BRIDGING THE RICE YIELD GAP IN INDONESIA - Abdul Karim Makarim^*

^* Central Research Institute for Food Crops, Jl. Merdeka 147, Bogor, Indonesia

There is a growing demand for rice with increase in population. As rice is still the major staple food in Indonesia, the task of increasing rice production continues to engage the attention of national planners. There are five identified avenues to increase rice production, namely: a) by increasing the area under rice production through either increasing the cropping intensity or expansion into new lands; b) by increasing rice productivity; c) by stabilizing rice yields; d) by narrowing the rice yield gap; and e) by reducing yield losses during harvest and post-harvest (CRIFC 1991). In this context, increasing cropping intensity is related to the improvement/building irrigation systems to enable planting of two or three rice crops per year. Productivity is related to finding new high yielding rice varieties that potentially increase the yield per ha; stabilizing rice yields by better pest management to prevent or to control pest attacks and disease incidence; and post-harvest activities related to development of harvest and post-harvest technologies. The efficacy and efficiency of those methods for increasing rice production differ from one region to another, which are dependent on natural and socio-economic conditions. The objectives of this paper are to present the variation of rice yields in Indonesia, identify the causes of yield gaps, and delineate unmanageable and manageable factors to bridge the yield gaps.

Large variations in rice yield levels in Indonesia are due to many factors. Those factors have different scales of magnitude within regions, provinces, and districts up to farmers’ field level. Those factors are also classified as manageable and unmanageable. Yield gaps, therefore, should be divided into different scales and management. Yield gaps at different levels in various areas are indicated by the lowest and the highest yields of rice in such areas as compared to their average.

The priorities of reducing yield gaps (bridging) are possibly either to increase the lowest yield to the average or to increase yields that give the highest impact to rice production of those areas. The data on rice yields at provincial level are presented in Table 1, while described yield gaps are presented in Figure 1.

Table 1. Harvest Areas, Production and Yield of Lowland Rice in each Province in Indonesia in 1996

Province	Harvest Area (ha)	Production (tonnes)	Actual Yield (t/ha)	Range of Actual Yield (t/ha)
1. D.I. Aceh	339785	1400425	4.12	3.75-4.81
2. North Sumatra	716182	2966681	4.14	3.57-4.66
3. West Sumatra	411716	1929622	4.69	3.89-5.29
4. Riau	116766	389776	3.34	3.12-3.47
5. Jambi	152383	530186	3.48	3.14-3.97
6. South Sumatra	395253	1456587	3.69	3.26-4.22
7. Bengkulu	91259	337835	3.70	3.51-3.84
8. Lumping	370942	1620487	4.37	4.16-4.65
Sumatra	2594286	10631599	4.10	3.12-5.29
9. DKI Jakarta	3576	17347	4.85
10. West Java	1957743	10342690	5.28	4.34-5.59
11. Central Java	1534936	8170309	5.32	4.49-6.09
12. Yogyakarta	100125	562025	5.61	4.74-5.85
13. East Java	1529309	8377019	5.48	4.48-5.85
Java	5125689	27469390	5.36	4.34-6.09
14. Bali	155964	836047	5.36	5.22-5.65
15. Western-S.E. Nusa	268327	1232870	4.59	3.84-4.80
16. Eastern-S.E. Nusa	101657	323246	3.18	2.50-3.39
17. East Timor	17418	48835	2.80
Bali & S.E. Nusa	543366	2440998	4.49	2.50-5.65
18. West Kalimantan	242030	674537	2.79	2.29-2.94
19. Central Kalimantan	102530	269530	2.63	2.01-2.82
20. South Kalimantan	355378	1103402	3.10	2.69-3.95
21. East Kalimantan	82436	248596	3.02	2.89-3.10
Kalimantan	782374	2296065	2.93	2.01-3.95
22. North Sulawesi	103130	446693	4.33	3.88-4.52
23. Central Sulawesi	163500	561383	3.43	3.10-3.57
24. South Sulawesi	841066	4008277	4.77	3.46-5.60
25. S.E. Sulawesi	77887	276556	3.55	3.10-3.70
Sulawesi	1185583	5292909	4.46	3.10-5.60
26. Maluku	6626	19619	2.96	2.94-3.01
27. Irian Jaya	13469	37675	2.80
Maluku & Irian Jaya	20095	57294	2.85	2.94-3.01
INDONESIA	10251393	48188255	4.70	2.01-6.09

Source: BPS (1998): Produksi Padi di Indonesia 1997 Ramalah III. BPS.

