1

WIRELESS AUTOMATIC IRRIGATION TO ENHANCE WATER

MANAGEMENT IN SRI PADDY FIELD1

Budi I. Setiawan2, Satyanto K. Saptomo

3, Hanhan A. Sofiyuddin

4, Gardjito

5

ABSTRACT

System of Rice Intensification (SRI) has received a wide attention as a technology package to

improve land and water productivities of paddy fields. Unlike conventional paddy field where

its soil surface mostly flooded with water, SRI paddy field is irrigated intermittently to

condition the soil surface close to, or saturated with water. In SRI Paddy Field, younger seeds

(8-12 days) are planted in a wider interval (25 cm x 25 cm, or more) which gives more spaces

for tillers and roots to develop more. As it has been proven elsewhere, SRI practice could

produce more rice per hectare, or increases land as well as water productivities. With organic

applications, SRI practice could improve soil conditions, and helps farmers to reduce the

utilization of chemical fertilizers and pesticides. SRI paddy becomes healthier with deeper

rooting and in some instances makes it tougher to bad weather like storm and pest outbreaks.

However, there are still remaining problems. SRI practice needs more labors especially during

planting and weeding, and tedious jobs to manage water levels by means of intermittent

irrigation and/or drainage. Some appropriate technologies are needed to handle these

problems. On water management aspect, an effort has been initiated by means of application

of automatic irrigation supported by a Wireless Station Network (WSN). In this technique, a

water level sensor is placed in the middle of SRI Paddy Field. Its output is transmitted to a

remote control room by means of radio wave, and then analyzed to get an output as a

command to regulate water valve back in the field. The technology being described further in

this paper is a promising one. However, it requires some adjustments on the existing irrigation

network if it is applied to the conventional paddy field.

Keywords: System of Rice Intensification, Selaras Principle, Water Management, Automatic

Irrigation, Wireless Station Network.

1 Presented in Regional Symposium on Engineering & Technology:” Opportunities and Challenges for Regional

Cooperations in Green Engineering and Technology”. Kuching, Serawak, Malaysia, 21-23 November 2011. 2

Department of Civil and Environmental Engineering, Bogor Agricultural University, Bogor, Indonesia.

Http://budindra.staff.ipb.ac.id; Email: budindra@ipb.ac.id. 3 Department of Civil and Environmental Engineering, Bogor Agricultural University, Bogor, Indonesia.

4 Irrigation Experimental Station, Center for Water Resource Research and Development, Ministry of Public

Work, The Republic of Indonesia. 5 Department of Civil and Environmental Engineering, Bogor Agricultural University, Bogor, Indonesia.

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INTRODUCTION

The rapid world population growth and industrial development have caused problems in food

and water supplies and other catastrophes especially in the developing countries (Yajima,

2002). Particularly in Asia with very high population and very low available arable land per

capita, rice has long been very important for dietary source and fulfilling human food needs

(Fresco, 2003). Furthermore, growing paddy has been the central livelihood strategy and is in

the blood of most of Asian farmers (Rijsberman, 2004). There are two major challenges

involving rice in Asia, i.e., (a) ensuring the ability of nations to meet their national and

household food security needs and (b) eradication of extreme poverty and hunger. Due to the

central position of rice to the lives of most Asians, any solution to global poverty and hunger

must include research that helps poor farmers earn a decent and reliable income by growing

rice affordable to poor consumers (Cantrell, 2004). The global rice production has so far been

able to meet population demands; however, a big question has already arisen on its

sustainability. Appropriate action has to be taken in the near future in order to solve the

problem (Nguyen and Ferrero, 2006).

A good opportunity to produce more rice with less water has been commenced when a new

method of rice cultivation called as System of Rice Intensification (SRI) was introduced in

1980 originally in Madagascar. Since then, SRI has been given a wide attention as a

technology package to improve land and water productivities of paddy fields. It is claimed

that SRI is a methodology that can contribute to food security by increasing rice yields to

about twice the present world average, virtually without the need of improved seeds or

chemical inputs as presented by Norman Uphoff, director of the Cornell International Institute

for Food, Agriculture and Development (CIIFAD), in his keynote on “The System of Rice

Intensification (SRI) and its Relevance for Food Security and Natural Resource Management

in Southeast Asia” (TROZ, 2002). It has been tested in China, India, Indonesia, the

Philippines, Sri Lanka and Bangladesh with positive results (Berkelaar, 2006). In the

beginning of its development some other scientists are, however, still skeptic and argue about

the success of the SRI method.

