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Alternate wetting and drying irrigation maintained rice yields despite half the irrigation volume, but is currently unlikely to be adopted by smallholder lowland rice farmers in Nepal

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ABSTRACT

Alternate wetting and drying (AWD) irrigation can save water while maintaining rice yields, but in some countries its adoption by farmers remains limited. Key knowledge gaps include the effect of AWD on early vegetative vigor and its relationship with yield; the effects of AWD on yield and water use efficiency of local cultivars used by smallholder farmers; and the socio‐economic factors influencing current irrigation scheduling. To address these questions, an on‐farm field trial of dry‐season (chaite) rice, comparing two locally important cultivars (Hardinath‐1 and CH‐45) under AWD imposed from 1 week after transplanting to flowering and continuous flooding (CF), was carried out in Agyauli in the central Terai region of Nepal, and triangulated with social research methods exploring the rationale for current irrigation scheduling and perceptions of AWD. Although AWD plots received on average 57% less irrigation water than CF plots, yields did not significantly differ between irrigation treatments, indicating that AWD could considerably enhance crop water use efficiency in this region. In the earlier flowering, more vigorous CH‐45, there were no treatment differences in any yield component while in the later flowering Hardinath‐1, an 11% decrease in filled grain number was compensated by a 14% increase in the percentage of effective tillers per hill. Although leaf elongation rate on the main tiller did not differ between treatments, tillering and green fraction (a measure of canopy closure) were significantly higher under AWD. Surveys established that most local farmers are already using a local adaptation of AWD to modify irrigation volumes, in some cases in response to a limited and unreliable water supply. However, farmers have few direct incentives to reduce overall water use under current water governance, and formal AWD practices are therefore unlikely to be adopted despite their viability as a water‐saving irrigation technique.

No MeSH data available.


Related in: MedlinePlus

Graphs showing responses as the percentage of 101 respondents giving that response to the following questions: (A) How often do you flood the field? (B) Can you always access the irrigation water you need? (C) Choices 1, 2 and 3 were choice experiments in which respondents were asked to choose between continuous flooding (CF), alternate wetting and drying (AWD) and local practices; two respondents gave no replies, and one respondent answered “don't know” to Choice 1.
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fes358-fig-0006: Graphs showing responses as the percentage of 101 respondents giving that response to the following questions: (A) How often do you flood the field? (B) Can you always access the irrigation water you need? (C) Choices 1, 2 and 3 were choice experiments in which respondents were asked to choose between continuous flooding (CF), alternate wetting and drying (AWD) and local practices; two respondents gave no replies, and one respondent answered “don't know” to Choice 1.

Mentions: Most respondents flood their rice fields every ~2–3 days (55%). Some 15% irrigate daily, and 21% weekly (Fig. 6A), while others irrigate depending on soil type and elevation relative to water sources. Most respondents flood their field based on changes in soil water status (62%) or the availability of water (35%, particularly high amongst kulo users). An overwhelming 93% of respondents use the same irrigation scheduling every year. Those who do change their scheduling are influenced by interannual variability in the timings of rain and panicle development, and noted that their scheduling depends on timetabling of load‐shedding (nonavailability of electricity) and turn‐taking between farmers. Crucial times for the crop to have access to water were stated as during tillering (88% of respondents), a few days after transplanting (25%) and after weeding (14%). Respondents were aware of the need to increase the efficient use of available water by building bunds properly (74%), mending holes in them (65%) and irrigating the field carefully (12%). No respondents store water for irrigation.


Alternate wetting and drying irrigation maintained rice yields despite half the irrigation volume, but is currently unlikely to be adopted by smallholder lowland rice farmers in Nepal
Graphs showing responses as the percentage of 101 respondents giving that response to the following questions: (A) How often do you flood the field? (B) Can you always access the irrigation water you need? (C) Choices 1, 2 and 3 were choice experiments in which respondents were asked to choose between continuous flooding (CF), alternate wetting and drying (AWD) and local practices; two respondents gave no replies, and one respondent answered “don't know” to Choice 1.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4998133&req=5

fes358-fig-0006: Graphs showing responses as the percentage of 101 respondents giving that response to the following questions: (A) How often do you flood the field? (B) Can you always access the irrigation water you need? (C) Choices 1, 2 and 3 were choice experiments in which respondents were asked to choose between continuous flooding (CF), alternate wetting and drying (AWD) and local practices; two respondents gave no replies, and one respondent answered “don't know” to Choice 1.
Mentions: Most respondents flood their rice fields every ~2–3 days (55%). Some 15% irrigate daily, and 21% weekly (Fig. 6A), while others irrigate depending on soil type and elevation relative to water sources. Most respondents flood their field based on changes in soil water status (62%) or the availability of water (35%, particularly high amongst kulo users). An overwhelming 93% of respondents use the same irrigation scheduling every year. Those who do change their scheduling are influenced by interannual variability in the timings of rain and panicle development, and noted that their scheduling depends on timetabling of load‐shedding (nonavailability of electricity) and turn‐taking between farmers. Crucial times for the crop to have access to water were stated as during tillering (88% of respondents), a few days after transplanting (25%) and after weeding (14%). Respondents were aware of the need to increase the efficient use of available water by building bunds properly (74%), mending holes in them (65%) and irrigating the field carefully (12%). No respondents store water for irrigation.

View Article: PubMed Central - PubMed

ABSTRACT

Alternate wetting and drying (AWD) irrigation can save water while maintaining rice yields, but in some countries its adoption by farmers remains limited. Key knowledge gaps include the effect of AWD on early vegetative vigor and its relationship with yield; the effects of AWD on yield and water use efficiency of local cultivars used by smallholder farmers; and the socio‐economic factors influencing current irrigation scheduling. To address these questions, an on‐farm field trial of dry‐season (chaite) rice, comparing two locally important cultivars (Hardinath‐1 and CH‐45) under AWD imposed from 1 week after transplanting to flowering and continuous flooding (CF), was carried out in Agyauli in the central Terai region of Nepal, and triangulated with social research methods exploring the rationale for current irrigation scheduling and perceptions of AWD. Although AWD plots received on average 57% less irrigation water than CF plots, yields did not significantly differ between irrigation treatments, indicating that AWD could considerably enhance crop water use efficiency in this region. In the earlier flowering, more vigorous CH‐45, there were no treatment differences in any yield component while in the later flowering Hardinath‐1, an 11% decrease in filled grain number was compensated by a 14% increase in the percentage of effective tillers per hill. Although leaf elongation rate on the main tiller did not differ between treatments, tillering and green fraction (a measure of canopy closure) were significantly higher under AWD. Surveys established that most local farmers are already using a local adaptation of AWD to modify irrigation volumes, in some cases in response to a limited and unreliable water supply. However, farmers have few direct incentives to reduce overall water use under current water governance, and formal AWD practices are therefore unlikely to be adopted despite their viability as a water‐saving irrigation technique.

No MeSH data available.


Related in: MedlinePlus