Soil management for raising crop water productivity in rainfed production systems in Lao PDR

This study investigated the impacts of organic- and clay-based soil amendments, and their combinations on crop water productivity (CWP) using maize as a test crop. On-station field trials were established over two consecutive years at the Naphok and Veunkham sites in Laos. At each site, 10 treatments were applied in a randomized complete block design with three replications. The treatments were control, rice husk biochar (10tha(-1)), bentonite clay (10tha(-1)), compost (4tha(-1)), clay-manure compost (10tha(-1)), rice husk biochar compost (10tha(-1)), bentonite clay + biochar, bentonite-clay + compost, biochar + compost, and bentonite clay + biochar + compost. All treatments were applied in 2011. Significant (p<0.05) treatment effects in CWP and growing period evapotranspiration were determined. At Naphok, differences between the amended and control plots in CWP varied between 0.1 and 0.6kgm(-3) in 2011 and from 0.1 to 0.4kgm(-3) in 2012, whereas differences at Veunkham varied between 0.3 and 1.0kgm(-3) in 2011 and from 0.05 to 0.29kgm(-3) in 2012. At both sites, CWP in 2012 was significantly lower than 2011. Our results illustrate that organic- and clay-based soil amendments improve CWP, indicating that soil-based interventions could be suitable options for improving agricultural productivity.