Sugar cane had higher yield when established from node cuttings rather than from long stems and had a higher sugar content when the soil was amended with biochar

Chittakone Insixiengmai, Nguyen Nhut Xuan Dung¹ and T R Preston²

Faculty of Agriculture and Environment, Savannakhet University, Lao PDR
Lay_sku@yahoo.com
¹ Cantho University, Cantho, Vietnam
² Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria (CIPAV), Carrera 25 No 6-62 Cali, Colombia

Abstract

This study compared planting method (long stems or node sections) of sugar cane and addition of biochar to the soil. The design was a 2*2 factorial with 4 replications in a split-lot design. Planting method was the main plot; addition of biochar (2 kg/m²) was the sub-plot. Individual plots were 4*4m. For node cultivation, stem sections of 5cm including one node were cultivated in plastic bags in a nursery and, after 28 days, transplanted to the field.

Planting sugar cane from node sections rather than long stems increased: stem yields, the number of stems/ha but had no effect on the Brix (sugar content) of the juice. Adding biochar to the soil increased stem yield, number of leaves, the height of the growing point and the Brix of the juice, but had no effect on the number of stems per ha. Addition of biochar to the soil increased pH, organic matter, N content and water holding capacity. There was no effect of planting method on these criteria.

Keywords: brix, pH, organic matter, nitrogen

Introduction

Sugar cane is an important economic crop that is grown in most tropical countries. In Lao PDR sugar cane is planted on 200,000 ha. In Savannakhet province there are two sugar factories. The Mithphone factory is located in Kanghad village, Xaybouli district on an area of 10,000 ha. The yield of sugarcane is 1.5 million tonnes per year. The second factory is the Savan sugar factory located in Lianxay village where the concession area is 5000ha. Yields are low (less than 60 tonnes/ha/year) and the cane has to be re-planted every 3 to 4 years. Major constraints are the acid soils (pH 4.5) and low content of organic matter.

A new method of planting sugar cane has been developed in India and applied in several countries in the Caribbean. The method is known as the “Sustainable Sugarcane Initiative, SSI” (Gujja et al 2009). The method consists of an innovative set of agronomic practices, with a reduced ecological footprint. It has spread very fast among the sugarcane growers in India. The SSI will most likely become the standard planting method owing to its yield advantage, reduced use of water and other inputs.

The SSI innovation can give benefits such as yield improvement of 20-50% (depending on location, conditions and other factors), better germination of seed material, reduced plant mortality rate, intercultural operations carried out easily due to wider spacing, more accessibility to air and sunlight, increase in length and weight of each cane, and a shorter time to harvest. In this planting system only the nodes are planted, first in a nursery and then transplanted to the field.

Biochar is the carbon-rich residue obtained by combustion of fibrous biomass in oxygen-restricted conditions, which is utilized for soil amendment (Preston 2015) and for long term carbon sequestration (Lehmann 2007). Biochar has been reported to boost soil fertility and improve soil quality by raising soil pH, increasing moisture holding capacity, a ttracting more beneficial fungi and microbes, improving cation exchange capacity (CEC), and retaining nutrients in the soil (Lehmann and Joseph 2015). According to Zheng et al (2010), the use of nitrogenous fertilizer can be reduced when the soil is amended with biochar, due to its negative surface charge, facilitating strong adsorption of NH₄⁺. Thus, its addition to soils is expected to improve the retention and availability of ammonium salts to the plants.

For these reasons, it was proposed to study the yield of sugarcane established by the new method of planting, so as to improve sugar cane production for farmers. The effect of amending the soil with biochar was also investigated as a preliminary experiment indicated improved germination of sugar cane when biochar was added to the soil before planting (Chittakone 2015).

Hypotheses

It was hypothesized that establishing sugar cane from nodes rather than stems, and application of biochar to the soil, would increase biomass yield and sugar content.

Materials and methods

Location and duration

The experiment was conducted from March 2016 to February 2017 in the experimental farm of the Savannakhet University campus located in Nongphue village, Kaisonphomviharn district, Savannakhet province (middle part of Laos).

Treatments and experimental design

Two factors were compared:

Planting method: Nodes (N) or long stem (S)

Biochar: No application of biochar (NoBIOC) or 2 kg biochar per m ² (BIOC)

The design was a split-plot arrangement with 4 replications.

Main plot: node planting and stem planting

Sub plot: biochar and no biochar

Individual plots were 4*4m with space of 0.4m between plots.

