The Role of Nitrogen Fertilizers in Sugarcane Root Biomass under Field Conditions
Author(s)
Rafael Otto1*,
Henrique Coutinho Junqueira Franco2,
Carlos Eduardo Faroni3,
André Cesar Vitti4,
Emídio Cantidio Almeida de Oliveira5,
Renata Alcarde Sermarini6,
Paulo Cesar Ocheuze Trivelin7
Affiliation(s)
1 Department of Soil Science, Luiz de Queiroz College of Agriculture, University of Sao Paulo, Piracicaba, Brazil. 2 Brazilian Bioethanol Science and Technology Laboratory (CTBE), Rua Giuseppe Maximo Scolfaro, Campinas, Brazil. 3 Sugarcane Research Center (CTC), Piracicaba, Brazil. 4 Sao Paulo Agency of Agribusiness and Technology (APTA), Piracicaba, Brazil. 5 Federal Rural University of Pernambuco (UFRPE), Recife, Brazil. 6 Department of Exact Sciences, Luiz de Queiroz College of Agriculture, University of Sao Paulo, Piracicaba, Brazil. 7 Center for Nuclear Energy in Agriculture, University of Sao Paulo, Piracicaba, Brazil.
1 Department of Soil Science, Luiz de Queiroz College of Agriculture, University of Sao Paulo, Piracicaba, Brazil. 2 Brazilian Bioethanol Science and Technology Laboratory (CTBE), Rua Giuseppe Maximo Scolfaro, Campinas, Brazil. 3 Sugarcane Research Center (CTC), Piracicaba, Brazil. 4 Sao Paulo Agency of Agribusiness and Technology (APTA), Piracicaba, Brazil. 5 Federal Rural University of Pernambuco (UFRPE), Recife, Brazil. 6 Department of Exact Sciences, Luiz de Queiroz College of Agriculture, University of Sao Paulo, Piracicaba, Brazil. 7 Center for Nuclear Energy in Agriculture, University of Sao Paulo, Piracicaba, Brazil.
ABSTRACT
Sugarcane is used worldwide for sugar, ethanol and energy production. In Brazil, the shift from burned to unburned harvest systems resulted in increases in nitrogen fertilization rates, which can impact root architecture and biomass. The expectation is also an increase in sugarcane biomass. The study hypothesized that high N rates applied to sugarcane fields increases root growth and N stored in roots, promoting higher biomass and N accumulated in shoots. Two experiments were set up in Southeastern Brazil, on a Typic Kandiudox (TK) and Rhodic Eutrudox (RE). Four treatments were studied 1) N application in the plant-cane (0 and 120 kg·ha-1 N) and 2) N application in the ratoon (0 and 150 kg·ha-1 N). The shoot biomass and the root density (by the core method up to 0.6 m) were evaluated over the first ratoon crop cycle, and the N content in those compartments was also examined. There was no carry over effect on N applied at planting in root and shoot biomass in the ratoon crop cycle. At the RE site, the ratoon N fertilization increased root density in the superficial soil layer (0 - 0.2 m) and close to the plants (<0.3 m). The effect of N addition on root biomass, and biomass and N accumulated in shoot was limited in both sites. Increasing N rates in unburned sugarcane fields do not consistently increases root and shoot biomass under Brazilian field conditions.
Sugarcane is used worldwide for sugar, ethanol and energy production. In Brazil, the shift from burned to unburned harvest systems resulted in increases in nitrogen fertilization rates, which can impact root architecture and biomass. The expectation is also an increase in sugarcane biomass. The study hypothesized that high N rates applied to sugarcane fields increases root growth and N stored in roots, promoting higher biomass and N accumulated in shoots. Two experiments were set up in Southeastern Brazil, on a Typic Kandiudox (TK) and Rhodic Eutrudox (RE). Four treatments were studied 1) N application in the plant-cane (0 and 120 kg·ha-1 N) and 2) N application in the ratoon (0 and 150 kg·ha-1 N). The shoot biomass and the root density (by the core method up to 0.6 m) were evaluated over the first ratoon crop cycle, and the N content in those compartments was also examined. There was no carry over effect on N applied at planting in root and shoot biomass in the ratoon crop cycle. At the RE site, the ratoon N fertilization increased root density in the superficial soil layer (0 - 0.2 m) and close to the plants (<0.3 m). The effect of N addition on root biomass, and biomass and N accumulated in shoot was limited in both sites. Increasing N rates in unburned sugarcane fields do not consistently increases root and shoot biomass under Brazilian field conditions.
