Fitociencia

 

Response of a fourth ratoon sugarcane crop to nitrogen, silicon, and lime fertilization

 

Respuesta del cuarto cultivo de soca de caña de azúcar a la fertilización de nitrógeno, silicio y cal

 

Gilmara Pereira da Silva*, Renato de Mello-Prado, Thiago Batista Firmato-Almeida, N. Regina de Campos-Nóia

 

Department of Soils and Fertilizers, Universidade Estadual Paulista Júlio de Mesquita Filho, Prof. route of access Paulo Donato Castellane, s/n, Jaboticabal, SP, CEP: 14884-900, Brazil. *Autor responsable. (gilmarapereira@agronoma.eng.br), (rmprado@fcav.unesp.br), (thibalmeida@gmail.com), (natalia_campos_17@hotmail.com).

 

Received: October, 2014.
Approved: May, 2015.

 

Abstract

Maximum efficiency of nitrogen (N) is attained when fertilizer is accompanied by silicon (Si). Therefore, the objective of this study was to evaluate the chemical attributes of the soil, the nutritional status, the yield of stalks, and the accumulation of N and Si by a fourth ratoon sugarcane (Saccharum sp.) crop, and the influence of N doses in the presence and absence of Si and lime. The study was carried out at the experimental farm of the UNESP Jaboticabal campus, state of São Paulo, Brazil. The experimental design was in a completely randomized block with a 5x2 factorial scheme: five doses of N (0, 40, 80, 120, and 160 kg ha^-1), and two corrective materials, silicate and lime; with four replications per treatment. The soil was characterized as distrophic Red Latosol, and the sugarcane variety was RB855156. During the experiment, the N (N-NH₄⁺ and N-NO₃^-) and Si content in the soil, the N and Si content in the leaf, production of stalks, and the accumulation of N and Si in the leaves and stalks were measured. Nitrogen fertilization associated with silicate and limestone increased the levels of N-NO₃^- and Si in the soil, and improved nutritional status and accumulation of N and Si in leaves and stalks of sugarcane; but, stalk production was lower when using silicate as compared to lime.

Keywords: Saccharum spp., nitrogen fertilization, silicate, limestone, stalk production.

 

Resumen

La eficiencia máxima de nitrógeno (N) se alcanza cuando el fertilizante de N se usa con silicio (Si). Por tanto, el objetivo de este estudio fue evaluar los atributos químicos del suelo, el estado nutricional, la producción de tallos y la acumulación de N y Si en el cuarto cultivo de soca de caña (Saccharum sp.), y la influencia de la dosis de N en presencia y ausencia de Si y cal. El estudio se realizó en la granja experimental del campus UNESP-Jaboticabal, estado de São Paulo, Brasil. El diseño experimental fue de bloques completos al azar con un arreglo factorial de 5x2: cinco dosis de N (0, 40, 80, 120 y 160 kg ha^-1), y dos materiales correctivos, silicato y cal; con cuatro repeticiones por tratamiento. El suelo se clasificó como Latosol Rojo distrófico y la variedad de caña de azúcar fue RB855156. Durante el experimento se midieron el contenido de N (N-NH₄⁺ y N-NO₃^-) y Si en el suelo, el contenido de N y Si en la hoja, la producción de tallos y la acumulación de N y Si en las hojas y tallos. La fertilización con N asociada con silicato y caliza aumentó los niveles de N-NO₃^- y Si en el suelo, lo cual mejoró el estado nutricional y la acumulación de N y Si en las hojas y tallos de la caña de azúcar, pero la producción de tallos fue menor al usar silicato, comparado con cal.

Palabras clave: Saccharum spp., fertilización nitrogenada, silicato, cal, producción de tallos.

 

INTRODUCTION

Cultivation of sugar cane (Saccharum spp.) has increased in Brazil as a result of technological improvements (Orlando Filho et al., 1996) such as soil fertilization and liming (Korndorfer and Martens, 1992). In order to increase the efficiency of fertilizers, soil acidity correction practices are fundamental. Soil acidity is corrected by lime applications, but alternative correction materials are considered, such as metallurgy scoria which is an industrial residue. These products correct soil acidity, and also supply the plants with Ca, Mg, and Si (Prado and Fernandes, 2000). In highly productive systems, soil acidity correction practices also increase the efficiency of N fertilization (Deren et al., 1994).

