- Crop Management Technology
In terms of global production, sugar cane (Saccharum officinarum L.) is the world’s primary sugar crop. Current production stands at 1450 million tons of cane from 22 million hectares worldwide. Brazil and India are the world’s major sugar cane producing countries, accounting for nearly 60% of the global production.
In addition to its presence within the food industry, this crop is gaining enormous significance in the biofuel industry. Brazil, for example, uses 48% of its sugar cane production to produce ethanol, while the remainder is used for sugar production. In Asia, countries such as India, China, Thailand, Philippines and Pakistan have already drawn up ambitious plans to use sugar cane as a biofuel crop for ethanol production. Such a production will meet fuel mixture requirements such as E10 – where 10% of the fuel is ethanol and 90% is gasoline, among other fuel requirements (E5, E7, etc.).
Sugar cane is grown in more than a hundred countries under temperate, subtropical and tropical conditions. The sugar cane is basically a crop of tropical climates, with yields affected significantly by temperature, relative humidity and solar radiation. The optimum mean daily temperature range is 14 to 35°C. Likewise, relative humidity ranging between 55 – 85% at grand growth period favors stalk development. The optimal solar radiation requirement is 18 – 36 MJ/m2 (Total annual: 6350 MJ/m2). Stalk growth increases when daylight is in the range of 10 – 14 hours. Sugar cane can be grouped into three varieties: early, mid-late and late. Varieties resistant to several pests and diseases have also been developed in major sugar cane growing regions across the subtropical and tropical world.
Sugar cane requires a well-drained, well-aerated, porous soil with pH of 6.5. Compacted soils (> 1.6 to 1.7 g/cm3) affect root penetration, water and nutrient uptake. The crop is moderately sensitive to soil salinity. The planting pattern is dual or paired row and spacing adopted (1.4m + 0.4m) is 0.15m under drip irrigated conditions, while sowing depth is generally 10cm. The crop is grown by vegetative propagation and requires 40,000 two-bud1 or 30,000 three-bud setts2 per hectare in order to maintain a desired millable stalk population target of 130,000/ha.
The implementation of drip irrigation and fertigation in sugar cane has proved to be technically feasible and economically viable. In many diverse agro-ecological situations, drip irrigation registered higher yields (50 to 90 tons/ha), conservation of water (30 to 45%) and fertilizers (25 to 30%). Furthermore, drip irrigation accounts for the improvement in sucrose content compared to conventional furrow, overhead, dragline and center pivot sprinkler irrigation methods.
In Africa, under Swaziland conditions, subsurface drip irrigated sugar cane grown on 6715 ha for nine years (plant crop + 8 ratoon3 seasons), registered an average cane yield of 107 to 126 tons/ha and pol4 of 15.6 to 18.2 tons/ha. While the sucrose increase was 1.6 tons/ha/year, the accompanying results, in comparison to a dragline sprinkler system, were as follows: power conservation 4.6 kVA/ha/year, operations & maintenance conservation 140 USD/ha/year, water conservation 150mm/ha/year and an internal rate of return (IRR) of 29%.
For high yields, the seasonal crop water requirements for sugar cane crop were estimated at between 1100 to 1500 mm/ha under a range of climatic conditions and varying lengths of growing seasons (12 – 14 months), with a daily evapotranspiration rate of 4 to 7 mm/day. Using tensiometers in irrigation scheduling (25 – 60 centibars at different crop developmental stages) enables the efficient use of water, fertilizers and energy inputs.
Sugar cane is a heavy feeder of nutrients. Its root system is shallow and fibrous, therefore, fertigation is recommended for higher nutrient availability and use efficiency. The aim of the fertigation program is to bridge the gap between crop demand and supply. The nutrient requirements of drip irrigated sugar cane are relatively high: 250 to 300 kg/ha N, 80 to 100 kg/ha P2O5, 125 to 250 kg K2O per ha. The amounts of nutrients removed by sugar cane plants per ton of cane yield are as follows: 0.7 – 1.2 kg N, 0.4 – 0.8 kg P2O5, 1.8 – 2.5 kg K2O. Best management practices include earthing up, detrashing, propping, protection of crop from pests and diseases, need based weed management, crop logging, harvesting and post harvesting operations to minimize sugar losses.
1 A bud is a developing part of a plant that will grow into a flower, new leaf or stem.
2 A sett is a piece of cane stalk that contains roots and buds. When roots develop, they anchor the sett and provide food for the germination of the buds from which the cane stalk grows. In this way the stool is created and new roots develop.
3 A ratoon is the cane that grows from buds remaining in the stubble left in the ground after a crop has been harvested. One plant usually grows three to four ratoon crops.
4 A pol (polarisation) is a measure of the sucrose content of sugar. Sugar with 98 pol (or 98 degrees pol) contains about 98% sucrose.