Figure 1. Rice Yield Gap in Indonesia

2. MAJOR RICE YIELD GAPS

Indonesia is a large tropical country that consists of thousands of islands located in two Oceans (Indian and Pacific), lying between two continents (Asia and Oceania). Therefore, the spatial weather and soils vary widely. Those variables could be separated into: a) unmanageable variables (solar radiation, minimum and maximum air temperatures, soil texture etc.), and b) manageable variables (water flows and distribution, poor drainage, soil fertility, chemical toxicities etc.). Besides these natural conditions, other factors such as farmers’ traditional methods and knowledge, availability of technology, and socio-economic factors also determine and influence rice yield levels.

In 1996 there were 10,251,393 ha of rice harvested area in Indonesia with a production of 48,188,255 tonnes of grain, and an average yield of 4.70 t/ha. However, the yields usually range from 2.01 to 6.09 t/ha. Yield potential ranges from 5.788 to 7.087 t/ha which indicates that there is still a wide gap from the actual yield level in farmers’ fields.

Based on the average yield levels of rice there are three groups of regions (demarcated by major rice yield gaps) in Indonesia namely: Group I - Java and Bali (5.36 t/ha), Group II - Sulawesi, Sumatra and Nusa Tenggara (4.1-4.6 t/ha), and Group III - Kalimantan, Maluku and Irian Jaya (<3.0 t/ha). The major constraints and limitations of rice yields in those areas are different so that the strategies to reduce yield gaps among regions or to increase the average yield levels in those regions should be specific and peculiar to each region or group.

2.1 Yield Gaps at Regional Level

In group I (Java and Bali), the rice yield at provincial level ranges from 5.28 to 5.61 t/ha (average of 5.36 t/ha), except Jakarta with 4.85 t/ha (Table 2). In general, in this region almost no technical problems are confronted to limit relatively high yield level. The constraints are mostly in social and economical aspects such as low price of product, i.e., less profit compared to the profits obtained if producing other commodities. Increasing the efficiency of production is more beneficial than increasing inputs to obtain higher yield, which increase farmers’ profits and cause less chemical pollution. Improving grain quality of rice is more beneficial in order to get higher prices and profit.

Table 2. Rice Yield Gap at Provincial Level

Region	Actual Yield (ton/ha)		Yield Gap A	Potential Yield (ton/ha)	Yield Gap B
	Average	Range
GROUP I
1. DKI Jakarta	4,85				-
2. West Java	5,28	4,34-5,59	1,25	6,16-7,09	1,33
3. Central Java	5,32	4,49-6,09	1,60	5,85-6,78	0,99
4. Yogyakarta	5,61	4,74-5,85	1,11	5,85-6,78	0,70
5. East Java	5,48	4,48-5,85	1,37	5,79-6,74	0,78
Java	5,36	4,34-6,09	1,75	5,79-7,09	1,08
6. Bali	5,36	5,22-5,65	0,43	6,00-6,92	1,10
Java & Bali	5,32	4,34-6,09	1,75	5,79-7,09	1,12
GROUP II
7. DI Aceh	4,12	3,75-4,81	1,06	6,19-6,40	2,17
8. North Sumatra	4,14	3,57-4,66	1,09
9. West Sumatra	4,69	3,89-5,29	1,40	6,64-6,97	2,12
10. Riau	3,34	3,12-3,47	0,35
11. Jambi	3,48	3,14-3,97	0,83
12. South Sumatra	3,69	3,26-4,22	0,96	6,12-6,39	2,57
13. Bengkulu	3,70	3,51-3,84	0,33
14. Lampung	4,37	4,16-4,65	0,49
Sumatra	4,10	3,12-5,29	2,17	6,12-6,97	2,45
15. North Sulawesi	4,33	3,88-4,52	0,64
16. Central Sulawesi	3,43	3,10-3,57	0,47	6,37-6,49	3,00
17. South Sulawesi	4,77	3,46-5,60	3,14	5,98-6,24	1,34
18. S.E Sulawesi	3,55	3,10-3,70	0,60
Sulawesi	4,46	3,10-5,60	2,50	5,98-6,49	1,77
19. Western-S.E. Nusa	4,59	3,84-4,80	0,96
20. Eastern-S.E. Nusa	3,18	2,50-3,39	0,89	6,31-6,39	3,17
S.E. Nusa
Sumatra, Sulawesi & S.E Nusa	3,96	2,50-5,60	3,10
21. East Timor	2,80
GROUP III
22. West Kalimantan	2,79	2,29-2,94	0,65
23. Central Kalimantan	2,63	2,01-2,82	0,81
24. South Kalimantan	3,10	2,69-3,95	1,26
25. East Kalimantan	3,02	2,89-3,10	0,21
Kalimantan	2,93	2,01-3,95	1,94
26. Maluku	2,96	2,94-3,01	0,07
27. Irian Jaya	2,80
Kalimantan, Maluku & Irian Jaya	2,88	2,01-3,95	1,94
INDONESIA	4,70	2,01-6,09	4,08	5,79-7,09	1,74

