Miguel Torres Bernal Instituto para el Mejoramiento de la Producci6n de Azhcar, Mexico DF, Mexico. Soil Units N kglha PzO:, kg/ ha

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1 Agronomy ADVANCES N SUGARCANE FERTLZATON N MEXCO Miguel Torres Bernal nstituto para el Mejoramiento de la Producci6n de Azhcar, Mexico DF, Mexico ABSTRACT n this study are analyzed the results of 40 experiments conducted in plant cane crops from 1972 to 1974 in Jalisco, Balsas, Tehuacan, Papaloapan-lstmo, Veracruz Central, Tabasco and Las Huastecas cane regions, including the central areas and sites along the Pacific and Gulf Coasts of Mexico. The field prod~lctivity and increment of sucrose in sugarcane have shown a differential response to NPK fertilization due to soil characteristics, and the results presented here lead to the following conclusions: 1. For the greatest productivity profit in the plant sugarcane crop, the recommended doses for soil units studied should be: \ Soil Units N kglha PzO:, kg/ ha Vertisols 120 to Luvisols 120 to to 120 Fluvisols 160 to Sucrose increment is affected negatively by nitrogen applications in areas of Vertisols and Fluvisols, but it increases in Luvisols. Phosphate promotes sugarcane maturity but potash did not increase the sucrose content in the three soil units in which experiments have been conducted. NTRODUCTFON The sugarcane growing areas of the Mexican 'ndustry are scattered along the Pacific and Gulf of Mexico coasts and on a transverse belt over the 19O parallel North latitude. There are, according to Arceneaux', 14 regions with specific productivity problems, so that it is necessary to do fertilizer trials in the different soils of each region. The present study involves 40 experiments conducted in plant cane crops from 1972 to 1974, in the sugarcane regions of Jalisco, Balsas, Tehuaczin, Papaloapan-stmo, Veracruz Central, Tabasco and Las Huastecas, the climatic characteristics of which, according to the Thornthwaite2 classification, modified by Contreras3, are shown in Table.

2 TABLE. Climatological characteristics of several cane regions of MBxico. P N lgarcane Temperature OC Annual rainfall iegion Med. Min. Max. mm Climate classification Jalisco Balsas Semi-dry with a rainfall deficiency of about cm in the winter and about 8 cm more in the autumn: semi-warm with uniform temperature regime Slightly humid and semi-dry, with a rainfall deficiency of 60 to 120 cm in the winter and 10 to 20 cm more in the summer; warm to temperate-warm with uniform temperature regime. Tehuacin Dry with deficient rainfall all the year round, with a total deficiency of about 80 cm; semi-warm with uniform temperature regime. Veracruz Central Very humid and super-humid, with almost no deficiency of rainfall in spring and an excess of 70 cm during the summer and autumn. / Warm with uniform temperature regime. Papaloapan-stmo Semi-humid to semi-dry with a rainfall deficiency in spring of 40 to 45 cm; warm with uniform temperature regime. Tabasco Humid to very humid, with a rainfall deficiency of about 40 cm in the spring and a large excess in summer and autumn of about 80 cm; warm with uniform temperature regime. Las Huastecas Semi-dry to moderately humid, with a rainfall deficiency up to 80 cm in spring and excess of 6 to 40 cm in summer and autumn; warm with uniform temperature regime.

