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In iron toxic laterite soil of Kerala, the major soil related constraints affecting rice production are acidity and toxicity of metals like iron (Fe), aluminium (Al) and manganese (Mn). In Kollam district approximately 60 per cent of area under rice is coming under iron toxic iron laterite soil. The presence of high concentration of these metals in soil hinders the absorption of other nutrients leading to poor nutrient use efficiency. A suitable nutrient management system which reduces the toxic level of these metals prevalent in low pH soil, will certainly improve the yield of rice. The trial consisted of three technology options viz., farmers practice i.e., unscientific use of high analysis fertilizers (TO1), recommended practice i.e., 5 t/ha OM + 90: 45: 45 kg N: P: K/ha +600 kg lime/ha (TO2) and alternate practice i.e., 90: 45: 120 kg N: P: K/ha +OM 5 t/ha + 150 kg lime/ha+100 kg silica/ha (TO3). The study revealed that compared to the technology TO1 and TO2, the technology option TO3 (OM 5 t/ha+ 90: 45: 120 kg N: P: K/ha + 150 kg lime+100 kg silica) gave significantly higher grain and straw yield i.e., 6.61 t/ha (17.62%) increase in grain and 9.29 t/ha (20.65%) increase in straw over recommended practice (TO2). Benefit cost ratio was also highest for this treatment (2.26). The lowest incidence of pests was recorded in silica applied plots. This shows that in addition to yield enhancement, this technology has an additional benefit i.e., reduction of pest incidence. Hence the outcomes of this farmer participatory experiment emphasized the importance of the special nutrient package for yield increase in rice under iron toxic laterite soils. The feedback of the farmers who visited the trial plots was positive and they recorded that silica application has increased the growth and number of productive tillers. They also observed that silica application reduced the incidence of pests.
Yadav et al. (Sun,) studied this question.