MAF scientists find better phosphate spread method

Waimarino Bulletin, Volume 6, Issue 266, 6 December 1988, Page 7

MAF scientists find better phosphate spread method

Scientists at MAF's Ruakura Agricultural Centre have made a discovery which could revolutionise the use of rock phosphate fertilisers. They've found rock phosphate dissolves faster when mixed and spread with other soluble phosphate fertilisers. This means the phosphate contained in the rock b e c o m e s available to plants at a faster rate, which in turn means better plant growth, MAF's Agrisearch magazine reports. When phosphate fertilisers are spread, a certain amount of the phosphate contained in them is prevented from getting to the roots of the plant because of interference from the soil. This phenomenon is called fixation. Reactive soil particles, perhaps clay or organic matter, fix phosphorous, preventing it from moving down the soil profile. By mixing rock phosphate with soluble phosphates, scientists think the two somehow react to prevent this. It is also possible that as the soluble phosphate dissolves, it produces an acid. Scientists believe this acid could speed up the process of breaking down the rock phosphate and releasing its nutrients. A third reason for these results could lie with the plant. Researchers think the roots somehow become stimulated by the presence of the two fer-

tilisers, making it more receptive t o phosphate, and better able to exploit it.