Interaction between contrasting rice genotypes and soil physical conditions induced by hydraulic stresses typical of alternate wetting and drying irrigation of soil

Background and aims: Alternate wetting and drying (AWD) saves water in paddy rice production but could influence soil physical conditions and root growth. This study investigated the interaction between contrasting rice genotypes, soil structure and mechanical impedance influenced by hydraulic stresses typical of AWD. Methods: Contrasting rice genotypes, IR64 and deeper- rooting Black Gora were grown in various soil conditions for 2 weeks. For the AWD treatments the soil was either maintained in a puddled state, equilibrated to −5 kPa (WET), or dried to −50 kPa and then rewetted at thewater potential of −5 kPa (DRY-WET). There was an additional manipulated macropore structure treatment, i.e. the soil was broken into aggregates, packed into cores and equilibrated to −5 kPa (REPACKED). A flooded treatment (puddled soil remained flooded until harvest) was set as a control (FLOODED). Soil bulk density, penetration resistance and X-ray Computed Tomography (CT) derived macropore structure were measured. Total root length, root surface area, root volume, average diameter, and tip number were determined by WinRhizo. Results: AWD induced formation of macropores and slightly increased soil mechanical impedance. The total root length of the AWD and REPACKED treatments were 1.7–2.2 and 3.5–4.2 times greater than that of the FLOODED treatment. There was no significant difference between WET and DRY-WET treatments. The differences between genotypes were minimal. Conclusions: AWD influenced soil physical properties and some root characteristics of rice seedlings, but drying soil initially to −50 kPa versus −5 kPa had no impact. Macropores formed intentionally from repacking caused a large change in root characteristics

A multi-stakeholder partnership for the dissemination of alternate wetting and drying water-saving technology for rice farmers in the Philippines

To address issues of water scarcity and food security for sustainable rice farming and increasing production, a water-saving technology called alternate wetting and drying (AWD) was disseminated in the Philippines. This study assessed the impact of facilitating a network of stakeholders on disseminating AWD in irrigated rice systems in the Philippines. It used both qualitative and quantitative data collected from 2002 to 2012 in study sites in the country. Engaging multi-stakeholders in adaptive research, training, and dissemination facilitated the process of more interaction by partners. All partners joined a knowledge and dissemination alliance for scaling out AWD activities. This in turn effected a policy outcome, and the synergetic interactions of each partner within and outside the current network fast-tracked the dissemination process and adoption of AWD by farmers. The AWD practice resulted in an increase in irrigated rice area but not necessarily in rice production and farmers’ income. It also reduced labor and fuel consumption, especially in deep-well irrigation systems

Yield gaps in rice-based farming systems: Insights from local studies and prospects for future analysis

The important contribution of rice to global food security requires an understanding of yield gaps in rice-based farming systems. However, estimates of yield gaps are often compromised by a failure to recognize the components that determine them at a local scale. It is essential to define yield gaps by the biological limitations of the genotype and the environment. There exist a number of methods for estimating rice yield gaps, including the use of crop growth simulation models, field experiments and farmer yields. We reviewed the existing literature to (i) assess the methods used to estimate rice yield gaps at a local scale and to summarize the yield gaps estimated in those studies, (ii) identify practical methods of analysis that provides realistic estimates of exploitable rice yield gaps, and (iii) provide recommendations for future studies on rice yield gaps that will allow accurate interpretation of available data at a local level. Rice yield gap analysis can be simplified without sacrificing precision and context specificity. This review identifies the comparison of the attainable farm yield (the mean of the top decile) with the population mean, as a practical and robust approach to estimate an exploitable yield gap that is highly relevant at the local level, taking into account what is achievable given the local socio-economic conditions. With this method we identified exploitable yield gaps ranging from 23 to 42% for one particular season in four different rice growing areas in Southeast Asia. To enable accurate estimation and interpretation of yield gaps in rice production systems, we propose a minimum dataset needed for rice yield gap assessment. Future studies on rice yield gaps should consider the region, season and crop ecosystem (e.g. upland rainfed, lowland irrigated) as a minimum to facilitate decisions at a local level. In addition, we recommend taking into account the cultivar, soil type, planting date, crop establishment method and nitrogen application rates, as well as field topography and toposequence for rainfed systems. A good understanding of rice yield gaps and the factors leading to yield gaps will allow better targeting of agricultural research and development priorities for livelihood improvement and sustainable rice production.</p

Replication Data for: Adoption and impact of alternate wetting and drying water management for irrigated rice production in the Philippines

Data files for "Adoption and impact of alternate wetting and drying water management for irrigated rice production in the Philippines