The first prototype of the sprinkler irrigation system is a potential alternative irrigation method to increase water productivity without significant yield loss in aerobic rice production. This alternative must be explored to address water shortage and to enable pump irrigation in favorable upland. However, the water uniformity distribution of the sprinkler must be improved to avoid possible localized drought stress during crop growth and to increase the water use efficiency of rice. Although irrigation cost per m2 is projected to be lower using sprinkler than flush flooding, the economic advantage of aerobic rice
production using sprinkler irrigation system must be validated. The SIS should also be equipped with a filtration system to prevent clogging the nozzle during irrigation. This has to be based on the used size of the sprinkler nozzle to minimize the pressure loss consequence. It is further recommended that more on-farm field-testing should be conducted to verify initial results and determine the application to other crops to maximize its use.
Acknowledgment
This study was funded by the Climate Resiliency for Enhanced Agricultural Trade and Efficiency for Rice (CRP-002) program of DA-PhilRice.
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Introduction
In the Philippines, the major outcry in the industry and energy sectors is the ever-increasing cost and too much dependence on fossil fuel imports. Hence, the government is exploring alternative and renewable sources of energy such as solar, wind, hydro, and biomass. Biomass energy resources are derived from animals and plants, which can be converted into energy (Wise, 1983). Conversely, the call from the environmental side is the generation and utilization of huge amount of biomass from rice such as rice hull and rice straw. Rice straw is one of the main non-edible biomass resources in Asia including the Philippines (Ngo, 2011). The Philippine paddy rice production in 2018 was 19.07 M mt (PSA, 2019), which means that the rice straw production was 23.8 M mt based on the average rice grain: rice husk: rice straw ratio of 1.0:0.25:1.25 (Haefele et al., 2011).
Most of the time, rice straw is left on the fields and sometimes reincorporated in the soil, but a significant portion is considered a waste and occupies large areas of the fields, before its disposal through open-air burning or degradation. Mendoza (2015) stated that area-wise, crop residue burning still
dominates the Philippine agriculture landscape and 76% of rice lands and 64% of sugarcane lands are still burned. Migo-Sumagang et al. (2020) noted that, in the Philippines, farmers turned to open-field burning to drive away pests and to avoid the labor- intensive, manual gathering of rice straw. Casiwan et al. (2015) conducted a survey of rice stubble and straw management practices covering the 2009-2010 crop year in four major rice-producing provinces, namely: (1) Nueva Ecija – top rice producer; (2) Leyte – representing the Visayas and a province with an existing provincial ordinance banning rice straw burning; (3) North Cotabato – largest rice producer in Mindanao; and (4) Ilocos Norte – representing a province where there is an existing rice straw market.
They reported that 30% practiced open-field burning, 40% scattered and incorporated the straw into soil during land preparation, and the rest either left the straw in the threshing area to decompose or for feeding animals, or gathered and stacked it in one place for other purposes such as mulching for vegetable crops.
They found that the most cost-effective option for farmers is to incorporate stubble and straw in the soil more than 30 days before crop establishment.
They recommended looking for alternative uses of rice straw and finding ways to reduce the cost of