Improving Maize Yield, Total Nutrient Uptake and Soil Properties Through Organic and Clay-Based Soil Amendments in Lao PDR.

In the Lao PDR, increasing food security remains a challenge as food production is dependent on smallholder agricultural systems that are under serious threat due to poor soil fertility and climate variability. This study was undertaken in Laos to investigate the impacts of organic and clay-based soil amendments on maize yield, total nutrient uptake and soil properties. Two two-year (maize 2011, maize 2012) structured field experiments were established at the Veunkham and Naphok sites with 10 treatments each 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 only 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^-1 in 2011 and from 0.2 to 1.3 t ha^-1 in 2012, whereas differences at Naphok varied between 0.2 and 2.2 t ha^-1 in 2011 and from 0.2 to 1.7 t ha^-1 in 2012.  At both sites, in most of the treatments, yields in 2012 were significantly (p < 0.05) lower than 2011. Differences between the control and amended soils in yield can be attributed to the improvements in N and P use efficiency, soil pH, exchangeable Ca⁺⁺ and Mg⁺⁺, and CEC following the application soil amendments. This in turn indicates that soil amendments under consideration could be an option for sustainable intensification of agricultural productivity.

 

Key words: Agricultural production; Bentonite; Climate variability; Composted biochar; Land degradation; Rice husk biochar