane crop water requirements at Elguneid Sugar Scheme. Sudan Journal of Agricultural Research 1 (1), Panje, R. R. and Srinivasan, K. (1956). studies in Saccharum spontaneum. A note on the Growth sequences of Saccharum spontaneum. Proc. 1 th Congr. ISSCT, Elsevier, pp Raine, S. R. and D. M. Bakker. (1996). Increasing the efficiency of furrow irrigation for sugarcane production in the Burdekin. Proceeding of the 12 th National Irrigation Association of Australia Conference, Tam worth, May, pp SAS Institute. (199). SAS/STAT user`s guide 199 ed. SAS Institute, Inc. Cary, NC, U.S.A. Smith, M., R. G. Allen, J. L. Monteith, A. Perrier, L. Pereira and A. Segeren. (1991). Report of the Expert Consultation on Procedures for Revision of FAO Guidelines for Prediction of Crop Water Requirements. UN-FAO, Rome, Italy, 54 p. 6

7 Table 1. Mean monthly reference evapotranspiration (ETo) and sugarcane crop water requirements (CWR) Development Stages Month ETo (mm/day) K c CWR (mm/ day) 24/5 Days of Month CWR (mm/ month) Rainfall (mm/ month) Early - season Mid - season - Late - season - Nov.24 Dec Jan-5 Feb. March April May June July Aug. Sept Oct. Nov Total / Early - season Mid - season - Late - season Nov. 25 Dec Jan-6 Feb. March April May June July Aug. Sept. Oct. Nov Total

8 CWR (mm) Nov Dec Jan Feb March April May June July Aug Sep Oct Months of the crop season Figure 1. Mean monthly sugarcane crop water requirements Table 2. Irrigation intervals applied during each development Irrigation intervals Growth Early season Mid-season Late - season T T T T T T T T T T T T Table 3. Mean values of the soil moisture for different growth s at different treatments. Early - season Mid-season Late - season Soil Soil Remaining Remaining Remaining moisture 3 moisture 3 soil soil soil days after days after moisture moisture moisture irrigation irrigation 8 Soil moisture 3 days after irrigation T T T T T T T T T T T T

9 Table 4: Number of irrigations applied during each development. Early-season 15 days 1/11-1/4 Number of irrigations Mid-season 18 ( 9 days irr) 1/5-1/1 (7.8.9) Late - season 6 days 1/11-3/12 Total 39 days T T T T T T T T T T T T Table 5. Effect of irrigation intervals at different s of sugarcane development on stalk height and diameter. Stalk height (cm) Mean Stalk diameter (cm) 24/5 25/6 24/5 25/6 Mean T ab 358 ab abc 3.2 ab 3.1 T a 364 a a 3.6 a 3.4 T ab 354 ab ab 3.2 ab 3.1 T 4 32 d 336 cdef bcd 2.5 d 2.5 T ab 347 bcd cd 2.5 d 2.5 T 6 32 d 32 g bcd 2.5 d 2.5 T cd 325 fg d 2.7 cd 2.5 T abc 351 abc abc 2.9 bcd 2.9 T bcd 344 bcde abc 3.1 bc 3. T 1 3 bcd 3 efg d 3. bc 2.6 T bcd 35 abc abcd 2.7 cd 2.7 T bcd 333 defg abcd 2.7 cd 2.7 Mean C.V.% SE + LSD

10 Table 6. Effect of differential irrigation practices on cane and sugar yield. cane yield (ton / ha) Mean Sugar yield (ton / ha) 24/5 25/6 23/4 24/5 Mean T ab 166 ab a 24.2 abcd 24.1 T a 169 a a 26.5 a 26. T ab 166 ab ab 25.1 ab 24.7 T 4 15 fg 155 cde d 22.1 d 21.3 T gh 153 de abcd 2.5 cd 21.3 T h 151 e cd 22.4 cd 21.7 T ef 156 de abc 24. abcd 24. T abc 164 abc ab 24.8 abc 24.4 T 9 16 bcd 163 ab abc 24.4 abcd 24.1 T ef 153 de bcd 22.7 bcd 22.3 T cd 16 abcd bcd 23. bcd 22.8 T de 159 bcde bcd 22.8 bcd 22.5 Mean C.V.% SE + LSD

11 Table 7. Cane and sugar yield, water used and irrigation production efficiency (IPE). No. of irrigations Water applied (m 3 /ha) Cane yield (ton/ha) Sugar yield (ton/ha) (kg cane/ m 3 ) IPE (kg sugar/ m 3 ) 24/5 T T T T T T T T T T T T Mean /6 T T T T T T T T T T T T Mean