R. Vimal Kumar
Magnesium deficiency in soil threatens yield and quality
TUTICORIN: Cotton farmers in the district are worried lot as magnesium deficiency in the soil is threatening the yield and quality on a large scale.
According to official sources, about 20 percent of the crop raised on 7,000 hectares of rainfed area spread over Kovilpatti, Vilathikulam, Ettayapuram and Kovilpatti blocks during the current season had already been affected.
The deficiency was detected recently by a team of experts comprising V. Subramanian, Chief Scientist, and K. Baskar, Soil Scientist, from Agriculture Research Station (ARS), Kovilpatti.
Farmers had complained that leaves of the plants were quickly turning reddish purple.
Subsequent studies revealed that magnesium content in the plants was less than 0.1 percent.
The potassium to magnesium ratio was also found to be 8:1 in the affected regions.
"A healthy plant normally has 0.6 to 0.9 percent of magnesium and the potassium to magnesium ratio should not exceed 5:1," says Mr. Subramanian.
The disparity in the magnesium ratio occurred owing to variation in soil moisture content and high soil temperature ranging from 30 to 32 degree celsius even at a depth of 30 cm, due to lack of adequate rainfall.
"Presence of the right amount of magnesium plays an important role in photosynthesis. Deficiency affects a plant's respiration, phosphate metabolism and activation of enzymes, resulting in `death' of the crop," he says.
ARS scientists are telling the farmers to spray five gm of magnesium sulphate (epsom salt) diluted in one litre of water on 45th and 60th days of sowing or basal application of 25 kg of magnesium sulphate for every hectare on a war footing.