KOCHI: Have you ever wondered why our lakes and rivulets are always infested with invasive aquatic plants and weeds, causing inconvenience to people and aquatic life!
Don’t get surprised next time when you see weed-infested water-bodies, because we are responsible for what they are.
A study conducted by the State Government underlines the fact that 80 per cent of the soils in Kerala carries exceedingly high level of phosphorus, as a result of application of large quantities of N, P and K fertilisers in the fields. This causes excessive growth of algae and weeds in streams and lakes as they are a natural catch basin for runoff.
The survey, which involved analyses of over 2.5 soil samples collected from different parts of the State, revealed that while phosphorus content is very high in our soils, there is deficiency of nutrients like nitrogen (24 per cent), potash (33), calcium (40), magnesium (74), sulphur (30), zinc (12), copper (15) and boron (60). The unmindful use of large quantities of N, P and K fertilisers for increasing crop production has led to soil nutrient imbalance, especially with respect to micro-nutrients.
Speaking to ‘Express’, Vellanikkara College of Horticulture professor and radiotracer laboratory head Dr P Sureshkumar said only a healthy ecosystem could sustain healthy soil capable of carrying out its physical, chemical and biological functions in an optimum manner.“There are several reasons for the nutrient imbalance in our soils, including unmindful use of fertilisers.
“Besides, the peculiar topography of the State is conducive for erosion of top soil in upper reaches, and sedimentation in lakes and ponds during high rainfall. This not only creates nutrient imbalance in the soil, but also pollutes the water bodies, disturbing aquatic ecosystems and causing eutrophication,” he said.
The Kerala Agricultural University (KAU) is in the process of preparing a detailed soil map of Kerala by dividing the State into 23 agro-ecological units. Once the project is completed, it will provide vital information to farmers about the nature of soil and the level of nutrients present in each unit, facilitating conservation of soil based on its PH value in each unit.
“The agro-ecological unit is characterised by distinct responses to the macro-elements as reflected in the vegetation/soils and usage of land for agriculture,” he said, adding that information on the fertility status of soil is necessary to alleviate yield loss due to deficiency/toxicity of various nutrient elements.
The officials also admitted that though the study was conducted two years ago and a slew of measures, including reduction of phosphorus usage, were adopted there is no visible improvement yet.