Nitrogen is an important in nutrition, growth, and productivity of ratoon sugarcane crops at harvest (Vitti et al., 2007), but with different doses of N (Korndorfer et al., 2002; Salgado-García et al., 2000). Sugar cane crops also respond favorably to fertilization with Si, particularly in Si deficient soils. Experiments carried out in Brazil using silicate show consistent results, with production increasing from 11 to 20 % (Datnoff et al., 2001). Studies with N and silicate fertilization show that Si may optimize the highest N efficiency when sugarcane is grown in highly productive systems.

The Si effect tends to be more beneficial to crops with high N doses (Takahashi, 1995), because it protects tender tissues from penetration by external agents, like plagues and pathogens, and reduces self-shading in the field, which maintains optimal photosynthetic rates (Malavolta, 2006a). Si makes the leaves more erect, reduces lodging, and increases the fertilization response, mainly when N is used (Malavolta, 2006b).

Few studies investigated the relationship between N and Si, and most of them were carried out under greenhouse conditions (Basto et al., 2010; Vale et al., 2010). Field studies have been restricted to the first cycles (Fonseca, 2011) of the cane crop (Borges, 2012). Therefore, solid information concerning the effects of N-Si interactions along the sugarcane ratoon is necessary.

Thus, the aim of this research was to evaluate the soil chemical characteristics, nutritional status, nutrient accumulation, and stalk production in a fourth ratoon sugarcane crop, in response to N, Si, and liming applications.

 

MATERIALS AND METHODS

The field experiment was carried out from July 2012 to July 2013 at the UNESP experimental farm (21° 14' 05'' S and 48° 17' 09'' W), Jaboticabal campus, state of São Paulo (SP), Brazil. The soil of the experimental area was classified as a distrophic Red Latosol (Embrapa, 2013). Total precipitation during the experiment was abundant (1407 mm) and adequately distributed (Figure 1).

After harvesting the third ratoon crop, which received silicate (S) and lime (L) at tillering, the soil chemical analysis was performed for fertility purposes, in the 0-20 cm deep layer, where S and L were applied, according to Raij et al. (2001). Soil fertility characteristics were: pH (CaCL₂): 4.3 and 4.4; OM: 14.7 and 14.5 g dm^-3; P-resin: 10.2 and 9.7 mg dm^-3; K: 1.1 and 1.1 mmol_c dm^-3; Ca: 11.0 and 12.0 mmol_c dm^-3; Mg: 4.3 and 4.3 mmol_c dm^-3; H + Al: 43.6 and 42.4 mmol_c dm^-3; sum of cations (SB): 16.5 and 17.4 mmol_c dm^-3, cation exchange capacity (CEC): 60.1 and 59.6 mmol_c dm^-3, and base saturation (BS): 27 % and 29 %; N-NH₄+: 0.3 and 0.3 mg kg^-1; N-NO₃^-: 0.4 and 0.4 mg kg^-1 (Tedesco et al., 1985) and Si: 0.8 and 0.7 mg dm^-3 (Korndorfer et al., 2004).

The experiment was arranged in the field according to a completely randomized block design in a 5 x 2 factorial arragement (five doses of N: 0, 40, 80, 120, and 160 kg ha^-1; and two corrective materials: S and L), with four replications per treatment. Each experimental plot consisted of 4 6 m long furrows with 1.5 m between them, accounting for a total area of 36 m². In each plot, the sampling area included the two central rows, excluding the 1 m row hedges between each row; total sampling area was 18 m².

The experiment was carried out in the fourth ratoon sugarcane crop using the RB85551156 variety. This variety is early ripening, has excellent budding, high yield, and is the seventh most cultivated sugarcane variety in São Paulo, Mato Grosso, and Mato Grosso do Sul states, and cultivation area is likely to increase (PMGCA, 2009). The sugarcane planting and ratoon growth information, as well as its agronomic management were reported by Fonseca (2011) and Borges (2012).

Prior to the establishment of the experiment, the corrective doses were determined to raise BS to 60 % according to the recommendations for growing sugarcane in SP. However, only half of the amount was used, because the L was applied superficially, without incorporation (Rossetto et al., 2004). Lime was applied at a dose of 1.0 t ha^-1 (relative efficiency (RE) = 86.2 %, reactivity (R) = 85.9 %, CaO = 41.4 %, and MgO = 10.6 %); and Si_at a dose of 0.91 t ha^-1 (RE = 88.0 %, R = 82.9 %, CaO = 42.1 %, MgO = 12.4 %, total Si = 8.1 %, soluble Si (in Na₂CO₃ + NH₄NO₃) = 6.0%).

