Mosaic (NYSE:MOS) — North America's largest phosphate producer — saw its net sales fall to US$2.5 billion in the second quarter of fiscal 2013, down $500 million from last year on the back of lower phosphate and potash volumes and lower phosphate prices, the company announced last week. Sales in the company's phosphate segment, which accounts for the largest share of its revenue, were $1.8 billion in the second quarter, with 3 million metric tons (MT) sold at an average price of $544/MT. The company said that diammonium phosphate fertilizer prices have fallen 11 percent since the same period last year, when FOB prices in Central Florida were $611/MT. Third-quarter phosphate sales are expected to fall to between 2.5 and 2.8 million MT, with prices dropping to between $485 and $515/MT, as most buying is done in advance of the northern planting season, notes Mosaic's report. Falling export sales were the biggest driver of depressed phosphate sales for the Plymouth, Minnesota-based company. Increased domestic sales have cushioned the fall in international demand, despite transportation difficulties due to low water levels on the Mississippi River, a key transportation route to agricultural markets in the US Midwest. Growth lies ahead A number of agricultural producers have recently reported positive earnings and have noted that they expect large spring plantings — of corn, wheat and soybeans in particular — following 2012′s unimpressive crop numbers. St. Louis, Missouri-based Monsanto (NYSE: MON) saw its net income grow by 169 percent, to $339 million, during the first quarter. That growth was the result of corn seed sales — which were hit hard by drought in the US corn belt last year — rising by 25.3 percent. Corn seed sales to South American markets drove profits, with net revenues touching $2.94 billion, 20.5 percent higher than analyst projections. Cargill — the world's biggest agricultural commodities trader — also reported an increase in earnings, gaining more than $300 million since last year to earn $409 million for the quarter ending November 30, 2012. With gains coming from its animal protein section, the company was able to overcome stagnant earnings from its food ingredients section as drought across the US Midwest took its toll on revenues.