The practices recommended by SRI is somewhat counterintuitive, since it challenges

assumptions and practices that have been applied for hundreds or even thousands of years by

traditional rice farmers in Asia. No external inputs are necessary for a farmer to benefit from

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SRI. The methods should work with any seeds that are now being used. No purchase of new

seeds or the use of new high-yielding varieties (HYV) is required, although some of the

highest yields obtained using SRI have been from the HYVs of paddy. In SRI Paddy Field,

younger seeds (8-12 days) are planted in a wider interval (25 cm x 25 cm, or more) which

gives more spaces for the tillers and the roots to develop more.

The SRI practices for paddy cultivation conducted by farmers in Indonesia, particularly in

West Java, can be categorized as organic rice farming mostly sponsored by non-government

organizations (NGOs). So far SRI has only been tried in small scale where water requirement

and organic fertilizers were still manageable. With organic applications, SRI practice could

improve soil conditions, and helped farmers reducing chemical fertilizers and pesticides. SRI

paddies became healthier with deeper rooting in which in some cases became tougher to bad

weathers and to disease outbreaks. The sustainability of this organic farming system would

still be in question when applied in large scale due to its promising future in intensive rice

production.

The change from the traditional system into this SRI system might cause some changes in

socio-economic, technical, as well as environmental aspects of the rice production. It might

take some years for farmers to get confidence that this method could consistently raise

production so substantially. Therefore, some more in-depth researches still need to be

conducted concerning the socio-economic, technical, as well as environmental aspects. This

paper describes how we develop a wireless automatic irrigation system for maintaining

expected water level or soil moisture in SRI Paddy Field.

PRINCIPLE OF SRI DEVELOPMENT

In developing SRI Paddy Fields in Indonesia, we adopt the Selaras Principle (Setiawan,

2011) as a comprehensive guideline for sustainable biomass production. Such as illustrated in

Figure 1, Selaras Principle is a sort of optimization system, which has three objectives to

Maximize, to Minimize, and to Maintain expected outputs through a process of continuous

Improvements (3MI) subjected to a desired goal. In this case, the goal is to achieve a

sustainable SRI Paddy Field through a dynamic process by:

1) Maximizing the overall productivity and stakeholder prosperity;

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2) Minimizing people poverty, GHG emissions, contaminated effluents and

environmental degradation;

3) Maintaining biodiversity, natural amenity and local wisdom;

4) Improving input parameters, such as materials, technology, management, human

resource, infrastructure, regulation and law.

In this paper, we give emphasizes on improving water management to enhance land and water

productivity, and illustrations how proper water management can also minimize GHG

emissions.

Figure 1. Schematic Illustration of Selaras Principle to develop sustainable SRI Paddy Field in

Indonesia

LAND AND WATER PRODUCTIVITY

The overall productivity consists of three components, such as land productivity, which is

gross agricultural output per hectare of land (van Dongen and Lier, 1999). Water

productivity is gross agricultural output per volume of irrigation water (Molden, 2007). The

other component is water productivity that has a meaning of growing more food or gaining

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more benefits with less water6. Values of water productivity with respect to total water input

range from 0.2 to 1.2 kg grain m-3

water, with 0.4 as average value (Boumar et.al., 2005).

Herewith, maximizing land productivity and water productivity could have a meaning of

attaining them to, or passing through, specific targeted values. The third component is labor

productivity, a gross agricultural output per employee in agriculture (Dongen and Lier,

1999).

It is widely known that rice productivity or yield has a characteristic relation with

evapotranspiration (ET) described by the production function (Allen, et.al., 1990).

