In recent times we have been hearing constantly of the need to reduce costs of production of crops as well as the need to reduce our dependence on imported inputs. There are a number of things we can do in this regard, but few farmers seem to be taking this issue seriously.
The news of the production of compost from garbage at the recently launched Sustainable Barbados Recycling Centre Inc at Vaucluse, St Thomas should be welcomed by farmers, both sugar and non-sugar. Our soils over the years have become depleted of organic matter. We know that compost is beneficial to the soil through improvement of texture and water holding capacity as well as the addition of nutrients such as nitrogen, phosphate, potassium , trace elements and beneficial micro organisms. Trials in the past have demonstrated that yield increases of around 19% are possible in sugar cane as a result of addition of compost. But as has been mentioned in this column before, the application equipment for compost is expensive, and government may have to think of giving a rebate on this equipment to encourage farmers to use it.
Weed control is an expensive part of growing a crop. Measures like growing khus khus around borders of fields have been recommended by the Agronomy Research and Variety Testing Unit (ARVTU) in their Sugar Cane Growers Manual 1997. This stops serious weeds like Devilâ€™s Grass from encroaching on fields from cart roads, while at the same time preventing soil erosion. Of course the khus khus must be cut regularly to keep it in check and prevent its interference with the operation of mechanical harvesters. This weed control method is environmentally friendly since chemical use and the consequent effects on our ground water supply are minimized.
Another measure which could be beneficial to both sugar cane and non-sugar cane growers is the use of strip tillage as opposed to traditional (full) tillage. This tillage method was experimented with since 1983 in sugar cane production where its aim was to retain the trash blanket in plant cane fields, thus reducing soil erosion, improving moisture retention by the soil and reducing weeds. It involves the application of glyphosate herbicide to the cane stumps to kill them, then creating a thoroughly tilled furrow between the old cane rows and leaving the trash intact. It is felt that in spite of the increased cost of glyphosate in recent times, the cost of the operation would be significantly lower than the traditional full cultivation method.
While experimental work with this tillage method has been mainly with sugar cane, we think that this should be looked at for non-sugar crops like cotton, pigeon peas, sweet peppers, tomatoes, eggplant, okra, corn, cabbage and particularly the cucurbit crops which do well in soils with high organic matter. The natural trash mulch could replace the method of imported plastic mulch used in recent years for a number of vegetable crops. The expense of distributing natural mulch would be avoided since it would already be in place.
Bunchy Top disease has been a perennial problem for paw paw growers in Barbados, particularly in recent years when yields have sometimes been reduced to zero. A Think Tank on viruses hosted by BSTA about two years ago led to the collection of available data on the Bunchy Top disease and possible methods of control. Included in the information discussed was work done by Chinnery and Waterman (1995) who noted that roots of many papaya plants with Bunchy Top had nematode galls, and that levels of root colonization by Vesicular Arbuscular mycorrhizal fungi were negatively correlated with the magnitude of disease symptoms. These mycorrhizae are the most abundant of a group of symbiotic fungi that infect plant roots and increase the nutrient and water uptake of their hosts. It is possible therefore that planting of paw paws in fields coming out of sugar cane, using the strip tillage method where the trash blanket provides a source of organic matter when it decomposes, could result in increased mycorrhizae and reduced Bunchy Top.
Furthermore, since Peter Dunfield, a McGill university student, is quoted in the ARVTU Sugar Cane Growers Manual as finding an increase in mycorrhizal presence in plant cane after the application of compost, it is felt that application of compost to the paw paw plants could provide additional protection against Bunchy Top.
Hopefully, farmers will take some initiative and try these environmentally friendly methods of reducing costs and reliance on imported inputs, thus helping themselves and the environment at the same time.