Polybag preparation for node planting

Polybags (size 12 x 25 cm). were filled with a mixture of soil, biochar and pig manure (proportions of 2:1:0.2).

Sugarcane variety preparation

Sugarcane was propagated by cutting vegetative stalks into pieces called ‘sets’ containing a single node. The nodes were germinated in the polybag (called node planting of sugarcane). The ‘set’ was a section of stem about 2.5 cm either side of the node, and was cut with a sharp knife. The single node was germinated in the polybag for 28 days. Urrigation was given to the nursery throughout the whole period before transplantation of the settlings to the main field. Other cultural operations like weeding, rouging of diseased and pest infected settlings were done to maintain healthy settlings. Leaf clipping was done prior to transplanting into the main field to reduce the transpiration loss of water. Before transplanting water was added to the soil to provide sufficient moisture in the soil media.

For this treatment, sugarcane was propagated by cutting vegetative stalk into pieces of about 50-60 cm for direct planting in the field.

Soil management

As the experimental area was previously in forest, there was a need first to clear the secondary growth. The soil was ploughed two times. The first ploughing was about 20-25 cm deep after which the soil was left for the action of sun to get rid of insects and weeds. Seven days later, the soil was ploughed again. Then 16 plots each 4 x 4m were established.

Biochar

Biochar was prepared by burning rice husks in a “top-lit” gasifier stove at a temperature of 500-600 degree Celsius.

Sugar cane plant material

Sugar cane stems from a local variety (Khamphangsen52) were separated into long stems (50cm) (conventional planting method) or into sections of 5 cm including one node. On 17 March 2016, the nodes were planted in the nursery area, in plastic bags containing soil taken from the same area where the stems were planted. The long stems were planted in the experimental area at the same time as the nodes were planted in the nursery area. After 28 days the germinated nodes were transplanted onto the appropriate plots in the experimental area.

Planting method

After 28 days in the nursery, the germinated nodes were transplanted to the field. The germinated nodes were planted with 20cm between nodes, 20 cm deep and 80cm between rows.

After irrigating the soil, the long stems were laid in 20 cm deep trenches, maintaining a row distance of 80 cm. Planting was done at the same time as the nodes were established in the nursery.

Fertilization

All treatments were fertilized with urea (170 kg/ha) and di-ammonium phosphate (16-20-00) at 100 kg/ha. The DAP was applied before planting. Urea was applied the first time 58 days after planting the stems (30 days after transplanting the nodes) at the rate of 70kg/ha. The remaining 100 kg of urea were applied 5 months after planting.

Irrigation

In the main field, irrigation first was given after node transplanting and stem planting. Then supplementary irrigation was done during the first two months after planting; after which was the rainy season.

Data collection and measurements

Soil analysis

Soil samples were collected before planting and after harvest (10 months later). They were analyzed for total nitrogen, organic matter, pH and water holding capacity (AOAC1990).

Harvesting

The sugar cane was harvested 10 months after planting and separated into stems (from the base of the stem to the growing point), fresh and dead leaves. The content of sugar in the stem was determined by passing the whole stems through a 3-roll crusher and measuring the ‘brix” in a hand refractometer.

Statistical analysis

The data were analyzed using the General linear model (GLM) procedure in the ANOVA program of the Minitab software (Minitab 2016). Sources of variation were: planting method, biochar, interaction planting method*biochar and error.

Results and discussion

Composition of soil, biochar

The soil was low in organic matter and nitrogen and was acidic (Table 1).

Effect of biochar application and planting method on soil properties.

Addition of biochar to the soil increased pH, organic matter, N content and water holding capacity (Table 2; Figures 1, 2, 3 and 4). There was no effect of planting method on these criteria. These positive effects on soil fertility are in agreement with the report of Glaser et al (2002) who indicated that biochar added to soils not only changes its chemical properties but also affects physical properties such as soil water-holding and aggregation. These effects enhance water availability to crops and help to decrease erosion. The almost 100% increase in soil N, because of biochar addition, could be the result of reduced losses of nitrous oxides or increased fixation of N by soil organisms. Both these activities could be enhanced because of biochar support for biofilms that facilitate microbial action (Leng 2014).

