Determination of Optimum Nitrogen and Phosphorus Rate for Sugarcane at Finchaa Sugarcane Plantation

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1 Proc. Ethiop. Sugar. Ind. Bienn. Conf., 1: (2009) RESEARCH PAPER Determination of Optimum Nitrogen and Phosphorus Rate for Sugarcane at Finchaa Sugarcane Plantation Ambachew Dametie and Ademe Adenew Ethiopian Sugar Development Agency, Research Directorate P.O. Box 15, Wonji, Ethiopia Abstract Towards determining economic optimum rates of N and P fertilizers for sugarcane at Finchaa sugarcane plantation field studies were conducted from on the major soil types (Luvisols and Vertisols). During the experiment separate plots were established for each plantcane and the three ratoo which were treated as commercial fields prior to the study year. Nitrogen and phosphorous (urea 46 % N and DAP 18 % N and 46 % P2O5) treatments were applied at rates of 0, 115, 184, 253, and 322 kg ha 1 N with 0, 115, 207, and 299 kg ha 1 P2O5 in factorial combination. The treatments were laid out in randomized complete block design with three replicatio. Millable stalk population, cane and sugar yields and juice quality parameters were determined. ANOVA was made by coidering the two soil types as location. Moreover, benefitcost analysis was made by fixing unit cost of production of sugar at 3680 Birr t 1 and cost of urea at 6000 Birr t 1. The results of the study indicated that application of N and P had significant effect on cane and sugar yields; however, except for sugar yield at 1 st ratoon and for number of millable cane on plantcane, there was no interaction between nitrogen and phosphorus application. The yield respoe of sugarcane to applied nitrogen was stronger on Luvisols than on Vertisols. A highly significant (P<0.01) sugar yield respoe was obtained due to the application of P but any significant additional yield was not obtained when the amount of P applied increased above 115kg P2O5 ha 1 in all crop and soil types. Therefore, the economic optimum fertilizer rates recommended for Luvisols are 150 kg ha 1 urea for plantcane, 1 st and 3 rd ratoo; and 300 kg ha 1 urea for 2 nd ratoo. While on Vertisols, for plantcane and 3 rd ratoon 150 kg ha 1 urea, 1 st and 2 nd ratoo 300 and 450 kg ha 1 urea, respectively. Moreover, for all soil types and crop status application of 115 kg ha 1 P2O5 is recommended. Introduction Continuous sugarcane production without balanced nutrient management depletes the soil nutrients and in the long run cause the loss of productivity of the soil. On the other hand, in most countries, addition of fertilizers mainly nitrogen ISSN print version,

2 Ambachew D. and Ademe A. 118 and phosphorous improves cane and sugar yield. In this regard, available reports indicate that nitrogen fertilization improves cane elongation, population and tonnage; whilst, phosphorus and potassium have effect on rate of tillering and sucrose accumulation, respectively (Dillewijin, 1952; Kakde, 1985; Blackburn, 1991; Husingi, 1993). Both excess and lower nutrient supply have deleterious effects on cane and sugar yields such that nitrogen deficiency reduces cane yield while its excess levels delay maturity and reduces sucrose accumulation (Kakde, 1985). Similarly, phosphorus deficiency on sugarcane may result in reduced cane tonnage, but excessive phosphorus increases cane tonnage with a simultaneous decrease in sugar concentration (Gascho and Kidder, 1979; Glaz and Ulloa, 1994; Glaz et al., 2000). Thus, fertilizer rates should be determined based on yield respoe and economic profitability. Based on limited fertilizer studies conducted in Finchaa sugarcane plantation, tentative recommendatio of urea at rates of 150, 300, 350, 400 kg ha 1 for the plantcane, 1 st, 2 nd, and 3 rd ratoo and above, respectively, in combination with 250 kg ha 1 diammonium phosphate (DAP) are being applied. However, with change in price of fertilizer and sugar demand, continuous evaluation of optimum fertilizer rates for sustainable production has a paramount importance in cane sugar production (Havlin et al., 1999). Therefore, the objective of this study was to determine the optimum nitrogen and phosphorus rates for the plantcane and ratoo grown on Luvisols and Vertisols of Finchaa sugarcane plantation. Materials and Methods Description of the Study Area Finchaa sugarcane plantation is located at 9 o 30'10 o 00' N and 37 o 15'37 o 30' E with an altitude of m.a.s.l. The major soil types of the plantation are Luvisolss (70 %) and Vertisolss (30 %). Both soil types have slightly acidic reaction, low total N, OlsenP, and organic carbon content; while the available K values were relatively high. Methodology The study was conducted during cropping seaso on Luvisols and Vertisols of Finchaa. Separate experimental plots were established for the first four cuttings; and prior to the study year each experimental plots were treated as commercial fields. Nitrogen and phosphorous (urea 46 % N and DAP 18 % N

