Effect of application of silicate and phosphate on phosphorus availability during the growth of corn (Zea mays L.) seedlings in an ultisol

Adding onions to the soil exchange surface can minimize fixation of phosphorus by Al and Fe-hydrous oxide. One way to minimize this is by adding silicate. The effectiveness of fixed-phosphate to change into available form is affected by rate and time of application of silicate and phosphate. This study was conducted: a) to evaluate the effect of timing and rate of application of silicate and phosphate on phosphorus availability during the growth of the corn seedling, and b) to evaluate the effect of timing and rate of application of silicate and phosphate on dry matter yield and concentration of phosphorus in the plant. In experiment without corn grown, the addition of silicate and 22 ppm P over control significantly increased available phosphorus of the soil, from 0.70 to 6 ppm P, decreased soil extractable Fe, from 107 to 85 ppm Fe, and increased soil extractable silicate, from 22 to 25 ppm Si. Increasing the rate of silicate from 110 to 330 and 220 to 330 ppm silicate at 22 ppm P significantly increased soil available phosphorus, from 5 to 7 ppm P and from 6 to 7 ppm P, respectively, decreased soil extractable Fe, from 93 to 75 ppm Fe and from 87 to 75 ppm Fe,respectively. In experiment where corn was grown, the addition of silicate and 320 ppm P over growth significantly increased soil pH from 5.80 to 6.14, decreased soil extractable Fe from 97 to 46 ppm Fe, increased soil available phosphorus from 0.60 to 65 ppm P, increased phosphorus of tissue from 0.11 to 0.17 ppm P, increased plant height of corn from 56 to 128 cm and from 115 to 174 cm at 4 weeks after planting and at harvest, respectively, and increased dry weight of corn from 21 to 66 g/pot. Increasing the rate of silicate from 250 to 500 ppm Si applied at day-1 and applied at day-30 at 320 ppm P significantly increased soil pH, from 6.07 to 6.40 and from 5.90 to 6.23 increased soil available phosphorus, from 71 to 135 ppm P and from 43 to 135 ppm P, r espectively. It is concluded that the addition of silicate and phosphate significantly increased soil available P. total P of tissue, plant height, and dry weight of corn. The increasing availability of soil P is caused by increasing soil pH and decreasing soil extractable Fe.