Cite this paper
Otto, R. , Franco, H. , Faroni, C. , Vitti, A. , Oliveira, E. , Sermarini, R. and Trivelin, P. (2014) The Role of Nitrogen Fertilizers in Sugarcane Root Biomass under Field Conditions. Agricultural Sciences, 5, 1527-1538. doi: 10.4236/as.2014.514164.
Otto, R. , Franco, H. , Faroni, C. , Vitti, A. , Oliveira, E. , Sermarini, R. and Trivelin, P. (2014) The Role of Nitrogen Fertilizers in Sugarcane Root Biomass under Field Conditions. Agricultural Sciences, 5, 1527-1538. doi: 10.4236/as.2014.514164.
References
[1] Vries, S.C., van de Vem, G.W.J., van Ittersum, M.K. and Giller, K.E. (2010) Resource Use Efficiency and Environmental Performance of Nine Major Biofuel Crops, Processed by First-Generation Conversion Techniques. Biomass and Bioenergy, 34, 588-601. http://dx.doi.org/10.1016/j.biombioe.2010.01.001 [2] FAOSTAT (2014) Food and Agriculture Organization of the United Nations.
http://faostat.fao.org/site/567/default.aspx#ancor [3] Smith, D.M., Inman-Bamber, N.G. and Thorburn, P.J. (2005) Growth and Function of the Sugarcane Root System. Field Crops Research, 92, 169-183. http://dx.doi.org/10.1016/j.fcr.2005.01.017 [4] Matsuoka, S. and Garcia, A.A.F. (2011) Sugarcane underground Organs: Going Deep for Sustainable Production. Tropical Plant Biology, 4, 22-30. http://dx.doi.org/10.1007/s12042-011-9076-3 [5] Chopart, J.L., Rodrigues, S.R., Azevedo, M.C.B. and Medina, C.C. (2009) Estimating Sugar-Cane Root Length Density through Root Maping and Orientation Modelling. Plant and Soil, 313, 101-112.
http://dx.doi.org/10.1007/s11104-008-9683-4 [6] Rossetto, R., Dias, F.L.F., Landell, M.G.A., Cantarella, H., Tavares, S., Vitti, A.C. and Perecin, D. (2010) N and K Fertilization of Sugarcane Ratoons Harvested without Burning. Proceedings of International Society Sugar Cane Technology, 27, 1-8. [7] Hutchings, M.J. and John, E.A. (2003) Distribution of Roots in Soil, and Root Foraging Activity. In: de Kroon, H. and Visser, E.J., Eds., Root Ecology, Springer-Verlag, Berlin, 33-60.
http://dx.doi.org/10.1007/978-3-662-09784-7_2 [8] Zhang, H.M., Rong, H. and Pilbeam, D. (2007) Signaling Mechanisms Underlying the Morphological Responses of the Root System to Nitrogen in Arabidopsis Thaliana. Journal of Experimental Botany, 58, 2329-2338. http://dx.doi.org/10.1093/jxb/erm114 [9] Jing, J., Rui, Y., Zhang, F., Rengel, Z. and Shen, J. (2010) Localized Application of Phosphorus and Ammonium Improves Growth of Maize Seedlings by Stimulating Root Proliferation and Rhizosphere Acidification. Field Crops Research, 119, 335-364. http://dx.doi.org/10.1016/j.fcr.2010.08.005 [10] Li, H., Zhang, F. and Shen, J. (2012) Contribution of Root Proliferation in Nutrient-Rich Soil Patches to Nutrient Uptake and Growth of Maize. Pedosphere, 22, 776-784.
http://dx.doi.org/10.1016/S1002-0160(12)60063-0 [11] Shen, J.B., Yuan, L.X., Zhang, J.L., Li, H.G., Bai, Z.H., Chen, X.P., Zhang, W.F. and Zhang, F.S. (2011) Phosphorus Dynamics: From Soil to Plant. Plant Physiology, 156, 997-1005.
