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

Abstract

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⁻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; 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.

KEYWORDS:

• agricultural production
• bentonite
• climate variability
• composted biochar
• land degradation
• rice husk biochar

ACKNOWLEDGMENTS

We are grateful to the National Agricultural and Forestry Research Institute (NAFRI), Naphok Industrial and Oil Crops Research Center, and Veunkham Clean Agriculture Development Center for logistical support.