To set the N doses, a base dose of 120 kg ha^-1 N was used, which is recommended for attaining ratoon sugarcane production higher than 100 t ha^-1 in SP (Spironello et al., 1997). Nitrogen fertilizer was locally applied, without incorporation, before the rainy period of July 2012. This fertilizer was applied as urea, manually distributed 15 d after sugarcane sprouting, at 10 cm from the planting line. K was KCl-type, applied uniformly in all treatments, concurrently as N at a concentration of 150 kg ha^-1 of K₂O (Spironello et al., 1997). There was no P fertilization.

During the experiment (6 and 12 months after sugarcane sprouting) soil samples were taken at the locations where the fertilizers were applied in order to determine N (N-NH₄⁺ and N-NO₃^-) and Si contents. Ten samples were taken from each plot at depths of 0-10, 10-20, 20-40, and 40-60 cm. The soil samples used for the determination of N were transported from the field to the laboratory in thermal boxes with ice (Mattos Júnior et al., 1995). In the laboratory, the samples were kept in a freezer until they were used for the determination of N-NH₄⁺ and N-NO₃^- (Tedesco et al., 1985). The analytical determination of the "available" Si concentration in the soil followed procedures described by Korndorfer et al. (2004).

At nine months, the highest sugarcane vegetative development phase, the N and Si foliar content were measured, from 10 leaf samples 20 cm center, leaf +1, without the central midrib (Raij and Cantarella, 1997). Analysis of N and Si were performed according to Bataglia et al. (1983) and Korndörfer et al. (2004), respectively.

Twelve months after sugarcane sprouting, manual harvesting of the plants took place without previous burning of the plants. The stalks weight was expressed in t ha^-1. To calculate N and Si content as kg of dry matter produced, total leaves and stalks in the sampling area were weighed separately.

Analysis of variance was used for all data, based on the F test (p≤0.05). Means comparisons of corrective treatments were performed by the Tukey test (p≤0.05). When N dose variation was significantly different, polynomial regression analysis was performed. SISVAR was used for all statistical analyses (version 5.3 BETA; Ferreira, 2011).

 

RESULTS AND DISCUSSION

There was a significant effect of N fertilization on the soil N-NH₄⁺ concentration at 6 and 12 months of sugarcane growth. At 12 months, a corrective effect on the soil N-NH₄⁺ concentration was observed (Table 1). This result is similar to that observed by Vale et al. (2013) when they studied N-NH₄⁺ and N-NH₃^- content in soil as a function of N application in sugarcane ratoons. Améndola-Massiotti et al. (2011) also found an increase in N content in the soil with increasing doses of N.

The N doses associated with S and L addition influenced the amount of N-NO₃^- in the soil at six months after sugarcane sprouting. However, at 12 months, the effect of N doses and corrective materials only increased soil N-NO₃^- when S was used (Table 1). These results are similar to those observed at six months by Fonseca (2011) who found an interaction between N and corrective additions with soil N-NO₃^- in a similar experiment in the first growth stage. Regarding Si content, the N doses associated with corrective material additions influenced the Si content in the soil at 6 and 12 months after sugarcane sprouting (Table 1). These results are similar to those observed by Fonseca (2011).

Nitrogen application had both a linear and quadratic relationship with soil N-NH₄⁺ at 6 and 12 months after sugarcane sprouting, independent of the corrective materials used (Figure 2). The sugarcane response to N application was possibly due to the low amount of N-NH₄⁺ in the soil (0.3 mg kg^-1) after the third ratoon harvest. Vale et al. (2013) also found a linear relationship between N addition rate and soil N-NH/levels six months after sugarcane sprouting.

Nitrogen fertilization rates, when associated with corrective material addition, had a quadratic relationship with soil N-NO₃^- at six months after sugarcane sprouting (Figure 3A). At 12 months, independent of the corrective materials used, N fertilization promoted an increase of N-NO₃^- in the soil (Figure 3B). The N-NO₃^- value found in this experiment was higher than the one reported by Fonseca (2011) at 12 months after sugarcane sprouting, which may have been caused by different N fertilization management for sugarcane in the first growth cycle.