http://dx.doi.org/10.1104/pp.111.175232 [12] Li, H., Ma, Q., Li, H., Zhang, F., Rengel, Z. and Shen, J. (2014) Root Morphological Responses to Localized Nutrient Supply Differ among Crop Species with Contrasting Root Traits. Plant and Soil, 376, 151-163. http://dx.doi.org/10.1007/s11104-013-1965-9 [13] Anderson, E.L. (1987) Corn Root Growth and Distribution as Influenced by Tillage and Nitrogen Fertilization. Agronomy Journal, 79, 544-549.
http://dx.doi.org/10.2134/agronj1987.00021962007900030029x [14] Anghinoni, I. and Barber, S.A. (1988) Corn Root Growth and Nitrogen Uptake as Affected by Ammonium Placement. Agronomy Journal, 80, 799-802.
http://dx.doi.org/10.2134/agronj1988.00021962008000050021x [15] Mackay, A.D. and Barber, S.A. (1986) Effect of Nitrogen on Root Growth of Two Corn Genotypes in the Field. Agronomy Journal, 78, 699-703.
http://dx.doi.org/10.2134/agronj1986.00021962007800040028x [16] Drew, M.C. (1975) Comparison of the Effects of a Localized Supply of Phosphate, Nitrate, Ammonium and Potassium on the Growth of the Seminal Root System, and the Shoot, in Barley. New Phytologist, 75, 479-490. http://dx.doi.org/10.1111/j.1469-8137.1975.tb01409.x [17] Otto, R., Franco, H.C.J., Faroni, C.E., Vitti, A.C. and Trivelin, P.C.O. (2009) Sugarcane Root and Shoot Phytomass Related to Nitrogen Fertilization at Planting. Pesquisa Agropecuária Brasileira, 44, 398-405. http://dx.doi.org/10.1590/S0100-204X2009000400010 [18] Sampaio, E.V.S.B., Salcedo, I.H. and Cavalcanti, F.J.A. (1987) Dinamica de nutrientes em cana-de-a?úcar. III: Conteúdo de nutrientes e distribuicao radicular no solo. Pesquisa Agropecuária Brasileira, 22, 425-431. [19] Thorburn, P.J., Dart, I.K., Biggs, I.M., Baillie, C.P., Smith, M.A. and Keating, B.A. (2003) The Fate of Nitrogen Applied to Sugarcane by Trickle Irrigation. Irrigation Science, 22, 201-209. http://dx.doi.org/10.1007/s00271-003-0086-2 [20] Vitti, A.C., Trivelin, P.C.O., Gava, G.J.C., Pennatti, C.P., Bologna, I.R., Faroni, C.E. and Franco, H.C.J. (2007) Produtividade da cana-de-acúcar relacionada ao nitrogênio residual da adubacao e do sistema radicular. Pesquisa Agropecuária Brasileira, 42, 249-256.
http://dx.doi.org/10.1590/S0100-204X2007000200014 [21] Soil Survey Staff (2010) Keys to Soil Taxonomy. 11th Edition, USDA-Natural Resources Conservation Service, Washington DC. [22] van Raij, B., Andrade, J.C., Cantarella, H. and Quaggio, J.A., Eds. (2001) Análise química para avalia??o da fertilidade de solos tropicais. Instituto Agron?mico, Campinas, 285 p. [23] Grossman, R.B. and Reinsch, T.G. (2002) Bulk Density and Linear Extensibility. In: Dane, J.H. and Topp, G.C., Eds., Methods of Soil Analysis: Physical Methods, Part 4, Soil Science Society of America, Madison, 201-228. [24] Dane, J.H. and Hopmans, J.W. (2002) Pressure Plate Extractor. In: Dane, J.H. and Topp, G.C., Eds., Methods of Soil Analysis: Physical Methods, Part 4, Soil Science Society of America, Madison, 688-690. [25] Otto, R., Trivelin, P.C.O., Franco, H.C.J., Faroni, C.E. and Vitti, A.C. (2009) Root System Distribution of Sugar Cane as Related to Nitrogen Fertilization, Evaluated by Two Methods: Monolith and Probes. Revista Brasileira de Ciência do Solo, 33, 601-611.
http://dx.doi.org/10.1590/S0100-06832009000300013 [26] Malavolta, E., Vitti, G.C. and Oliveira, S.A. (1997) Avaliacao do estado nutricional das plantas-princípios e aplicacoes. 2nd Edition, Potafós, Piracicaba, 309 p. [27] Allen, R.G., Pereira, L.S., Raes, D. and Smith, M. (1998) Crop Evapotranspiration: Guidelines for Computing Crop Water Requirements. FAO Irrigation and Drainage Paper 56, FAO, Rome, 300 p. [28] Battie-Laclau, P. and Laclau, J.P. (2009) Growth of the Whole Root System for a Plant Crop of Sugarcane under Rainfed and Irrigated Environments in Brazil. Field Crops Research, 114, 351-360.