3 M.T. BERNAL 1143 n these sugarcane regions, the physiographic, climatological, and topographical variations build up soils with different physical and chemical characteristics that, accordingly to the FAO/UNESC04 classification, modified by Floress for the country conditions, correspond to the following main units: a) Vertisols. These are described in the sugarcane regions of Jalisco, Balsas, Tehuacan and Las Huastecas. The relief is nearly level or slightly rolling with incipient gilgai micro-relief; the clay and clay-loam textures may cause cracking during the dry season. From the point of view of soil fertility 90% of the soils studied are deficient in nitrogen and 30% in phosphorus, while in potassium content they are markedly rich. They are light gray, dark grayish brown, dark brown and a very dark gray in color. The ph varies from slightly to medium alkaline. b) Luvisols. These are identified in the sugarcane regions of Jalisco, Veracruz Central, Papaloapan-stmo and Tabasco. These soils are undulating to nearly level (Veracruz Central and Papaloapan-stmo). Predominant textures in the A horizon are clay loams and clay-silty loams, brown to light brown in color. n the B horizon the textures are clayey and yellowish brown to reddish brown in color. The ph of the soils varies from slight to medium acidity. The natural fertility shows a lack of nitrogen in 81% of the soils. Phosphorus is deficient in 63% of the areas and potassium is a limiting factor in 69% of the sugarcane soils. c) Fluviosols. These are located in the sugarcane areas of Papaloapan- stmo and Tabasco. These are nearly level sugarcane soils. They are light brown to light gray in color. Common textures are loams and silty loams; the ph is slightly alkaline. The natural fertility shows a nitrogen deficiency in 100% of the sites while, 33% lack phosphorus. They are very rich in potassium. MATERALS AND METHODS The combinations of N, PzOs and K20 in the field trials were established by factorial design in random blocks with 4 replications. The work done in each experimental site was the following: 1. Soil sampling. Represenfative samples were taken from 0-30 and cm depth, and processed in the laboratory to define their physical and chemical properties which might be useful for their classification into different soil units. The analytical methods used were the following.

4 1144 AGRONOMY a) ph. Glass electrode (Potentiometer. Relation soil-water 1 :2). b) Texture. Bouyoucos (hydrometer). c) Color. Munsell Color Chart (comparison of dry soil). d) Organic matter. Walkley and Black (wct combustion). e) Total nitrogen. Kjeldahl. f) Available phosphorus. n acid soils, Truog; in alkaline soils, Olsen. g) Available potassium. Extraction with Morgan's universal solution, determination by flame photometer. The climatological characteristics and the results of the laboratory analysis make it possible to group the 40 experiments in this way: 21 in Vertisol areas, 16 in Luvisols, and 3 in Fluvisols. 2. Stalk sampling.?n each experimental site, and for each treatment, monthly samples'were obtained from 8 representative stalks for determinations by the Pol-ratio method of the Brix, sucrose % cane, purity, fibre, reducing sugars and moisture % in the 8-10 section of the cane stalks. For Vertisols, the sampling period was from 12 to 17 months, in Luvisols from 12 to 16 months; and in Fluvisols from 9 to 13 months. n each case, the last sampling occurred at the time of harvest. From monthly data ol cane sucrose, maturity curves were calculated, for eahh soil unit, by means of the equation: sucrose % = a + bx + cx2, where X represent the age of sugarcane. C RESULTS AND DSCUSSON The results and discussion are given below for each soil unit. 1. Effect of NPK fertilization on the yields of sugarcane and sugar in metric tons per hectare: 1. Vertisols. i 1 a) Nitrogen. There was a sugarcane response in 81 % of the nitrogen applications, in doses ranging from 120 to 240 kg of i N/ha, and this nutrient increased yields from 12 to 73 tons of cane and from 1.5 to 9.6 ton of sucrose per hectare. 4 b) Phosphorus. Only 10% of the areas gave a response to applications of this nutrient, with doses from 75 to 100 kg Pz05/ha, from which were obtained yield increments of! 13 to 16 tons of cane and from 1.6 to 2.0 tons of sucrose / per hectare. c) Pot_assium. The potassium level in these soils was high and addition of this nutrient did not have any effect on sugarcane or sugar yields. c \