The application of increasing N doses in association with soil corrective materials had a linear relationship with soil Si concentration in the soil six months after the sprouting of sugarcane plants. There was no significant effect of silicate fertilization on soil Si concentration (Figure 4A).

Measurements made 12 months after plant sprouting, showed a quadratic relationship between increasing doses of N with S addition and Si content in the soil. Besides, L had no significant influence on soil Si content (Figure 4B). Sousa et al. (2010) also applied S to sugarcane and observed that the soil Si concentration increased linearly when the residue doses increased at 120 and 260 d.

Nitrogen and corrective material addition interacted to influence leaf content, the accumulation of N and Si in leaves and stalks, and stalk production (Table 2). These results are similar to those obtained by Fonseca (2011) for N and Si content and N accumulation, and by Borges (2012) for N in leaves and Si in leaves and stalks.

Regarding stalk production, Reis et al. (2013) showed an increase in sugarcane stalk production in response to corrective material additions. Castro et al. (2014) studied N fertilization on growth of the SP81-3250 sugarcane variety and observed higher stalk production at 144 N kg ha^-1.

Doses of N doses in association with corrective material additions had a quadratic relationship with leaf N content (Figure 5A). The interaction between N and corrective materials led to adequate levels of N (18-25 g kg^-1) according to Raij and Cantarella (1997). The leaf N levels observed in our study were higher than those reported by a similar experiment in the first sugarcane cycle. The lower level of N found by Fonseca (2011) was probably due to the low response of the cane plant to N fertilization (Orlando Filho, 1994).

The interaction between N and the corrective material additions had a quadratic relationship with leaf Si concentration (Figure 5B). Anderson and Bowen (1992) found that in order to obtain high sugarcane stalk production, Si should be added at concentrations greater than 10 g kg^-1 of + 1 leaf dry matter.

Increasing N doses along with the use of S and L showed a quadratic relationship with N and Si accumulation leaves (Figure 5C, D). The results from this experiment contrast those of Borges (2012), who found that N accumulation was higher when S was used in association with increasing N doses. This difference may be due to the different production cycles in the two experiments. However, other studies show an increase in Si uptake by sugarcane plants when S was applied (Anderson, 1991; Raid et al., 1992). Silicon increases in the leaf may be due to Si increases in the soil brought about by silicate.

The increasing N doses, when applied with the corrective materials, showed a quadratic relationship with the accumulation of N and Si in the stalks (Figure 6A, B). These results for N are different than those reported by Fonseca (2011), who observed a high accumulation of N when the silicate was applied to the soil. For Si, a higher value was observed by Fonseca (2011), where Si accumulation in the stalks using corrective materials was 96.4 kg ha^-1. The higher Si accumulation in the stalks observed by Fonseca (2011) may be due to the application of 2.61 t ha^-1 of Ca and Mg silicate, whereas in our study fertilizer was applied superficially without incorporation (0.9 t ha^-1 of Ca and Mg silicate).

Nitrogen doses applied with corrective materials showed a quadratic relationship with stalk production (Figure 6C). These results are similar to those reported by Rosseto (2004) who studied the effect of L on sugarcane stem production. But Fonseca (2011) observed a linear increasing relationship with stalk production when silicate was applied. The smaller effect on stalk production when silicate was applied may be due to higher N accumulation in leaves and stalks when L was used (Figures 5C and 6A). This explains the higher production in this treatment because N promotes an increase in stalk production (Vieira et al., 2010). However, it could also be due to the absence of stress during the cultivation of sugarcane, as there was ample water available during crop development, and no pests and disease damage were observed. Silicon is a beneficial element and its positive effect was reported under stressful conditions (Marschner, 1986).

 

CONCLUSION

Nitrogen fertilization associated with the use of S and line increased the levels of N-NO₃^- and Si in the soil, promoting improvements in the nutritional status of sugarcane and accumulation of N and Si in the leaves and stalks. However, stalk production was lower when using S than when using limestone.

 

ACKNOWLEDGMENTS

We would like to thank FAPESP (São Paulo State Foundation for the Financial Support of Research) for financially supporting the project and to CAPES (Coordination for the Support of People engaged in University Teaching) for the scholarship awarded to the first author.

 

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