http://dx.doi.org/10.1016/j.fcr.2009.09.004 [29] Ball-Coelho, B., Sampaio, E.V.S.B., Tiessen, H. and Stewart, J.W.B. (1992) Root Dynamics in Plant and Ratoon Crops of Sugar Cane. Plant and Soil, 142, 297-305. http://dx.doi.org/10.1007/BF00010975 [30] Imhoff, S., Kay, B.D., Silva, A.P. and Hajabbasi, M.A. (2010) Evaluating Responses of Maize (Zea mays L.) to Soil Physical Conditions Using a Boundary Line Approach. Soil and Tillage Research, 106, 303-310. http://dx.doi.org/10.1016/j.still.2009.11.007 [31] Otto, R., Silva, A.P., Franco, H.C.J., Oliveira, E.C.A. and Trivelin, P.C.O. (2011) High Soil Penetration Resistance Reduces Sugarcane Root System Development. Soil and Tillage Research, 117, 201-210.
http://dx.doi.org/10.1016/j.still.2011.10.005 [32] Aboyami, Y.A. (1989) Effect of Soil Type and Crop Cycle on Root Development and Distribution Pattern of a Commercial Sugarcane Cultivar under Normal Irrigation and Field Conditions at Bacita Estate, Nigeria. Turrialba, 39, 78-84. [33] Franco, H.C.J., Otto, R., Faroni, C.E., Vitti, A.C., Oliveira, E.C.A. and Trivelin, P.C.O. (2011) Nitrogen in Sugarcane Derived from Fertilizer under Brazilian Field Conditions. Field Crops Research, 121, 29-41.
http://dx.doi.org/10.1016/j.fcr.2010.11.011 [34] Dourado-Neto, D., Powlson, D., Abu Bakar, R., Bacchi, O.O.S., Basanta, M.V., thi Cong, P., et al. (2010) Multiseason Recoveries of Organic and Inorganic Nitrogen-15 in Tropical Cropping Systems. Soil Science Society of America Journal, 74, 139-152. http://dx.doi.org/10.2136/sssaj2009.0192 [35] Smith, J.P. (1998) Studies on the Relation between Root Growth and Shoot Growth of Sugarcane. Ph.D. Thesis, James Cook University, Queensland.
[1] Vries, S.C., van de Vem, G.W.J., van Ittersum, M.K. and Giller, K.E. (2010) Resource Use Efficiency and Environmental Performance of Nine Major Biofuel Crops, Processed by First-Generation Conversion Techniques. Biomass and Bioenergy, 34, 588-601. http://dx.doi.org/10.1016/j.biombioe.2010.01.001 [2] FAOSTAT (2014) Food and Agriculture Organization of the United Nations.
http://faostat.fao.org/site/567/default.aspx#ancor [3] Smith, D.M., Inman-Bamber, N.G. and Thorburn, P.J. (2005) Growth and Function of the Sugarcane Root System. Field Crops Research, 92, 169-183. http://dx.doi.org/10.1016/j.fcr.2005.01.017 [4] Matsuoka, S. and Garcia, A.A.F. (2011) Sugarcane underground Organs: Going Deep for Sustainable Production. Tropical Plant Biology, 4, 22-30. http://dx.doi.org/10.1007/s12042-011-9076-3 [5] Chopart, J.L., Rodrigues, S.R., Azevedo, M.C.B. and Medina, C.C. (2009) Estimating Sugar-Cane Root Length Density through Root Maping and Orientation Modelling. Plant and Soil, 313, 101-112.
http://dx.doi.org/10.1007/s11104-008-9683-4 [6] Rossetto, R., Dias, F.L.F., Landell, M.G.A., Cantarella, H., Tavares, S., Vitti, A.C. and Perecin, D. (2010) N and K Fertilization of Sugarcane Ratoons Harvested without Burning. Proceedings of International Society Sugar Cane Technology, 27, 1-8. [7] Hutchings, M.J. and John, E.A. (2003) Distribution of Roots in Soil, and Root Foraging Activity. In: de Kroon, H. and Visser, E.J., Eds., Root Ecology, Springer-Verlag, Berlin, 33-60.