5 ! 3. Fluvisols. a) Nitrogen. Under these soil conditions there was a sugarcane response in 63% of the N applications, from 120 to 220 kg of N/ha. Yields were increased from 22 to 72 tons of cane and from 2.2 to 8.0 tons of sucrose per hectare. b) Phosphorus. Response was observed in 56% of the P205 applications, from 60 to 12') kg P%O5/ha, that increased sugarcane yields From 6 to 28 tons of cane and from 1.2 to 3.9 tons ol sucrose per hectare. c) Potassium. n these soils, with a low potassium level, a high yield response was expected, but sugarcane gave positive results in only 25% of the experiments using 60 kg/ha of Kz. The increased yield obtained varied from 9 to 15 tons of cane and from 1.8 to 3.2 tons of sucrose per hectare. a) Nitrogen. A response was found in 67% of the applications with doses from 160 to 180 kg Njha. The yield increments were from 28 to 31 tons of cane and from 4.2 to 4.5 tons of sucrose per hectare. b) Phosphorus. Only in 33% of the experiments was a response to 90 kg Pz05/ha observed. This dose produced increments of 8 tons of cane and 2.4 tons of sucrose per hectare. c) Potassium. The soils under consideration are well provided with potassium, therefore sugarcane did not show a response to this nutrient Effect of fertilization with NPK on maturity curves of sugarcane. Vertisols. a) Nitrogen. Fig. 1 shows the effect of nitrogen levels on the sucrose accumulation in sugarcane. t is observed that with 120 kg N/ha the sucrose values at 10 to 12 months are lower than the check, but from 13 to 17 months the sucrose contents are similar to those of the check. On the other hand, with 240 kg of N/ha the values from 10 to 13 months are higher than the check, while from 14 to 17 months the sucrose content is lower. This shows that high nitrogen applicati'diis,,affect the sucrose accumulation in sugarcane. 5,i \ " / ;' 4 <

6 FGURE 1. The plant cane crop sugar yield as affected by N. Kg. N/ha AGRONOMY, b) Phosphorus. n Fig. 2 the effect of the phosphorus levels on sucrose accumulation in sugarcane is demonstrated. FGURE 2. The plant cane crop sugar yield as affected by P205. ~g Pz05/ha b ' ,

7 M.T. BERNAL c) Potassium. Fig. 3 shows the effect of potassium on sucrose accumulation in sugarcane. FGURE 3. Effects of K20 on sugar yield in vertisol soils. 2. Luvisols. t appears that, from 10 to 11 months, potassium promotes sucrose accumulation but, from 14 to 17 months, this nutrient tends to decrease the amount of sucrose by comparison with that of untreated plots. n general terms it can be said that plant cane growing in Vertisol areas reaches its point of maturity from 14 to 17 months, and should be harvested at that period to obtain the highest sugar recovery. a) Nitrogen. Fig. 4 shows the effect of this nutrient 011 crose accumulation. the su- At the rate of 120 to 240 kg of N/ha, sucrose contents are lower than in untreated plots from 12 to 15 months, but they are higher in samples taken at 16 months. We conclude that nitrogen applicatipns are favourable when climatological conditions are propitious For the plant to complete its growing period.

8 1148 AGRONOMY FGURE 4. Effects of Nitrogen on sugar-yield in luvisol soils. Kg. N/ha 11 l b) Phosphorus. Fig. 5 shows the effect of phosphorus on sucrose accumulatio~i in sugarcane. FGURE 5. Effects of P~OS on sugar yield in luvisol soils

9 . " M.T. BERNAL Behaviour in response to applications of phosphorus fluctuates in these soils. With applications of 60 kg of P~Odha, the sucrose values are at first higher than those of the check. They decrease from 13 to 14 months, but increase again to overtake those of the check from 15 to 16 months. With applications of 120 kg of PzOs/ha, the sucrose overtakes that of the check at 12 months. t decreases from 13 to 15 months but again increases at 16 months. c) Potassium. n Fig. 6 the effect of potassium on sucrose accumulation in sugarcane is demonstrated. FGURE 6. Effects of K,O on sugar yield in luvisol soils. Although a higher sucrose value was obtained at 12 months, the potassium effect from 13 to 16 months is detrimental to sucrose accumulation. Untreated plots, by contrast, indicate a higher degree of maturity. Under these soil condition~,~tb,q- plant crop must be harvested from 15 to 18 months, to lleach satisfactory maturity. 5, t. u, 2 $ Y",

10 1150 AGRONOMY 3. Fluvisols. a) Nitrogen. Fig. 7 shows the effect of nitrogen on sucrose accumulation in sugarcane. FGURE 7. Effects of Nitrogen on sugar yield in fluvisol soils. Age of plant n months Here it is observed that, during 9 to 10 months, the sucrose values where nitrogen has been applied surpass those of the check, but from 11 months to the harvest term, the sucrose content is higher in the plots without nitrogen, which indicates that this nutrient has a detrimental effect on sucrose accumulation. b) Phosphorus. Fig. 8 indicates the effect of phosphorus on sucrose accumulation in sugarcane. t is obvious that, from 9 to 13 months sucrose in the phosphorus plots generally surpasses that in plots without this nutrient. The recommended dose is 120 kg PrOs/ha.

