Search

In the Lao People’s Democratic Republic (PDR), increasing food security remains a challenge since smallholder agricultural systems, which are the main source of food production, are under serious threat due to poor soil fertility and climate variability. This study was undertaken in Lao PDR to investigate the impacts of organic and clay-based soil amendments on maize yield, total nutrient uptake, and soil properties. Structured field experiments were established over two consecutive years (2011 and 2012) with maize as the test crop at the Veunkham and Naphok sites. Ten treatments were applied in a randomized complete block design with three replications. The treatments were control, rice husk biochar (applied at a rate of 10 t ha−1), bentonite clay (10 t ha−1), compost (4 t ha−1), clay-manure compost (10 t ha−1), rice husk biochar compost (10 t ha−1), and their combinations. All treatments were applied in 2011. Significant (p< 0.05) treatment effects in maize grain yields, total nutrient uptake, and soil properties were observed. At Veunkham, differences between the control and amended soils in yield ranged from 0.9 to 3.3 t ha−1in 2011 and from 0.2 to 1.3 t ha−1in 2012, whereas differences at Naphok varied between 0.2 and 2.2 t ha−1in 2011 and from 0.2 to 1.7 t ha−1in 2012. At both sites, in most of the treatments, yields in 2012 were significantly (p< 0.05) lower than 2011; this was attributed to a late season drought. Differences between the control and amended soils in yield can be attributed to the improvements in total N and P uptake, soil pH, exchangeable Ca++and Mg++, and cation-exchange capacity following the application of soil amendments. The results of this study confirm that the soil amendments under consideration can be effective in improving agricultural productivity, while improving key soil properties indicating that soil amendments could be an option for intensification of agricultural productivity. [ABSTRACT FROM AUTHOR]

A crop growth simulation model was used to study the impact of climate change for the period 2010–2050 on water productivity of rainfed rice. In general, the results suggest that water productivity of rainfed rice may increase significantly in the upper basin in Laos and Thailand and may decrease in the lower basin in Cambodia and Vietnam. Significant net increases in water productivity can be achieved by applying simple adaptation options such as shifting the planting dates, applying supplementary irrigation, and increasing fertilizer inputs. [ABSTRACT FROM AUTHOR]