Modelling water and solute processes and scenarios for optimisation of permanent raised bed systems in China, India, Pakistan and Indonesia

China, India, Indonesia, Pakistan

Dr Freeman Cook
Phone: (07) 3214 2840
Fax: (07) 3214 2855
Email: freeman.cook@csiro.au

$84,816

01/04/2006 - 30/09/2006

01/07/2007 - 30/09/2007

Dr Christian Roth

Permanent raised beds have been promoted to minimise the effects of waterlogging, reduce irrigation water and improve the biological and physical health of the soils - all for the purpose of increasing productivity of crops. But design criteria for permanent beds, in terms of infiltration and drainage, are not well developed and have frequently come about in relation to machinery specifications. Other concerns are correct fertiliser placement for nutrient and solute management and to minimise risk of build-up of salts. This project underpinned existing ACIAR projects by helping develop criteria for optimising bed design from analytical and numerical modelling of water and solute transport, and designing fertiliser placement strategies to maximise fertiliser usage and minimise leaching into ground water. Researchers also determined the likelihood of salinisation over time in different scenarios.

This report presented the results of simulations of water and solute transport in permanent raised beds (PRBs). As well as a generic research on modelling of raised beds the team undertook four case studies - one each in China, India, Pakistan and Indonesia - related to projects already funded by ACIAR. The work also included assimilation of data, estimation of soil properties, collation of climate data and estimation of crop rooting patterns. Simple models were developed for estimating optimal bed width for wetting by furrow irrigation, and drainage of beds when low permeability soils occur at the base of the beds.

The work highlighted some potential advantages and disadvantages of permanent raised beds and the need for further modelling and experimental work. The main advantages determined for permanent raised beds in this work were:
Good utilisation of water and fertilizers are possible if bed configuration is correct
Beds can provide much better aeration for all soils following irrigation, and especially clay soils

The main disadvantages for permanent raised beds that need further scrutiny were:
Bed width and wetting of the bed
Salt build up in the centre of beds
Leaching of salts and agro-chemicals to the groundwater

The research team recommended that a combined effort of modelling and experimental work was the best way to move forward with future research on permanent raised beds.