11 ' 9 io 11 ii 13, c) Potassium. Figure 9 shows the effect of potassium on sucrose accumulation in sugarcane. FGURE 9. Effects of KzO on sugal- yield in fluvisol soils =,r/,, h' 1,i' '\

12 1152 AGRONOMY n general, 60 kg KnO/ha had a slight negative effect on sucrose accumulation, but the differences between plots with and without potassium are small until the harvest time. The cane grown in Fluvisol areas must be harvested from 11 to 13 months to obtain the highest sucrose recovery in the factory. CONCLUSONS The yields of sugarcane and the sucrose accumulation showed a differential response to NPK fertilization according to the characteristics of the soils, and the results presented here lead to the following conclusions: The plant cane crop needs only nitrogen applications in Vertisol and Fluvisol soils to attain higher productivity, whereas Luvisol areas need nitrogen and phosphorus nutrients. From the results of experiments we recommend the following levels of nutrients. N kg/ha P20.j kglha Vertisols 120 to Luvisols 120 to to 120 Fluvisols 160 to On sucrose accumulation in sugarcane, the results are: a) Nitrogen. This nutrient negatively affects sucrose accumulation in the Vertisol and Fluvisol areas but it promotes cane maturity in Luvisol soils. b) Phosphorus. The maturity of cane is favored with phosphorus applications mainly in the Luvisol and Fluvisol areas. c) Potassium. n the three soil units, studied the potassium did not increase the sucrose accumulation in sugarcane. REFERENCES. Arceneaux, G. (1953). La ndustria Azucarera de MCxico. Banco de MBxico, S.A. Tomo 1 (.& parte): Thornthwaite, C.W. (1948). An approach toward a rational classification of c!;- 1 mates. The Geographical Review. Vol. 38 (1): Contreras A., A. (1942). Mapa de las provincias climatol6gicas de la Repliblica Mexicana. nstituto Geogrbfico. Secretaria de Agricultura y Fomento. MBxico. 4. FAO/UNESCO. (1968). Definitions of Soil Units for the Soil Map of the World. (1 World Soil Resources Report 33. Roma. <

13 M.T. BERNAL 5. Flores M., G. et a/. (1972). Descripci6n y mapa de las unidades de suelos de la Rep6blica Mexicana, seg6n el Sistema de Clasificaci6n FAO/UNESCO (3er. ntento). Direccidn General de Agrologia. S.R.H. Mtxico. 6. Ortiz-Villanueva, B. er a/. (1960). Anhlisis de suelos y recomendacione's' de fertilizantes para la cafia de azhcar. MPA. Boletin TCcnico n.o 4:ll-37. AVANCES SOBRE ABONAMENTO DE CANA EN MEJCO M.T. Bernal RESUMEN En este trabajo se analizan los resultados de 40 experimentos desarrollados en ciclo plantilla de 1972 a 1974 en las regiones catieras de Jalisco, Balsas, Tehuacan, Papaloapan-lstmo, Veracruz Central, Tabasco y Las Huastecas, que se encuentran ubicadas en la parte central y a lo largo de las costas del Pacifico y del Golfo de Mexico. La productividad de campo y la acumulacidn de sacarosa de la catia de azllcar, manifest6 una respuesta diferencial a la fertilizacion NPK de acuerdo a las caracteristicas de 10s suelos, derivandose las conclusiones siguientes: 1. La caaa en ciclo plantilla para lograr su mas alta productividad requiere de la fertilizacion como sigue: Vertisoles 120 a Luvisoles 120 a a 120 Fluvisoles 160 a La acumulacion de sacarosa se afecta negativamente con las dosificaciones de nitrogono sobre todo en las Unidades de Sue- 10s Vertisoles y Fluvisoles, per0 se incrementa con este nutrimento en 10s suelos Luvisoles. El fosforo acelera la madurez de la catia y en cambio el potasio en las tres Unidades de Suelos estudiadas no incrementa el contenido de sacarosa de la catia de azlicar.