In group II (Sulawesi, Sumatra and Nusa Tenggara) rice yields vary from 3.18 to 4.77 t/ha with an average of 4.35 t/ha. In Sumatra generally, the problems of low rice yield are edaphic factors such as poor drainage, iron toxicity and high acidity either due to high sulphate or organic acids. In Sulawesi and Nusa Tenggara, the limiting factors in obtaining higher rice yields are dry climate, water shortage and drought. In both sites the problems and constraints could be overcome with large scale amelioration or improvement of supplementary irrigation systems. In Sumatra, improvements of drainage systems, application of rock phosphates and/or dolomitic limestone are required to increase rice yield or to shorten rice yield gaps. In Sulawesi and Nusa Tenggara improvement of irrigation systems or in some instances, pumping ground water may be important to increase rice yield. In those areas soil fertility is relatively good. In this group it is important to adopt the specific, adaptive rice varieties such as a drought tolerant varieties, acid tolerant varieties and high iron tolerant rice varieties. Such varieties are available in Indonesia for dissemination to rice farmers.

In group III (Kalimantan, Maluku and Irian Jaya), rice yields range from 2.63 to 3.10 t/ha with an average of 2.91 t/ha. In this group, the problems are complex, edaphic and socio-economic factors such as iron toxicity, soil acidity, poor drainage, lack of human resources, technology and low quantity and quality of production inputs are major constraints. However, the priorities to increase rice production in these areas are through farmers’ education/training and guidance to adopt new and simple technologies such as adaptable varieties, good seed, simple tools and machinery.

2.2 Rice Yield Gaps at Provincial Level

Yield gaps at provincial level are divided into yield gap among the average yields in the district levels and gaps of the actual yield level to the potential yield level. In group I in West Java, the average rice yield is 5.28 t/ha and ranges from 4.34 to 5.59 t/ha. Therefore, the actual rice yield gap among districts in West Java is 1.25 t/ha. On the other hand, rice potential yields range from 6.14 to 7.09 t/ha with an average of 6.62 t/ha. The gap between the average actual yield and the potential yield in west Java is 1.34 t/ha. In Central Java, the average rice yield is 5.32 t/ha and ranges from 4.49 to 6.09 t/ha. Therefore, the actual rice yield gap among districts in Central Java is 1.60 t/ha. On the other hand, rice potential yields range from 5.85 to 6.78 t/ha with an average of 6.32 t/ha. The gap between the average rice yield and the potential yield in Central Java is 0.99 t/ha. In East Java, the average rice yield is 5.48 t/ha and ranges from 4.48 to 5.85 t/ha. Therefore, the actual rice yield gap among districts is 1.37 t/ha. On the other hand, rice potential yields range from 5.79 to 6.74 t/ha with an average of 6.27 t/ha. The gap between the average rice yield and the potential yield in East Java is 0.79 t/ha. In Bali the average rice yield is 5.36 t/ha and ranges from 5.22 to 5.65 t/ha. Therefore, the actual rice yield gap among districts is very small (0.43 t/ha). In Bali, the irrigation network called Subak system is very effective in water distribution to farmers’ fields. Water management is controlled by groups of farmers. Therefore, the gaps of rice yields among farmers’ rice fields are very small. On the other hand, rice potential yields range from 6.00 to 6.92 t/ha with an average of 6.46 t/ha. The gap between the average rice yield and the potential yield in Bali is 1.10 t/ha.