Figure 1. Effect of biochar and planting method on soil pH	Figure 2. Effect of biochar and planting method on organic matter of soil
Figure 3. Effect of biochar and planting method on nitrogen content in the soil	Figure 4. Effect of biochar and planting method on water holding capacity

Effectof planting method (stem or node) and biochar addition on yield

Planting the sugar cane from node sections rather than long stems (Table 3) increased: stem yields by 24% (Figure 5), the number of stems by 37.5% (Figure 6)) and the number of leaves by 24% (Figure 7); but had no effect on the Brix (sugar content) of the juice. Adding biochar to the soil increased: stem yield by 5%, number of leaves by 4%, the height of the growing point by 11% and the Brix by 11%. Biochar had no effect on the number of stems per ha.

There are many reports of improvement in soil fertility, especially pH and water-holding capacity, when biochar is added to soils in amounts between 5 and 40 tonnes/ha, and that these changes are reflected in increased growth of vegetables and crop plants such as rice and maize (Preston 2015). There appear to be no reports on the effect of biochar on growth and yield of sugar cane. However, our finding that biochar increased the N content of soil planted with sugar cane is supported by the observation in Australia where reduced emissions of NO₂ were observed when biochar derived from sugar cane trash and bagasse was incorporated in the soil prior to planting of sugar cane (Quirk et al 2012).

Figure 5. Effect of biochar and planting method on the yield of sugarcane	Figure 6. Effect of biochar and planting method on the fresh leaves of sugarcane
Figure 7. Effect of biochar and planting method on dead leaves of sugarcane	Figure 8. Effect of biochar and planting method on height of sugarcane
Figure 9. Effect of biochar and planting method on the number of stems of sugarcane	Figure 10. Effect of biochar and planting method on the brix of the juice of sugarcane

Conclusions

• Addition of biochar to the soil increased pH, organic matter, N content and water holding capacity of the soil. There was no effect of planting method on these criteria.
  
  
• Planting the sugar cane from node sections rather than long stems increased: stem yields, the number of stems/ha but had no effect on the Brix (sugar content) of the juice.
  
  
• Adding biochar to the soil increased stem yield, number of leaves, the height of the growing point and the Brix of the juice, but had no effect on the number of stems per ha.

Acknowledgements

This research was done by the senior author as part of the requirements for the MSc degree in Animal Production "Improving Livelihood and Food Security of the people in Lower Mekong Basin through Climate Change Mitigation" in Cantho University, Vietnam. The authors would like to express sincere gratitude to the MEKARN II program, financed by Sida (Swedish International Development Agency) for supporting this research.

References

AOAC 1990 Official Method of Analysis. Association of Official Analytical Chemists. 15th edition (K Helrick editor). Arlington pp 1230

Chittakone Insixiengmai 2015 Effect of biochar and cultivation method on germination of sugarcane .Mini-project report, Nong Lam University

Glaser B, Lehmann J and Zech W 2002 ‘Ameliorating p. ysical and chemical properties of highly weathered soils in the tropics with charcoal – A review. Biology and Fertility of Soils 35, 219–230.

Gujja B, Loganandhan N, Goud V V, Agarwal M and Sraban D 2009 Improving Sugarcane Cultivation in India http://d2ouvy59p0dg6k.cloudfront.net/downloads/ssi_manual.pdf

Lehmann J 2007 A handful of carbon. Nature 447 143- 144 http://www.css.cornell.edu/faculty/lehmann/publ/Nature%20447,%20143-144,%202007%20Lehmann.pdf

Lehmann J and Joseph S 2015 Biochar for environmental management; science, technology and implementation (2^nd Edition.). Published by Earthscan UK and USA

Leng R A 2014 Interactions between microbial consortia in biofilms: a paradigm shift in rumen microbial ecology and enteric methane mitigation. Animal Production Science, 54, 519–543 Prspectives on Animal Biosciences http://dx.doi.org/10.1071/AN13381

Preston T R 2015 The role of biochar in farming systems producing food and energy from biomass. In: Geotherapy: Innovative methods of soil fertility restoration. In: Carbon sequestration, and reversing CO₂ increase (Editor Thomas J Goreau) CRC Press, Tayler and Francis Group, Boca Raton, Florida USA

Quirk R G, Zwieten Van L, Kimber S, Downie A, Morris S and Rust J 2012 Utilization of biochar in sugarcane and sugar-Industry management. Sugar Tech, October 2012, 14(4):321-326).

Zheng W, Sharma B K and Rajagopalan N 2010 Using Biochar as a Soil Amendment for Sustainable Agriculture. Illinois Sustainable Technology Center University of Illinois at Urbana-Champaigne. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.864.9944&rep=rep1&type=pdf

Received 14 April 2017; Accepted 30 October 2017; Published 2 November 2017

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