What a gungo peas! - Researcher finds that the plant reinvigorates mined-out lands

Protein-packed Gungo peas is known for providing culinary pleasure as part of several local dishes. But it is not well known that this legume also works wonders on impoverished soil.

This has been borne out in research conducted by Professor Mark Harris, an environmental geoscientist at Northern Caribbean University (NCU) in Mandeville.

Cajanus cajan - the botanical name for the gungo pea plant - has long been known to nourish some soils, but Harris sought to investigate the impact of the plant on mined-out bauxite lands, which are among the lowest in soil fertility.

His findings show that although phosphorus, an essential element for plant and animal nutrition, is present in bauxite soil, it is unable to nourish plant life in those circumstances.

"As soils weather, the proportion of aluminium and iron oxides increases, and they are positively charged," said Harris.

"On the other hand, the phosphate (phosphorus) is negatively charged and is, therefore, neutralised by the chemical effects of the aluminium and iron," added Harris

It is at this stage that the gungo pea plant does its work of science. "The root of the gungo exudes piscidic acid that unravels the iron and aluminium-phosphate complexes," Harris explained.

He pointed out that the virtuous effect of the gungo plant was detected in a narrow zone (less than 35mm) around the root. But this was offset by the gungo root extending not vertically, but horizontally, in the soil. Hence, close planting of the long-rooted, drought-resistant plant would replenish the upper soil layers used by crop plants and increase soil fertility.

Harris noted that although decaying matter such as leaves and manures can increase phosphorus in impoverished soil, only heavy quantities would be useful to soil with locked-up phosphorus.

But he argued that with large quantities of decaying organic matter rarely available, the "potential usefulness of phosphorus-releasing plant species such as the gungo pea is clear".

Although the findings are just being released locally, the research was conducted in 2016 and appeared that year in Harris' book, titled Geobiotechnological Solutions to Anthropogenic Disturbances: A Caribbean perspective, published by Switzerland-based Springer-Nature International Publishing.

Noting that similar phosphorus deficiencies exist in vast, unused fine clay lands of Clarendon and St Catherine, Harris stated: "The humble legume promises an economic invigoration of mined-out bauxite lands, and the vast wastelands of St Catherine and Clarendon, if these published research findings are applied to such locations."

The NCU researcher recommended the large-scale planting of gungo pea to increase the economic status of Jamaicans in many disadvantaged communities with infertile, drought-prone soils, as well as to alleviate poor nutrition among school-age children.