Sugar Cane Best Practices
Conditions: Temperate, tropical and subtropical; long warm growing season, with high incidence of solar radiation and adequate moisture; a fairly dry, sunny and cool, but frost free season for ripening and harvesting; freedom from typhoons and hurricanes
Solar radiation: 18 – 36 MJ/m2 (Total annual: 6350 MJ/m2)
Rainfall: 1100 to 1500 mm/annum
Relative humidity: 55 to 80%
Optimum ambient temperature: 14 to 35°C
Soil suitability: Fertile, deep (up to 1.5 m), well drained and aerated soil (air-filled porosity: 10 – 12%), loamy to clayey in texture
Bulk density: 1.1 to 1.4 Mg/m3
Moderate topography (1 to 3º)
Optimum soil pH: 6.5 (range: 5 to 8.5)
Available water holding capacity: 150 mm/m depth of soil
Groundwater table: Below 1.5 to 2 m
Critical soil salinity level (ECe): Below 1.7 dS/m above which yield decreases
Soil to avoid: Waterlogged, alkaline and saline soils
- Clod free seedbed with good tilth to express its cane yield potential, SDI installation & optimal soil water air relations.
- Destroy the hard pan if any using either chisel plough or a subsoiler.
- Primary tillage by mould board plough or disc plough and secondary tillage by disc harrows, tyned harrows or rotavator to achieve proper tilth.
- Compost: 25 – 30 tons/ha
- Planting material
- Vegetative propagation
- Healthy two-bud or three-bud setts
Paired or dual row system
1.4 m + 0.4 m, 0.15 m
Optimum plant density – 130,000 millable canes/ha at harvest
Two bud setts – 40,000/ha or three bud setts – 30,000/ha
Seeding depth – 10 cm below the soil
Managing weeds is critical for successful sugarcane production since they compete for light, water, nutrients, etc. and reduce cane yields by 12 to 72% depending on the weed intensity.
Critical crop weed competition period is initial 90 – 120 days.
Integrated weed control program involving crop rotation, manual weeding, good seedbed preparation, maintenance of optimum plant population, mechanical inter-cultivation and herbicide chemical applications.
Recommended pre-mergence herbicides:
Lasso 48 EC 3.0 – 4.0 L/ha
Stomp 50 EC 1.5 L/ha
Atrazine 50 FW 3 – 4 L/ha
Diuron 80 WP 2.0 – 2.5 kg/ha
Ametryn 80 WP 2.5 – 3.0 kg/ha
Recommended post-emergence herbicides:
Ametryn 80 WP 2.5 – 3.0 kg/ha
Sencor 70 WP 2.5 – 3.0 kg/ha
MSMA 72 SC 4.0 L/ha
Drip version – Surface or subsurface drip irrigation (SDI) combined with fertigation. Fertigation is the application of plant nutrients through an irrigation system, also known as NutrigationTM.
Drip product – DripNet PC, Super typhoon, DLN 17009.
Dripline spacing – 1.8 m with one lateral per two crop rows.
Emitter spacing – 0.30 m to 0.50 m depending on soil texture.
Emitter flow rate – 1.0 LPH, 1.6 LPH and 2.0 LPH depending on soil texture.
Dripline installation depth in SDI – 0.15 m to 0.3 m
Crop water requirement & irrigation scheduling
Estimate crop water requirements as a product of daily reference crop evapotranspiration by Penman-Monteith method and crop coefficient for a given day according to the plant developmental stages.
Begin with 0.4 Kc of daily ETo in the initial period, raise it to 0.7 to 1.05 at tillering and canopy establishment phase, 1.2 at grand growth period and decrease it 1.15 to 0.95 to 0.7 at ripening and maturity period of sugarcane.
Peak crop water requirement: 6 – 7 mm/day in India & South Africa and 4 – 5 mm/day in Brazil.
Seasonal crop water requirement: 1100 to 1500mm under drip irrigation for range of environments.
Scheduling irrigations when tensiometers installed at 20cm soil depth register 15 – 25 centibars of soil moisture tension at tillering and grand growth period – 60 centibars at ripening period maximizes cane and sucrose yield.
Apply mineral fertilizers based on the targeted cane yield, leaf nutrient analysis, results of fertilizer experiment, leaf deficiency symptoms, nutrient uptake, soil nutrient analysis, and nutrient recycling.
Nutrient uptake per ton of cane yield:
0.7 – 1.2 kg N
0.4 – 0.8 kg P2O5
1.8 – 2.5 kg K2O
Optimum leaf nutrient levels are:
1.9 – 2.% N
0.2 – 0.24% P
1.1 – 1.3% K
0.2 – 0.3% Mg
0.8 – 1.0% Ca
0.25 – 0.30% S
9 – 30 ppm B
8 – 10 ppm Cu
100 – 250 ppm Mn
200 – 500 ppm Fe
25 – 50 ppm Zn
Recommended nutrient dose per hectare (under range of environments):
250 – 300kg N + 80 to 100kg P2O5+ 125 to 250kg K2O
For fertigation use only water soluble fertilizers such as:
urea (46% N)
potassium nitrate (13% N & 46% K2O)
monoammonium phosphate (12% N & 61% P2O5)
ammonium nitrate (34% N)
Earthing-up operation, also known as ‘hilling-up’, refers to placing of the soil around the plants and is carried out in two or three stages during sugarcane crop growing period.