3 Determination of optimum N and P rate 119 and 46 % P) treatments were applied at rates of 0, 115, 184, 253 and 322 kg ha 1 N, and at rates of 0, 115, 207, and 299 kg ha 1 P 2 O 5 in factorial combination. The treatments were arranged in randomized complete block design with three replicatio. DAP was applied at planting while the remaining nitrogen was applied as urea at the age of 2.5 months. On ratoo both DAP and Urea were simultaneously applied at one month after ratooning. Sugarcane leaves (+3) were sampled at the age of five months and were analyzed for N, P and K (Sahlemedehin and Taye, 2000). Plant population was counted at the age of 10 months after planting or ratooning and at harvest. At harvest, 20 millable stalk samples were randomly taken from the middle four rows of each plot for measurement of girth, length, weight and juice quality. Juice quality parameters (Brix and pol %) were determined following the procedures of ICUMSA (1994). Cane yield was calculated from total millable stalk population per hectare and average cane weight. Data Analysis The data were analyzed using MSTATC computer package (MSTATC, 1988). ANOVA was made coidering the two soil types as location. Benefitcost ratios were calculated by assuming that 85 % of the experimental yield would be realized in commercial production and by fixing unit cost of sugar production at 3680 Birr t 1 and cost of urea at 6000 Birr t 1. The optimum fertilizer rates were recommended based on the higher benefitcost ratio associated with the highest net return. Results and Discussion Effect of N and P on Foliar NPK, Yield and Yield Component Results of analysis of variance of the effect of N and P fertilizers application on yield and yield components of the first four crops of sugarcane are presented in Table 1. Among the yield parameters sugar yield and millable stalk length were highly significantly (p<0.01) affected by the application of P on all crop status (except millable cane length on 2 nd ratoon) and by N on 2 nd and 3 rd ratoo (Table 1). Similarly, cane and sugar yields and millable stalk population were affected by nitrogen except on the 1 st ratoon of millable stalk population and sugar yield (Table 1). Except on cane yield, millable stalk length, and sugar yield of plantcane and cane yield of 3 rd ratoon all yield and yield components were significantly affected by soil types; nevertheless, interaction of soil type with nitrogen and phosphorus were variable with respect to different parameters and cuttings

4 Ambachew D. and Ademe A. 120 (Table 1). As a result, the interaction of nitrogen with soil type showed significantly high (p<0.01) effect on millable stalk population of 1 st and 2 nd ratoo, cane and sugar yields of 1 st ratoon, millable stalk population of 2 nd ratoon and significant (p<0.05) effect on millable stalk length of 1 st ratoon and cane and sugar yields of 2 nd ratoon. Table 1. Analysis of variance for the effect of N and P fertilizers on yield and yield components of sugarcane Crop status Plantcane 1 st Ratoon 2 nd Ratoon 3 rd Ratoon Source of variation Millable stalk length (m) Girth (cm) Millable cane population ( 000 ha 1 ) Cane yield (t/ha) Estimated recoverable sugar (%) Sugar yield (t ha 1 ) Soil (L) Nitrogen (N) L x N Phosphorus (P) N x P C.V. (%) Soil (L) Nitrogen (N) L x N Phosphorus (P) L x P N x P C.V. (%) Soil (L) Nitrogen (N) L x N Phosphorus (P) C.V. (%) Soil (L) Ns Nitrogen(N) L x N Phosphorus L x P C.V. (%) Due to the main effect of N (P<0.01) on sugar yield of plantcane and 3 rd ratoon, there was a 16 and 26.6% yield improvement over the control, respectively, at application rate of 115kg N ha 1 (Table 2). On the other hand, coequent to the interaction effect of N with soil type a sugar yield improvement of 37.3% on Luvisols (115kg N ha 1 ) of the 3 rd ratoon, and 9.9% on Vertisols (184kg N ha 1 ) of the 1 st ratoon, and 37 % on Luvisols and 28.9% on Vertisols of the 2 nd ratoon were registered; the rates that gave the above sugar yield improvement similarly increased cane yield by 39.2, 27.9, 36.5, and 29.1 %, respectively (Table 2).These yield differences could be attributed to the significant increase in stalk

