Monsanto has reported a 45 per cent drop in net income for the third quarter of the year, and is braced for a "challenging year" ahead.

The seed giant has announced that net profit nearly halved during the third quarter of the year, the result of falling sales in its herbicide business, which dropped 56 per cent when combined with similar products.

As a result, profit dropped 45 per cent through the quarter to $384 million, down from $694m in the same period a year earlier.

The world's largest seed maker and agricultural chemical producer did see positive movement in its seeds and genomics operation, with net sales climbing five per cent on 2009.

Last year, Monsanto said that it was shifting much of its focus to genetically altered seeds and away from herbicides, with 900 jobs cut from the latter.

"We've made some real changes to our portfolio and business approach, and the positive feedback I'm hearing from our customers tells me we are on the right track," said Hugh Grant, president of Monsanto.

"We have demonstrated agility in the face of adversity, enhancing our portfolio and equipping our sales team with an unprecedented amount of product choices and price points to offer our customers.”

Grant added: "This year has brought its challenges, yet we are quickly evolving into a newer, leaner, stronger Monsanto, well-positioned to meet our objective for mid-teens earnings growth driven by our seeds and traits business.”