In group II in West Sumatra, the average rice yield is 4.69 t/ha and ranges from 3.89 to 5.29 t/ha. Therefore, the actual rice yield gap among districts in West Sumatra is 1.40 t/ha. On the other hand, rice potential yields range from 6.64 to 6.97 t/ha with an average of 6.81 t/ha. The gap between the average rice yield and the potential yield in West Sumatra is 2.12 t/ha, much higher compared to the group I (Java and Bali). In South Sulawesi, the average rice yield is 4.77 t/ha and ranges from 3.46 to 5.60 t/ha. Therefore, the actual rice yield gap among districts in South Sulawesi is 2.14 t/ha. High variation in gaps of rice yields in the farmers’ fields is mainly due to the availability of irrigation water. On the other hand, rice potential yields range from 5.98 to 6.24 t/ha with an average of 6.11 t/ha. The gap between the average rice yield and the potential yield in South Sulawesi is 1.34 t/ha. In East Nusa Tenggara, the average rice yield is 3.18 t/ha and ranges from 2.50 to 3.39 t/ha. Therefore, the actual rice yield gap among districts in East Nusa Tenggara is 0.89 t/ha. Low rice yields in the farmers’ fields are mainly due to the lack of irrigation water. On the other hand, rice potential yields range from 6.31 to 6.39 t/ha with the average of 6.35 t/ha. The gap between the average rice yield and the potential yield in East Nusa Tenggara is 3.17 t/ha. The potential yield in this area is high due to high solar radiation. The maximum and minimum air temperatures are not a constraint to rice crop production. In general, water is not a limiting factor and no soil fertility constraints affect the rice crop.

In group III, the average rice yields in Kalimantan, Maluku and Irian Jaya are 2.93, 2.96 and 2.80 t/ha, respectively, lower than that of group II (4.35 t/ha). In Kalimantan, the descending order of yield gaps are South Kalimantan (1.26 t/ha), Central Kalimantan (0.81 t/ha), West Kalimantan (0.65 t/ha), and East Kalimantan (0.21 t/ha). Rice yield gaps among farmers’ fields in Maluku and Irian Jaya are not significant, because the yield levels are mostly low. Therefore, the important thrust is to increase rice yield, at least to come close to the average yield of group II.

3. STRATEGY FOR BRIDGING RICE YIELD GAPS

In brief, strategies for bridging rice yield gaps in Indonesia are as follows:

a) to improve the infrastructure and methodology (technical improvement, socio-economic improvements, better policy environment) such as construction and improvement of irrigation systems including groundwater exploitation, improved drainage systems, and soil amelioration;

b) to set priorities on increasing rice yields of the districts having lower average yield compared to the average yield level of their province;

c) site specific improvements: prescription farming, using adaptable rice varieties etc.

Prioritized districts in each province to increase rice yield or to reduce yield gaps are using the aforementioned method. In group I, there is no special district to prioritize to increase rice yields. In this area, bridging rice yield gaps should be done in line with increasing the efficiency of production inputs such as adopting prescription farming, and using high-value rice varieties (of high grain quality with high price). Using the prescription farming procedure, in which the needs for fertilizers on rice are calculated based on soil tests, targeted yield levels and climate, the efficiency of fertilizer usage could be reduced or even the rice yield could be increased. Examples of prescription farming results are presented in Table 3.

Table 3. Examples of Results of Prescription Farming in West Java using PADI300.CSM Simulation Model (Makarim 1999)

Location Number	Farmer Number	District	Regency	Village	Farmer				Optimum Dosage				Predicted Yield kg/ha	Note
					Urea kg/ha	SP-36 kg/ha	KCl kg/ha	ZA kg/ha	Urea kg/ha	SP-36 kg/ha	KCl kg/ha	ZA kg/ha
1	1	Garut	Selawi	Cigawir	240	190	125	0	175	35	79	0	6072	P, K Def. & Fe Tox.
2	2			Cinunuk	130	210	100	0	162	3	74	0	6195	Low K
	3				440	270	70	0	162	3	74	0	6195
	4				360	200	72	0	162	3	74	0	6195
3	5	Sumedang	Darmaraya	Cibogo	180	110	70	0	103	40	78	0	6530	P, K Def. & Fe Tox.
	6				180	110	90	0	103	40	78	0	6530
	7				120	120	60	0	103	40	78	0	6530
4	8		Sumedang Utara	Marga mukti	200	75	50	0	103	63	69	0	5659	P Def.
5	9	Cianjur	Cilaku	Sirnagalih	200	100	100	0	115	39	30	0	6552	P Def., Low K, potential, Fe Tox
6	10		Bojong Picung	Cibarengkok	380	150	38	0	175	0	59	0	6072	Good
	11				150	150	60	0	175	0	59	0	6072
	12				430	280	140	0	175	0	59	0	6072
	13				200	300	0	0	175	0	59	0	6072
7	14		Ciranjang	Mekar Galih	200	100	100	0	175	14	79	0	6072	K Def, Fe & Mn Tox.
8	15	Subang	Pagaden	Sumur Gintung	300	300	0	0	199	74	54	0	5279	P def
	16				250	100	50	0	199	74	54	0	5279
	17				200	100	0	0	199	74	54	0	5279
	18				300	150	0	0	199	74	54	0	5279
9	19		Binong	Nangerang	200	50	50	0	175	30	94	0	5648	Fe & Mn Tox.

