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August 2016 |
The prominence of nutrition as a component of a healthy lifestyle and increased longevity has increased consumer awareness of the variability that exist within the expanding food market. Choices between processed and fresh foods are made every day by consumers guided in part by nutritional benefits. Pro-health groups lobby against processed foods, suggesting that natural foods are better. Further distinction is present at the production level where organically produced foods have established a sizeable market share, even though prices are noticeably higher. According to the International Federation of Organic Agriculture Movements (IFOAM), “organic agriculture is a production system that sustains the health of soils, ecosystems and people. It relies on ecological processes, biodiversity and cycles adapted to local conditions, rather than the use of inputs with adverse effects. Organic agriculture combines tradition, innovation and science to benefit the shared environment and promote fair relationships and a good quality of life for all involved.” Although the definition is distinctive the appeal for organic foods emanates from a perceived health and safety benefit, which is not conclusive. Our market place presents us with a variety of options, differentiating healthy, nutritious foods not on nutritional composition but mostly on production system. This is especially true for whole unprocessed foods. Interestingly, an internet search of pro-health food stores in Trinidad and Tobago produces a number of hits indicating that there is a demand for healthy, nutritious foods. I have personally visited a few of these stores and the variety is expansive. However, the majority of products are packaged and not fresh whole foods. The Green Market is an example of one of the few places that markets the latter. So if you are wondering when or where does soil enter into this discussion on nutrition, well the simple answer to that is from the beginning. From very young we are taught that plants get their nutrients among other requirements from the soil, which puts two pieces of the puzzle together. Tragically, modern day commercial agriculture seems to depend less on the soil. In these systems the soil serves as an intermediary between commercial plant supplements (e.g. fertilisers) and crops, much like a lawyer, arguing a case for a client to a judge. At the extreme, soil can be totally removed in systems referred to as “soilless culture” (hydroponics). Regardless of the system of cultivation, a large population demands food in great supply. Efforts aimed at meeting this demand tend to compromise nutritional quality at the expense of increased yield. Low input agriculture (limited use of plant supplements) results in “nutrient mining” the un-replenished removal by crops of soil nutrients such as phosphorous, nitrogen and potassium. This is a form of chemical degradation which results in lower yields and foods of low nutritional quality. Such practices often result in farmers shifting cultivation from one location to another in search of improved natural fertility. This practice is prevalent on slopes and forested areas and is accompanied by increased prevalence of erosion and flooding on abandoned sites. Foods from such systems may contain low levels of essential nutrients especially micronutrients (Figure) and other health components such as antioxidants. At the other extreme, high input production incorporating use of synthetic or organic fertilisers may result in nutritionally better foods but may present nutritional imbalances as well as nutrient toxicity. Our soils play a critical role in buffering the availability and potential uptake of nutrient elements by plants. Plant uptake of harmful metal elements such as Cadmium, Arsenic and Selenium are partially governed by soil properties, indirectly affecting their content in foods. Notably, neither practice is sustainable. Research has shown that improving soil health and quality has a positive effect on crop nutrition. Implying that the hype associated with organic and other sustainable systems is well deserved. While I believe that such systems are the best option, implementation in the region is confounded by the tropical climate and soil variability. Organic matter is the key to sustaining soil quality and it is in short supply in the Caribbean, mainly reflective of a small livestock industry. Secondly, the year-round temperature (~ 30 °C) that brings tourist to our shores also accelerates the decomposition of organic matter, thus limiting its accrual in soils. The end effect is temporary, with the soil reverting back to an equilibrium state. Another and probably more technical limitation is the value placed on soil analysis and crop nutrition. Farmers seldom test their soils and when they do they are for many reasons, unable to formulate a soil fertility and crop nutrition plan. Such plans typically indicate measures required to improve and or maintain soil fertility for a particular target yield. Soil testing, plant analysis and crop visual nutrient symptom identification, when used together gives producers the best arsenal for ensuring nutritious foods. Research has shown that for many crop families a direct relationship exist between nutritional content of plant tissue and yield (including nutritional components). If plants have access to nutrients in the right proportions then not only will yield be optimized but foods will be highly nutritious. Unfortunately, traditional practices of topdressing with complete fertilizers at high frequencies and even the liberal application of organic manures contrast the science based management highlighted as crucial to soil quality. With this approach in mind, improving the nutritional composition of foods does not mean that we all have to eat organic. Identifying appropriate nutrients (whether inorganic or organic) and their amounts that should be supplied to the soils, along with appropriate application methods will greatly increase the nutritional quality of the foods we consume. The combination of organic and inorganic fertilizers is especially promising and appears to stimulate nutrient uptake. Research at The UWI, St. Augustine has shown increased yield and nutrient quality of lettuce through use of compost tea, applied to a growing media containing compost. For your information, compost tea is water in which finished compost has been steeped to cultivate a liquid fertilizer for plants. In closing, as we aim to live longer, healthier lives we need to pay attention to how our producers use the soil and align our policies towards encouraging increased nutritionally balanced foods, through soil diagnostic management. Dr Gaius Eudoxie is a lecturer in Soil Science at the Department of Food Production, Faculty of Food and Agriculture |
In today’s world of seemingly incurable diseases and high dependence on pharmaceutical drugs, a paradigm has emerged centred around alternative approaches to health, wellness and disease treatment. There is a new or rather renewed focus on holistic healthcare involving proper nutrition (diet) and physical activity geared mainly towards disease prevention, but also for treatment. Although my perspective may suggest a discussion on lifestyle changes, I wish to present another, more subtle relationship, one between the foods we consume and their origin, the soil.