Fig. 01, showing lands used for rice cultivation, looks impressive. The rice yield cultivated in irrigated lands vs. rain-fed or upland fields may range from 4-6 tons - (ha-season)-1 vs. 1.5-2.5 tons - (ha-season)-1, respectively. Further, irrigated ricefields are used about 2-3 times each year, more than doubling the total rice production per year. In contrast, rainfed and upland farms used for rice cultivation is used only once each year, when there is enough rain to flood the land throughout the duration of rice cultivation.
Fig. 01 seems to indicate as if all the irrigable lands of 3.02Mha (see Fig. 02 for irrigable lands) have been irrigated and more (3.25Mha of irrigated lands were used for rice production, based on the latest 2014 data), and every irrigated land (1.68 Mha irrigated lands as reported by NIA) were used for rice production.
It is quite apparent that there is an unexplained discrepancy between the total irrigated lands used for rice production because a number of sources indicated just about over 50% of ricelands are irrigated, so far.
If the 50% irrigation is correct, does this mean another 2-3Mha of ricefields that can be irrigated? Some of these lands may come from the rainfed lowland used for rice cultivation during the rainy season but this cannot include the upland areas used for rice cultivation during the rainy season also, because the upland areas cannot be irrigated using conventional irrigation systems?
Total of 1.68 million hectares (Mha) of Irrigated Lands in the Philippines
The National Irrigation Admistration (NIA) estimated about 1.68Mha of total irrigated lands -- out of the total 3.02Mha irrigable lands from the 9.67Mha total of agricultural lands in the Philippines (Fig. 02).
The total farmlands available for rice cultivation cannot exceed 4.9Mha (review total land for rice production in Fig. 01, and ricefields cultivated for rice production based on 2014 data, to be presented in Fig. 03). The total arable lands (Figs. 02 and 03) used for cultivation of temporary crops (i.e., rice, corn, vegetables and others that takes less than a year from planting to harvest) is estimated at about 4.9Mha.
However, from Bureau of Agriculture Statistics (BASTAT) data, the combined total for lands used for rice and corn cultivation was 7.35Mha, well over the 4.9Mha total for arable lands (LAR, see Fig. 02 and 03).
If the NIA data is correct, the total irrigated lands used for rice production would even be lower than 1.7Mha (Fig. 02), since irrigation water is used also for high value crops and vegetables, animal husbandry and aquaculture. And, if it is correct that the irrigated area used for rice production is just about half (or even less) of what is indicated in Fig. 01, it is an ever better news:
First, the rice yield per season is even higher (and closer to yield potential of the rice varieties used today).
Second, if only 1.7Mha so far has been irrigated, then there are 1.4Mha of the total 3.1Mha irrigable land that can be irrigated. This will provide the potential for greater land productivity as more lands become irrigated in the future.
Sources of Irrigated Lands Data
Further literature search on the total irrigated lands in the Philippines; irrigated land usage; and analysis of the annual palay (harvested rice) production, actual yield of palay per season and annually, provided numbers for irrigated rice fields that are rather variant depending on the source of information.
The FAO data used in the graph by PhilRice is readily available online, and is quoted widely in many review and feature articles about rice production and policies relevant to rice resources, including importation for countries, like the Philippines.
The World Bank archive, placed irrigated areas in the Philippines at 9.1-9.2% in 2011-2012. Assuming, about 9.7 million hectares of agricultural land (BASTAT data), that would be less than 1 million hectares of irrigated land.
The National Statistics Office (NSO) data for 2002 more than doubles the number, but it is unclear whether the expanded meaning of the definition of irrigation (e.g., to include water carried by farmers from nearby streams, manual pumps, etc.) would really suffice to provide for rice cultivation.
The National Irrigation Administration (NIA), estimated about 1.7 million hectares of irrigated lands in 2013 (out of the 3.1 million irritable, the latter is less than a third of the 9.7 million agricultural lands). Figure 02 presents the irrigated rice fields (LI) vs the total area of irrigated lands (LTI-NIS) from 2000-2014.
Analysis of Bureau of Agriculture Statistics
It is a striking coincidence that the total irrigated ricelands area (blue filled diamond,, Fig. 2) is almost about twice that to the total irrigated lands (violet filled squares,, Fig. 02). But, it may not be simply a coincidence. Irrigated rice fields are used usually to cultivate rice at least twice (2) a year. Some farmers would try three (3) rice cultivations a year.
Also, the total of about 5Mha (in 2014) used for rice production would be contrary to Bureau of Agriculture data because there is only a total of just above 5Mha of arable lands ( of the total 9.7Mha agricultural lands. The second largest temporary crop cultivated is corn, and if the BASTAT data is correct, utilizes more than 2Mha of the total 5Mha arable land. While corn cultivation in the Philippines does not use irrigation, there are other crops that use water from existing irrigation systems, e.g., vegetable crops in the CAR region; most likely pineapple, banana, and other high value crops cultivated by multinational companies.
Eco-Friendly Irrigation Systems
Our own proposed projects will explore how to "irrigate" the remaining 8.0Mha of the 9.7Mha agricultural lands in the Philippines that remain unirrigated -- using techniques and technologies powered with sustainable energy sources that would be much less expensive construct and operate than conventional irrigation systems.
When water is made available throughout the year, rice production can be doubled or even tripled (based on yield potential of more recent rice varieties).
With recent progress in aerobic rice (see inverted red triangle Fig. rice strains that do not require flood irrigation, developed by the IRRI consortium, and by research in China), ecosystem intensification may double rice production and at the same time, in between rice cultivation use the same land to raise other short season crops. This will not only increase food production, not just rice but other crops using the same land area; but, more important.
Article write up in progress.