In group II, the districts that are below average are Riau, Jambi, Bengkulu, South Sumatra, Central Sulawesi, Southeast Sulawesi and East Nusa Tenggara (NTT). Riau, Jambi, Bengkulu and South Sumatra are located in east Sumatra and have mostly acid, light texture and infertile soils. Therefore, besides the major improvements as mentioned before, rice fields in these sites also require K and probably micronutrients (Cu and Zn). In newly opened irrigated rice fields in Indragiri Hulu and Riau, the rice plants failed to produce good grain yield for almost six years due to iron toxicity and micronutrient deficiencies whereas in the surrounding areas rice crops produced normal narrow grain yield (Makarim et al. 1997). In Central and Southeast Sulawesi and East Nusa Tenggara, besides the major improvements as mentioned before, application of micronutrients (Cu and/or Zn) is required due to neutral to high pH of soils in this region.

In group III (Kalimantan, Maluku and Irian Jaya), since in most districts rice yields are still low, all districts try to increase rice yields through better guidance, improvement of farmers’ technical skill, good seeds and adaptable rice varieties.

The details of strategies are presented as the thrusts to increase rice yields and bridging rice yield gaps (Table 4). Based on sources of yield variation and constraining factors in each region, provinces or districts, appropriate solutions have been identified.

Table 4. Thrusts in Bridging Rice Yield Gaps in Indonesia

No.	Sources of Variation	Factors/Constraints	Solutions
1.	Yield potential (Java and Bali)	Weather condition (Solar radiation and air temperatures)	High yielding variety, time of planting
2.	Water Availability/irrigation (Nusa Tenggara and Sulawesi)	Drought with different levels	Improved irrigation, variety adaptable to drought and/or short duration
3.	Soil Properties	Acidity, Fe toxicity, Salinity (Sumatra, Kalimantan, Irian)	Water control (drainage), ameliorant (rock P dolomitic lime), tolerant varieties
4.	Shallow top soils, poor drainage, sandy texture (Kalimantan)	Soil Properties	Deep plowing, drainage, O.M.
5.	Soil fertility Pests and diseases	Nutrient deficiency Pest and disease problem	Prescription farming IPM, harvest and planting at the same time
6.	Availability of manpower and machinery (Maluku, Irian, Kalimantan, NTT)	Labour	Introduce tools and machinery for harvest, planting, and soil tillage
7.	Economic factors	Prices, costs Markets, transport, capital, credits	Stable price, profitable; systems of markets and transportation
8.	Social factors	Willingness to plant rice; Values (feel ashamed of failure or proud of success), guidance	Information system. Strengthen the function of farmers’ groups: Koperasi; Professional farmers’ groups (KTNA)
9.	Policy	Injustice and imbalanced supports	Credits, owners limitation, floor price, import control

4. CONCLUSIONS

Appropriate strategies in bridging the rice yield gaps should be relevant to:

Facilities:

· Irrigation systems
· Drainage systems
· Transportation
· Markets

· Prescription farming (fertilizer and organic matter)
· Water management (irrigation, drainage)
· Pests and disease control
· Seeds and variety improvement
· Tools and machinery

· Price of inputs (fertilizer, insecticides, etc)
· Price of outputs (rice, grain)
· Capital (credit)
· Labour costs

· Motivated farmers
· Guidance and information systems
· Set value (higher status of good farming practices)

· Better credit
· Price (floor pricing)
· Import controls

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