Earthing-up checks late tillering, provides sufficient soil volume for root proliferation, controls weeds, promotes better soil aeration and provides a sound anchorage or support to the crop and thus prevents lodging.
The first earthing-up, also known as ‘partial earthing-up’, is done 45 days after planting. The second earthing-up and/ or third one is known as ‘full earthing-up’ and is done 120 & 180 days after planting, respectively.
Detrashing refers to the removal of unwanted bottom unproductive dry and green leaves at regular intervals. The reason for detrashing is to make more photosynthates available for stalk growth, enable CO2 enrichment in the crop canopy, reduce pests incidence & bud sprouting; and facilitate easy harvesting of cane.
Propping refers to the tying of leaves together using the bottom and middle level green leaves. Trash is twisted to form a sort of rope and cane stalks are tied together, without removing any trash from the cane. Propping is done to check lodging and damage to cane due to high wind velocities. Propping can be done for each row or for two rows that are brought together and tied.
Pests and diseases
Important pests include early shoot borer, inter-node borer, root borer, root grub, thrips, woolly aphids, scale insects, termites, wire worm, white flies, black bug, etc.
Important diseases include red rot, whip smut, pineapple disease, wilt, ratoon stunting disease, grassy shoot disease, yellow leaf spot, eye spot, ring spot, etc.
Detect outbreaks and identify problem areas by routine patrols. Monitor economic threshold levels and take up appropriate plant protection measures.
- Harvesting of sugarcane at peak maturity by adopting right technique is necessary to realize maximum weight of the millable canes (thus sugar) with least possible field losses under the given growing environment.
- Avoiding cutting of either over-matured or under-matured cane.
- Use standard criteria such as crop age, visual symptoms (drying of leaves and metallic sound of cane), quality parameters (juice Brix, pol or sucrose percentage and purity), etc. for determining cane ripening and maturity.
- Cut the cane to ground level so that the bottom sugar rich internodes are harvested which add to yield and sugar.
- Detop the cane and clean it properly before transporting it the sugar mill.
- Avoid delay in the field after harvest and quickly dispose the harvested cane to sugar mill or bio-refinery.
Under drip irrigation and fertigation a good commercial cane yield should be 140 – 160 tons/ha depending on agroclimatic conditions, length of growing season and variety.
Water utilization efficiency varies between 15 – 20 kg/m3.
How much a drip irrigation system costs per hectare of sugarcane?
This is very variable and depends on the following three factors:
– Conveyance of water from source to the field: normally this is the most expensive component of the irrigation system. It depends on the distance and elevation the water has to be conveyed by the pipelines.
– Peak crop water demand: Amount of water needed to apply to meet the peak crop evapotranspiration requirements during the crop peak demand. This is a function of prevailing climate conditions, crop canopy cover and efficiency of the irrigation system.
– Other considerations: The land topography of the design area – whether flat or undulated and the soil texture which determines the emitter spacing. For example, sugarcane on sandy soils require closer emitter spacing while clayey soil require wider emitter spacing that will have a significant impact on the system cost per unit area.
Why choose drip and not others irrigation methods “apparently” less expensive?
Since the drip technology was invented by Netafim in 1965, it proved itself to be technically feasible and economically viable under a large range of environments and crops, to include sugarcane. Drip was found to increase cane yields and number of ratoons as well as to improve the sucrose. Drip technology also allows significant saving in water, fertilizers, labor and energy required for pumping water. In the long run, economic calculations show that drip is the most suitable system for modern sugarcane agriculture with higher economic returns.
What should I do to guarantee the success of a drip sugarcane project?
The success of the sugarcane project depends on few crucial factors: Good agriculture practices like proper soil preparation, selecting the most suitable varieties for irrigation and fertilization, planting time, quality planting material, quality drip system components and irrigation design & timely harvesting.
For each project, Netafim provides the most customized solution package depending upon the local farm conditions, climate and management level of the customer that obviously differs from one project to the other.
As a sugarcane grower, should I use subsurface or surface drip system?
Subsurface drip irrigation has shown to have many agro-technical advantages for sugarcane growers, besides the regular drip features. There is no need to recollect the dripline before every harvest cycle, the driplines are protected from agro-machinery damage, it permits using a thin wall dripline that significantly effect the cost and it applies the water and the fertilizers directly to the sugarcane root zone. Finally, the grower can apply all the crop agro-machinery activities without interfering with the day to day irrigation system protocols.
What is the life of the drip system for sugarcane and after how many years I have to renew it?
The accumulated field experience revealed that sugarcane raised under subsurface drip irrigation system can continue up to eight and/or more ratoons before field is renewed for a new crop cycle.
During the renewal of the field for new plant crop all the hydraulics such as pipes, pump, filters, etc., remain intact on the field for further use and only the dripline must be replaced. This fact represents around 50% of the total system cost per unit area. /td>