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Explora: Environment
and Resource Climate suitability of AWD practice

values (1 – 5 mm/day), there is excess water balance, organic-rich soils for nutrient availability and improves
hence unsuitable for AWD practice. With the increasing soil water retention, which is key for paddy rice growth
water scarcity issues in Uganda due to climate variability and survival during the non-flooded periods of AWD
and prolonged droughts, AWD would optimize irrigation practice. 25,48 On the contrary, the excess OCS can lead to
water use, reducing dependence on erratic rainfall. Our increased methane emissions. Likewise, AW is the major
findings indicate that AWD is suitable for all dry seasons determinant of AWD suitability, affecting the soil’s ability
and during the rainy season when precipitation is below to retain and supply water to crops between irrigation
20 mm/day. This is significant for large schemes, including cycles. Higher AW ensures sufficient soil moisture for rice
Kibimba and Doho, to improve water management and growth within the non-flooded cycles of AWD practice.
paddy rice expansion to meet the growing demand. Therefore, areas with high AW show greater resilience to
periodic drying phases with AWD application.
Nevertheless, groundwater table interactions with AWD
irrigation practice play a critical role in water management, In addition, the soil texture influences water retention
soil aeration, and crop health. AWD drying and re-wetting and percolation. The soils with low AW (e.g., sandy soils)
cycles influence groundwater recharge and soil moisture drain quickly, affecting the irrigation frequency of AWD
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dynamics. With the shallow groundwater table, capillary to minimize crop stress. Our findings suggest that AWD
rise can supplement rice water requirements, reducing works best in soils with a moderate AW range, balancing
the need for irrigation. However, in regions with deep water retention with adequate drainage to prevent over-
groundwater tables, the effectiveness of AWD depends saturation. This is a characteristic of clay and sandy clay
heavily on precipitation and percolation rates. Our findings loam soils with high water-holding capacity and balance
indicate that AWD is more suitable when percolation between water retention and drainage.
rates exceed 5 mm/day and precipitation ≤20 mm/day, Our study on climate AWD suitability in Uganda
enhancing optimal soil moisture retention and aeration aligns perfectly with several studies conducted in Asia
while minimizing excess water loss. In addition, AWD and West Africa, highlighting its global relevance as a
reduces methane emissions through periodic oxygenation climate-smart water management strategy for paddy rice
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of the soil and reduces anaerobic decomposition. cultivation. Compared to traditional flooding (CF), AWD
However, its impact on groundwater levels varies by has been extensively studied and promoted as a sustainable
soil type and climatic conditions, which is missing in water management technique in Asia, particularly in the
Uganda. This necessitates local assessments of the effect Philippines, Thailand, and Indonesia. Studies by Sander
of AWD and groundwater interactions to optimize AWD et al. found that AWD reduced methane emissions
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implementation in different ecological zones. by 48% in the Philippines while maintaining or even
On the other hand, the potential suitability of the improving rice yields. Likewise, a study in Thailand
“locations” distribution was influenced by the “predictors” reported a significant reduction in methane and nitrous
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importance and sensitivity analysis. Our findings show oxide emissions without compromising rice productivity.
that CRFVOL, OCS, the accessible water (AW), EXK These studies support our findings that AWD suitability
and TWI and rainfall of the warmest quarter (BIO18) was linked to precipitation levels and soil percolation rates
were the top predictors that significantly influenced and is crucial given the increasing water scarcity in Uganda
the suitability of AWD practice. These findings differ due to climate variability. 9
slightly from research by Sander et al., in which the Similarly, percolation rate is a critical factor in
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suitability was primarily affected by precipitation and soil determining AWD suitability where soils with high
percolation rates. The reliability test of the distribution clay contents and low percolation rates have low water
model (Figure 3), Jackknife test (Figure 4) and response drainage, which leads to waterlogging (creating anaerobic
curves indicate that coarse fragments of CRFVOL show a conditions) and increases methane emissions. Moreover,
decrease in AWD suitability with a maximum value of 75% high percolation rates (>5 mm/day) improve soil aeration,
and a rapid decrease between 0% and 5%. Similarly, OCS reducing methane emissions and allowing rice roots to
has a peak suitability value of up to 100% at 10 tons/ha. access moisture while preventing prolonged flooding.
8
The peak suitability is associated with a soil clay content These, together with TWI, determine water accumulation
of approximately 75%, a soil bulk density (BDCRIM) not in the fields. The high TWI values indicated low-lying
exceeding 175 kg/m , and a reduction to zero suitability at areas, where AWD was less effective due to excessive
3
57 tons/ha. The BIO18 indicates the maximum suitability water retention. Furthermore, our findings suggest that
of AWD practice for precipitation between 96 mm and all constant Pot values for December, January, and
pc
425 mm. The high OCS influences microbial activities in February (dekads 1 – 6) are typically suitable for AWD

Volume 2 Issue 2 (2025) 13 doi: 10.36922/EER025040005