(1)

Where, Y and ET are Yield (ton/ha) and Evapotranspiration (mm), respectively; β is water-

yield sensitivity coefficient; and a and m are subscripts for actual and maximum values.

Figure 2. An Example of Yield function of rice dependence on Evapotranspiration for three

different water management (Data analyzed from William, et.al., 2007)

Figure 2 shows one pattern for the performance of Equation 1 analyzed from William, et.al,

(2007) who conducted their research in Andhra Pradesh State, India. The figure shows

different water managements produce different lines. Shallow Flooding with 5-10 cm water

level fluctuates above and below soil surface which gaines more land productivity and water

6 http://www.fao.org/nr/water/topics_productivity.html [19/09/2011]

6

productivity than those of Mid-season Drainage and Continuous Flooding (5-10 cm water

level above soil surface).

Figure 3. Gas emission as influenced by different water management (Data analyzed from

William, et.al., 2007)

Furthermore, gas emission of CH4 and NO2 are other side effects of different water

management such as clearly presented in Figure 3. Both gas emissions are not at any different

under Continuous Flooding and Mid-season Drainage but they are clearly different with those

under Shallow Flooding. In Shallow Flooding, CH4 emission decreases sharply even below

zero while NO2 increases significantly. This is simply because of denitrification and

decomposition processes (William et.al, 2007).

Effects of water level on greenhouse gas emission in paddy fields were also reported by Lee,

et.al., (2005) in Korea. The CH4 emission treated with rice straw was lower when the soil

moisture was under the maximum field capacity compared with those under 4 cm and 8 cm

water levels above the soil surface; while the NO2 emission was in the contrary. In term of

Global Water Potential (GWP), it was lower (=5,222 kg CO2 kg/ha) under the field capacity

compared to those under 4 cm (=6,431 kg CO2 kg/ha) and 8 cm (=6,939 kg CO2 kg/ha) water

level above the soil surface.

INTERMITTENT IRRIGATION IN CONVENTIONAL PADDY FIELDS

Rainfall is an example of natural intermittent watering but it is of course uncontrollable.

Intermittent irrigation is a human act in trying to give water to a farmland subjected to given

targets that varies with time. Intermittent-flow irrigation is defined as a system in which

each irrigator gets water only intermittently either by pre-established rotation of the basic

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flow or on demand according to the prior demands by individuals or group of individuals, of

the quantities and at the times that appear to them most desirable, or finally, in the most

modern pressurized systems, in total free service7.

Intermittent irrigation in paddy fields has been applied elsewhere. Among others, Dong

(1999) reported Intermittent Submerged Irrigation adopted in South China with shallow

depth of water on the soil surface between 20-40 mm in an averaged time interval of 7 over 8

days growth stages. In the late growth of tillering, water level was below the surface on the

condition of 0.6-0.8 under saturated water content. Furthermore, he reported that with

intermittent flooding, roots could extend downward 30~50 cm, the number of white roots was

nearly three times as much as that in conventional practice; vitality of root system was

promoted; and space for roots to assimilate nutrient and moisture was extended. However,

under this alternative wetting and dry condition, population of barnyard grass increased

evidently while the other types of grasses were similar to that under flooded condition.

Massey (2009) gave intermittent irrigation in paddy fields in Mississippi Delta with the water

level was gradually increased to reach 9 cm above soil surface in one period of flooding and

then let it decreased for the period of drying, and repeated this cycle in the interval of 7 to 10

days until 90 days, end of the season. Advantages of applying this intermittent irrigation were

increasing rainfall capture, reducing non-point sources of runoff, reducing water and energy

use, and reducing CH4 emission.

Hadi et.al., (2010) reported that Intermittent Drainage could reduce GWP in the range of

14.7% to 68.5% compared to the continuously flooding for three different varieties of rice and

two soil types in South Kalimantan, Indonesia. In the intermittent drainage, soil surface was

initially flooded but was then allowed to drain over 7-day interval and then re-flooded to the

previous level.