http://dx.doi.org/10.1007/978-3-662-09784-7_2 [8] Zhang, H.M., Rong, H. and Pilbeam, D. (2007) Signaling Mechanisms Underlying the Morphological Responses of the Root System to Nitrogen in Arabidopsis Thaliana. Journal of Experimental Botany, 58, 2329-2338. http://dx.doi.org/10.1093/jxb/erm114 [9] Jing, J., Rui, Y., Zhang, F., Rengel, Z. and Shen, J. (2010) Localized Application of Phosphorus and Ammonium Improves Growth of Maize Seedlings by Stimulating Root Proliferation and Rhizosphere Acidification. Field Crops Research, 119, 335-364. http://dx.doi.org/10.1016/j.fcr.2010.08.005 [10] Li, H., Zhang, F. and Shen, J. (2012) Contribution of Root Proliferation in Nutrient-Rich Soil Patches to Nutrient Uptake and Growth of Maize. Pedosphere, 22, 776-784.
http://dx.doi.org/10.1016/S1002-0160(12)60063-0 [11] Shen, J.B., Yuan, L.X., Zhang, J.L., Li, H.G., Bai, Z.H., Chen, X.P., Zhang, W.F. and Zhang, F.S. (2011) Phosphorus Dynamics: From Soil to Plant. Plant Physiology, 156, 997-1005.
http://dx.doi.org/10.1104/pp.111.175232 [12] Li, H., Ma, Q., Li, H., Zhang, F., Rengel, Z. and Shen, J. (2014) Root Morphological Responses to Localized Nutrient Supply Differ among Crop Species with Contrasting Root Traits. Plant and Soil, 376, 151-163. http://dx.doi.org/10.1007/s11104-013-1965-9 [13] Anderson, E.L. (1987) Corn Root Growth and Distribution as Influenced by Tillage and Nitrogen Fertilization. Agronomy Journal, 79, 544-549.
http://dx.doi.org/10.2134/agronj1987.00021962007900030029x [14] Anghinoni, I. and Barber, S.A. (1988) Corn Root Growth and Nitrogen Uptake as Affected by Ammonium Placement. Agronomy Journal, 80, 799-802.
http://dx.doi.org/10.2134/agronj1988.00021962008000050021x [15] Mackay, A.D. and Barber, S.A. (1986) Effect of Nitrogen on Root Growth of Two Corn Genotypes in the Field. Agronomy Journal, 78, 699-703.
http://dx.doi.org/10.2134/agronj1986.00021962007800040028x [16] Drew, M.C. (1975) Comparison of the Effects of a Localized Supply of Phosphate, Nitrate, Ammonium and Potassium on the Growth of the Seminal Root System, and the Shoot, in Barley. New Phytologist, 75, 479-490. http://dx.doi.org/10.1111/j.1469-8137.1975.tb01409.x [17] Otto, R., Franco, H.C.J., Faroni, C.E., Vitti, A.C. and Trivelin, P.C.O. (2009) Sugarcane Root and Shoot Phytomass Related to Nitrogen Fertilization at Planting. Pesquisa Agropecuária Brasileira, 44, 398-405. http://dx.doi.org/10.1590/S0100-204X2009000400010 [18] Sampaio, E.V.S.B., Salcedo, I.H. and Cavalcanti, F.J.A. (1987) Dinamica de nutrientes em cana-de-a?úcar. III: Conteúdo de nutrientes e distribuicao radicular no solo. Pesquisa Agropecuária Brasileira, 22, 425-431. [19] Thorburn, P.J., Dart, I.K., Biggs, I.M., Baillie, C.P., Smith, M.A. and Keating, B.A. (2003) The Fate of Nitrogen Applied to Sugarcane by Trickle Irrigation. Irrigation Science, 22, 201-209. http://dx.doi.org/10.1007/s00271-003-0086-2 [20] Vitti, A.C., Trivelin, P.C.O., Gava, G.J.C., Pennatti, C.P., Bologna, I.R., Faroni, C.E. and Franco, H.C.J. (2007) Produtividade da cana-de-acúcar relacionada ao nitrogênio residual da adubacao e do sistema radicular. Pesquisa Agropecuária Brasileira, 42, 249-256.