5 Determination of optimum N and P rate 121 population and cane length due to application of nitrogen. Besides, the percentage of yield increase by nitrogen application was higher in ratoon crop than that of plantcane. Similarly, several authors (e.g. Husingi, 1993; Sundara, 2000) reported that N requirement of sugarcane ratoo is significantly greater than that of plantcane mainly due to their less nitrogen utilization efficiency; however, it declines gradually as the number of ratoo increased (Prasad, 1976; Kakde, 1985; Husingi, 1993). Table 2. Effect of nitrogen fertilization on yield and yield components of sugarcane Crop status Nitrogen (kg ha 1 ) Cane yield (t ha 1 ) Sugar yield (t ha 1 ) Luvisols Vertisols Mean Luvisols Vertisols Mean Plantcane Sig. Mean CV(%) LSD LSD Mea followed by the same letter for the same parameter in the same crop status are significantly different at P< 0.05 level of probability according to DMRT; = significant at P< I st Ratoon cd 151.8f c 18.39c cd 187.1e a 20.21c bc 194.2de a 23.59b ab 194.8d a 23.00b a 192.3d a 22.61b 25.2 Sig. Mean CV(%) LSD Ns nd Ratoon b 113.2c ef 16.37f a 137.1b bc 19.14de a 138.3b a 19.38d a 146.1b ab 21.10c a 152.0b ab 21.12c Sig. Mean CV(%) LSD rd Ratoon c 141.7b a 165.5a a 167.5a a 172.1a a 175.2a Sig. Mean CV (%)

6 Ambachew D. and Ademe A. 122 Application of phosphorous showed a significant (P<0.05) and highly significant (P<0.01) effect on stalk length and sugar yield (Table 3). When compared with the untreated, plots treated with 115kg P 2 O 5 ha 1 increased sugar yields by 14.1, 5.2, 6.0, and 3.1 percent, respectively on plantcane, 1 st, 2 nd and 3 rd ratoo. Thus, the results justified that the rate 115 kg P 2 O 5 ha 1 statistically found to be the best for all crop status regardless of soil types. Table 3. Effect of phosphorus fertilization on yield and yield components of sugarcane Crop status P2O5 (kg ha 1 ) Millable stalk length (m) Millable stalk population ( 000 ha 1 ) Cane yield (t ha 1 ) Sugar yield (t ha 1 ) Plantcane Sig. CV(%) LSD I st Ratoon Sig. CV(%) LSD nd Ratoon Sig. CV(%) LSD rd Ratoon Sig. CV(%) LSD The overall concentration of nitrogen and phosphorous in +3 leaf (TVD) showed a decreasing trend as the number of cuttings increased; however, with increasing applied N and P rates, foliar nitrogen and phosphorus concentration increased in both plantcane and ratoon on both soil types (Table 4). The result was in agreement with findings of Jasen et al (1990) that uptake of nitrogen appears to be strongly affected by application of phosphorus fertilizer, especially in soil

7 Determination of optimum N and P rate 123 with low Olsen s P values. According to Kamprath (1987) soils low in available nitrogen and phosphorus, nutrient absorption by plants was stimulated by application of nitrogen fertilizer. Table 4. Effect of the applied nitrogen and phosphorus fertilizers and cuttings on foliar NPK concentratio Fertilizer types N P Foliar concentration Crop status Luvisols Vertisols N% P% K% N% P% K% Plantcane st Ratoon nd 2 nd Ratoon rd Ratoon Plantcane st Ratoon nd 2 nd Ratoon rd Ratoon Economic Optimum N and P Fertilizers Rates The values of the benefit cost analysis of nitrogen application that was carried out by taking into account the cost of urea at 6000 Birr ton 1 and unit cost of production of sugar at 3680 Birr ton 1 is presented in table (5). Since there was no significant intercation between N and the two soil types with regard to sugar yield of plantcane and 3 rd ratoon the economic analysis was made for pooled values. Thus, the best economic optimum rates of urea were 150 kg ha 1 for plantcane, 1 st ratoon and 3 rd ratoon and 300 kg ha 1 for 2 nd ratoon on Luvisols while on Vertisols 150 kg ha 1 on plantcane and 3 rd ratoon, 300 kg ha 1 on 1 st ratoon and 450 kg ha 1 on 2 nd ratoon (Table 5). Moreover, application of 150kgha 1 urea on plantcane and 3 rd ratoon was found to give highest benefit on all soil types; nevertheless, where interaction of N with soil type was identified the best economic return was recorded at urea rate of 150kgha 1 on Luvisols, 300kgha 1 on Vertisols of 1 st ratoon, and 300kgha 1 on Luvisols and 450 kgha 1 on Vertisols of the 2 nd ratoon (Table 5).