It is clear that intermittent irrigation or drainage could increase productivity while at the same

time could reduce GWP significantly. Among other on-farm water management systems, it

turns out that intermittent irrigation or drainage produced more advantages not only

increasing productivity but also decreasing GWP. However, the intermittent irrigation or

7 ICID Multilingual Technical Dictionary on Irrigation and Drainage.

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drainage is not easy to apply by common farmers because it needs intensive day-by-day

operation that might increase labor hours.

INTERMITTENT IRRIGATION IN SRI PADDY FIELDS

System of Rice Intensification (SRI) has received a wide attention as a technology package to

improve land and water productivities of paddy fields. The current progress on SRI

development in the world has been published in the Special Issue of Paddy and Water

Environment (Uphoff and Kassam, 2011). Hasan and Sato (2007), and Sato et.al (2011) gave

detail explanation of the different between SRI method and the conventional method applied

in Indonesia (Appendix 1). Among the differences in the aspect of water management, SRI

applied intermittent irrigation in the vegetative stage and shallow depth of water (2-5 cm) in

the reproductive stage. They reported that there were significant increases in yields of SRI in

the range of 29.5% to 92.9%. Lin et.al (2011) also obtained better yields after applying

intermittent irrigation with the combination of organic fertilizers application.

Hasan and Sato (2007) applied intermittent irrigation in SRI Paddy Fields. They could save

irrigation water about 40% and increased yields ranged from 29.5% (5.58 ton/ha) up to 92.9%

(7.10 ton/ha) with an average of 78% (7.61 ton/ha). Intermittent irrigation was given at the

vegetative stage with only shallow standing water (± 2 cm) during the wet periods. At

reproductive stage, however, the field was given a continuous irrigation with standing water

of 2-5 cm.

In Indonesia, SRI Paddy Field is irrigated intermittently to condition the soil surface close to,

or saturated with water. Continuous flooding paddy fields with water at the averaged rate of

1.1 l/s per hectare (Direktorat Bina Teknik, 1997) as the standard irrigation has been proven

not conducive for plant growth and low efficiency of water use. Whilst, maintaining soil

moisture 80% under saturated condition has stimulated better growth above as well as below

ground biomass, soil microbe’s activity and water use efficiency (Balai Irigasi, 2009). Water

efficiency has increased 45% without jeopardizing production, moreover in some areas

enhanced productivity, when intermittent irrigation introduced into SRI paddy fields (Balai

Irigasi, 2009). However, SRI practice needs more labors especially during planting and

weeding, and tedious jobs to manage water levels by means of intermittent irrigation and/or

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drainage. Farmers have to go to the field more frequently for monitoring water level and

operating irrigation gates that always resulted in significant deviation of the targeted water

level.

WIRELESS AUTOMATIC IRRIGATION

Attempts to apply automatic irrigation and drainage in Indonesia have started in the early

2000, for examples by Setiawan et.al. (2001a), Setiawan et.al. (2001b), Setiawan et.al (2002)

and Saptomo et.al. (2004), which were trying to control water level subjected to certain

targets by operating irrigation and drainage pumps. Those techniques using cables to receive

and transmit data gained satisfied results. However, they had limited capability when dealing

with larger area of paddy fields. Technology improvement was needed to handle these

problems.

Figure 4. Automatic irrigation with Wireless Sensor Network

Currently, we are developing wireless automatic irrigation supported by a Wireless Station

Network (WSN). Figure 4 shows schematic illustration in which WSN consists of water

level and soil moisture sensors connected with cable to a receiving node that can transfer data

through a radio wave to a remote gateway. If necessary to enhance the signal, a repeating

node is laid in between the node and the gateway that has long distance of 100 m from the

field. Data received by the gateway is sent to a computer or Programmable Logic Processor

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(PLC) to analyze and determine a proper command transmitted back through the node in the

field that connects to a solenoid valve for irrigation water. The command could open or close

the water valve in a certain opening depending upon required water flow output from data

analyses and control processing.

