An Opportunity for Legume Farmers to Reduce Urea Fertilizers in Cultivations

In Guyana, legumes are consumed on a daily basis. Bora, black-eye, red-peas, pigeon peas and beans appear on Guyanese plates every day and most of it is produced by local farmers.

All farmers know that apart from water, crops need plant food. These plant foods come in the form of fertilizers containing mainly nitrogen, phosphorus and potassium. As such, they are familiar with the fertilizers: urea, TSP and muriate of potash.

Legume farmers are aware that the main plant food used to produce blackeye, bora and other legumes is urea.  Many farmers will tell you that without the use of urea they may or may not produce a good crop. They will also tell you that the plants started well with healthy green leaves. However, these leaves may soon turn pale green or yellow, and the crop will die or produce poorly. They may or may not be able to explain the reason behind this type of crop failure, however, the National Agricultural Research and Extension Institute (NAREI) has the answers and the solution for successful and economic production of legumes.

The legume is a very special crop. While all plants need nitrogen for healthy growth and production, legume is the only crop with the ability to supply itself with the nitrogen it needs. How does this happen? The plant gets its nitrogen from the air with help from special bacteria in the soil called rhizobia. This is evident by the presence of small seed like attachments on the root of the plant called nodules. If on cutting a nodule a red colour is seen, then the nodule is producing nitrogen for the plant.  Of course the amount of nitrogen received by the legume will depend on the presence of the rhizobia bacteria in the soil, and the closeness of the relationship between the bacteria and the plant. This explains why even without the use of nitrogen a crop of legume may give good produce.

But, should legume farmers plant and hope for good production? Surely all legumes farmers and consumers will say no, and NAREI has the solution by providing a substitute for urea. Over the years, NAREI has captured, tested and stocked many useful rhizobia bacteria strains. These strains are used to make rhizobia inoculum and many farmers have benefited from their correct use. This inoculant can be had from NAREI for free and farmers will have the benefit of no cost for urea fertilizer and good legume production.

The rhizobia inoculant is environmentally friendly as it is made and distributed as a powdered charcoal substance. The inoculant requires small quantities – 14 grams of inoculant to one kilogram of seeds – for it to be effective. To maintain the quality of the inoculant, inocula collected from NAREI must be stored away from sunlight and in a cool place. To obtain optimum results, inocula should be applied to moist seeds, which should be planted in moist soil in the cool of the day.

The results of field trials conducted by NAREI showed that by using rhizobia inoculant, red peas farmers will save on the cost of 100 kg/ha of urea and obtain the same yield.