SLU news

Improving water use efficiency in small-scale maize production systems

Published: 24 May 2017
Emilio Magaia washing maize root systems during his field work in Mozambique. Photo: Armand Leonardo.

Maize yields in sub-Saharan Africa have been at the lower end of the global range for decades. A new thesis by Emilio Magaia presents result for improved crop water use efficiency in semi-arid regions through better soil and water management practices.

Sub-Saharan Africa is in dire need of new technologies to increase water use efficiency in rainfed agricultural systems. Today, smallholder farmers use little or no purchased fertilisers or irrigation and are using hand tools for land preparation. The main challenge is to feed the population with existing resources and prevailing agricultural technologies.

Improving crop yield in rainfed cultivations

– Maize yields in sub-Saharan Africa have been at the lower end of the global range for decades, probably because smallholder farmers use manual cultivation techniques and little or no purchased inputs or irrigation. There is a great interest in increasing maize grain yield through a combination of different soil and water management strategies in Southern Africa, says Emilio Magaia.

In his doctoral thesis, Emilio studied the possibilities to increase maize grain yield in rainfed agriculture. The impact of supplemental irrigation, fertiliser application and three different tillage methods (hand hoeing, strip tillage, disc tillage) on maize grain yield were investigated in a sandy loam soil in a semi-arid region of Mozambique.

Emilio Magaia installs profile access tubes into the soil. Photo: Armando Leonardo.
Strip lines are made in the field. Photo: Emilio Magaia.
One of the maize fields in the study. Photo: Emilio Magaia.

The recommended fertilisation rates must be updated

Emilio found that the root abundance decreased down the soil profile. Root and shoot growth were influenced mainly by water supply and fertiliser application.

– My results show that the actual recommended nitrogen fertiliser rate for maize in Mozambique is not suitable for rainfed semi-arid regions. The optimal fertiliser rate should be much lower. In addition, the fertiliser amount should be adjusted to climate variability. In very dry years the application of fertiliser can be suspended, says Emilio.

Important to take a combined approach to fertilization and water management

The best option to increase maize production and water use efficiency is through supplemental irrigation and fertiliser application. It is important to take a combined approach to water supply and fertiliser application.

– Agriculture is the main contributor to the economy in Mozambique, employing over 80% of the population. I hope that the results from my thesis will help improving crop water use efficiency through better soil and water management practices, says Emilio.