Water level sensor is WL 400 from Global Water Instrument (GWI) which has measurement

range of 0-3’ and accuracy of ± 0.1 %, current output of 4 – 20 mA and power supply of 8-36

VDC. Flow meter is Hall Effect type from GWI with digital output having measurement

range of 0.2 - 30 ft/sec (0.06 - 9.14 m/sec), accuracy of ±1 %, and power supply of 6 - 24

VDC and minimum current output of 8 mA. Solenoid valve 2” is fabricated by Valvorx with

DC supply of 12 V (2 A) or 24 V (1 A). Node and Gateway are from National Instrument (NI)

having radio frequency of 2.4 GHz. The node has 4 analog inputs and 4 digital inputs/outputs,

and transmitting coverage up to 300 m. National Instrument also provides Lab View as the

Tools to develop a control program (Figure 5) with the objective to maintain water level at a

certain point below the soil surface.

Figure 5. Control program developed using Lab View from National Instrument

The SRI paddy field was located in the experimental sites of Irrigation Research Station

belong to the Ministry of Public Work, Bekasi Regency, West-Java, with an area of 0.01 ha.

Irrigation water flowed from a reservoir through 2 inch water pipe controlled by the water

valve. The paddy field had an overflow 5 cm above the soil surface and under-drain pipe of

50 cm below the soil surface. WL sensor as a piezometer was located in the center of the

paddy field at the depth of 20 cm below the soil surface to measure water level intensively in

the interval of 5 minutes. In this preliminary experiment, the control strategy was simply an

ON/OFF type with the outputted command was whether to open or close the irrigation water

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valve. The valve opened when the actual water level reached the lowest water level at 3 cm

corresponding to the depth of 17 cm from the soil surface, and closed after reaching the

highest water level at 5 cm above the soil surface.

The first trial to test the performance of the control system was conducted in between October

to December 2010 where rain fall almost every day in the afternoon or evening and because

of that the water level in the paddy field was frequently above the soil surface. Consequently,

drainage was playing important role on maintaining water level. Irrigation water entered to

the field in several occasions between 10:00 to 15:00 when the water level reached the lowest

level due to the combination of internal drainage and evapotranspiration.

Figure 6. Some results of controlled water levels with the lowest and the highest set points

were 3 cm and 25 cm, respectively.

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As shown in Figure 6A, initially at day time water level is about 2.5 cm above the soil

surface, then decreased gradually mainly due to the internal drainage and evapotranspiration

until reaching the lower set point at 17 cm below the soil surface. Later on, irrigation water

flowes in automatically raising the water level fast, reaching the upper set point at 5 cm above

the soil surface then the water level decreases gradually. In general, water level data is in line

with its 10-moving average. However, some data is scattered far away from the line that

might be caused by noise or affected by atmospheric pressure.

Subsequently as shown in Figure 6B, at night time, water level is much or less stable above

the soil surface, which is mainly caused by the internal drainage since at night time

evapotranspiration is negligibly small. But again at day time (Figure 6C), water level

decreases immediately reaching the lowest set point clearly due to evapotraspiration effects

such as seen in the figure. Evapotranspiration data is obtained hourly from the weather station

in the location. The water level drops below the lower set point is on purpose to see the effect

of evapotraspiration during the day time. At this moment, the controller is shut off. It is clear

that evapotranspiration is the main factor in decreasing the water level during the day time.

Immediately after the controller resumes to operate (Figure 6D), water level comes closer to

and could attain to the upper set point, but then exceeds it due to heavy rainfall. Later on after

the rainfall ceases the water level immediately decreases to the upper set point due to the

existence of overflow at 5 cm above the soil surface.

CONCLUDING REMARKS

In general, the wireless automatic irrigation control has worked properly on maintaining water

levels within the desired range. Irrigation water valve is responsive in receiving command

from the remote control room. Noise appears around ± 0.5 cm but not disturbing the whole

system, and later on it could decrease when the time interval increases. The technology is

promising but requires adjustments on the existing irrigation network if applied to the

conventional paddy fields. Further testing is still undergoing in a larger area of SRI Paddy

Fields in PT. Sang Hyang Sri, West Java, Indonesia. The progress can be monitored via

http://emsa-sri.org/emsa-sri-sites.

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APPENDIX

Appendix 1. Standard Paddy Cultivation Practices for SRI and Conventional Method (Hasan

and Sato, 2007)