http://dx.doi.org/10.1590/S0100-204X2007000200014 [21] Soil Survey Staff (2010) Keys to Soil Taxonomy. 11th Edition, USDA-Natural Resources Conservation Service, Washington DC. [22] van Raij, B., Andrade, J.C., Cantarella, H. and Quaggio, J.A., Eds. (2001) Análise química para avalia??o da fertilidade de solos tropicais. Instituto Agron?mico, Campinas, 285 p. [23] Grossman, R.B. and Reinsch, T.G. (2002) Bulk Density and Linear Extensibility. In: Dane, J.H. and Topp, G.C., Eds., Methods of Soil Analysis: Physical Methods, Part 4, Soil Science Society of America, Madison, 201-228. [24] Dane, J.H. and Hopmans, J.W. (2002) Pressure Plate Extractor. In: Dane, J.H. and Topp, G.C., Eds., Methods of Soil Analysis: Physical Methods, Part 4, Soil Science Society of America, Madison, 688-690. [25] Otto, R., Trivelin, P.C.O., Franco, H.C.J., Faroni, C.E. and Vitti, A.C. (2009) Root System Distribution of Sugar Cane as Related to Nitrogen Fertilization, Evaluated by Two Methods: Monolith and Probes. Revista Brasileira de Ciência do Solo, 33, 601-611.
http://dx.doi.org/10.1590/S0100-06832009000300013 [26] Malavolta, E., Vitti, G.C. and Oliveira, S.A. (1997) Avaliacao do estado nutricional das plantas-princípios e aplicacoes. 2nd Edition, Potafós, Piracicaba, 309 p. [27] Allen, R.G., Pereira, L.S., Raes, D. and Smith, M. (1998) Crop Evapotranspiration: Guidelines for Computing Crop Water Requirements. FAO Irrigation and Drainage Paper 56, FAO, Rome, 300 p. [28] Battie-Laclau, P. and Laclau, J.P. (2009) Growth of the Whole Root System for a Plant Crop of Sugarcane under Rainfed and Irrigated Environments in Brazil. Field Crops Research, 114, 351-360.
http://dx.doi.org/10.1016/j.fcr.2009.09.004 [29] Ball-Coelho, B., Sampaio, E.V.S.B., Tiessen, H. and Stewart, J.W.B. (1992) Root Dynamics in Plant and Ratoon Crops of Sugar Cane. Plant and Soil, 142, 297-305. http://dx.doi.org/10.1007/BF00010975 [30] Imhoff, S., Kay, B.D., Silva, A.P. and Hajabbasi, M.A. (2010) Evaluating Responses of Maize (Zea mays L.) to Soil Physical Conditions Using a Boundary Line Approach. Soil and Tillage Research, 106, 303-310. http://dx.doi.org/10.1016/j.still.2009.11.007 [31] Otto, R., Silva, A.P., Franco, H.C.J., Oliveira, E.C.A. and Trivelin, P.C.O. (2011) High Soil Penetration Resistance Reduces Sugarcane Root System Development. Soil and Tillage Research, 117, 201-210.
http://dx.doi.org/10.1016/j.still.2011.10.005 [32] Aboyami, Y.A. (1989) Effect of Soil Type and Crop Cycle on Root Development and Distribution Pattern of a Commercial Sugarcane Cultivar under Normal Irrigation and Field Conditions at Bacita Estate, Nigeria. Turrialba, 39, 78-84. [33] Franco, H.C.J., Otto, R., Faroni, C.E., Vitti, A.C., Oliveira, E.C.A. and Trivelin, P.C.O. (2011) Nitrogen in Sugarcane Derived from Fertilizer under Brazilian Field Conditions. Field Crops Research, 121, 29-41.
http://dx.doi.org/10.1016/j.fcr.2010.11.011 [34] Dourado-Neto, D., Powlson, D., Abu Bakar, R., Bacchi, O.O.S., Basanta, M.V., thi Cong, P., et al. (2010) Multiseason Recoveries of Organic and Inorganic Nitrogen-15 in Tropical Cropping Systems. Soil Science Society of America Journal, 74, 139-152. http://dx.doi.org/10.2136/sssaj2009.0192 [35] Smith, J.P. (1998) Studies on the Relation between Root Growth and Shoot Growth of Sugarcane. Ph.D. Thesis, James Cook University, Queensland.