8 Ambachew D. and Ademe A. 124 Table 5. Benefit cost ratio (BCR) and net return for selected urea rates. Crop status Plantcane 1 st Ratoon 2 nd Ratoon 3 rd Ratoon Soil type Description Urea rate (kg ha 1 ) Luvisols and Net return Vertisols B:C.R Luvisols Net return B:C.R Vertisols Net return B:C.R Luvisols Net return B:C.R Vertisols Net return B:C.R Luvisols and Net return Vertisols B:C.R Conclusion and Recommendatio Application of nitrogen and phosphorus had significant effect on cane and sugar yields, however, there was no interaction between nitrogen and phosphorus application. The respoe of yield and yield components of sugarcane grown on Luvisols and Vertisols to the applied nitrogen fertilizer rates was not the same since higher yield respoe was registered on Luvisols than on Vertisols. Moreover, application of phosphorous had yield respoe but any significant additional yield was not obtained when the amount of phosphorous applied increased on all cuttings and soil types. Therefore, the following economic optimum fertilizer rates are recommended:150 kg ha 1 urea for plantcane, 1 st ratoon and 3 rd ratoon; and 300 kg ha 1 urea for 2 nd ratoon on Luvisols; while on Vertisols 150 kg ha 1 urea for plantcane and 3 rd ratoon, 300 kg ha 1 for 1 st ratoon and 450 kg ha 1 for 2 nd ratoon. Moreover, for all soil types and cuttings application of 115 kg ha 1 phosphorous is recommended. References Blackburn F Sugarcane. Tropical Agriculture Series. Longman Singapore Publishers Private Ltd Dillewijin Van C Botany of sugarcane Woltham, Mass., USA. The Chronica Botanica Co. Book Dept. Gascho GJ and G Kidder Respoes to phosphorus and potassium and fertilizer recommendatio for sugarcane on South Florida. Florida Agricultural Experiment Station Bulletine No. 809 (technical). Univ. of Florida, Gainesville, FL.

9 Determination of optimum N and P rate 125 Glaz B, G Powell, R Perdomo and MF Ulloa Sugarcane respoe to phosphorus fertilizer in relation to soil test recommendatio on Everglades Histosols. Agronomy Journal. 92: Glaz B and MF Ulloa Sugarcane in monoculture or in rotation with sweet corn. Field Crops Research, 36: Havlin JL, JD Beaton, LT Samuel and LN Werner Soil fertility and fertilizers : An introduction to nutrient management. 6 th edition. Prentice HallUpper Saddle River, New Jersey. Husingi G Production of sugarcane: Theory and Practice. Spring Verlag. Bangalore, India pp ICUMSA ICUMSA Method Book. c/o British Sugar Technical Centre. Colney, Norwich NR7UB, England. Jasen GBH, FCT Van Der Eijk, D Smaling, JEMA Wolf, H Reuler A System for quantitative evaluation of the fertility of tropical soils. Geoderma, 46: Kakde JR Sugarcane production. Metropolitan Book Co. PLTD. New Delhi pp. Kamprath EJ Enhancing phosphorus status of maize resulting from nitrogen fertilization of high phosphorus soils. Soil Science Society of American Journal, 51: MSTATC MSTAT Version2.10. Crop and soil science department, Michigan State University. Sahlemedhin Sertsu and Taye Bekele Procedures for Soil and Plant Analysis.Technical Paper No. 74. National Soil Research Center. EARO. Addis Ababa. Sundara B Sugarcane cultivation. Vikas Publishing House Private Ltd., India.