ROME, ITALY — Prices of global agricultural food commodities declined sharply in July, led lower by steep drops in dairy and sugar, according to the Food and Agriculture Organization of the United Nations.

The FAO Food Price Index averaged 168.8 points in July, down 3.7% from June and down 3.7% from the same period a year ago.

According to the FAO, the decline marked the first significant month-on-month decline in the value of the index since December 2017, reflecting notable drops in the values of all sub-indices.

The FAO Food Price Index is a measure of the monthly change in international prices of a basket of food commodities.

The FAO Cereal Price Index averaged 160.9 points in July, down nearly 6 points, or 3.6%, from June and 1.3 points, or 0.8%, below its level in the corresponding period last year.

“The decline in July was driven by weaker export quotations for wheat, maize and rice,” the FAO noted. “International wheat prices were generally weaker during the first half of the month, but concerns over production prospects in the E.U. and the Russian Federation started to push export values higher toward the end of the month.

“In coarse grains markets, maize prices remained under general downward pressure, largely on weak demand and good production prospects in the United States. However, similar to wheat markets, maize values made solid gains toward the end of the month, on weather worries and a faster pace in export sales. International rice prices also fell, pressured by frail demand for Indica and fragrant varieties as well as currency movements in some leading exporters.”

The FAO Vegetable Oil Price Index averaged 141.9 points in July, down 4.2 points, or 2.9%, from June. The decline marked the sixth consecutive month in which the index has moved lower, and at 141.9 points it was at a two-and-a-half year low, the FAO said.

“The latest slide mostly reflects weakening values of palm oil and soy oil,” the FAO said. “International palm oil prices fell further under the influence of sluggish export demand, ample stocks held by leading producing countries, and expectations of higher production in the coming weeks. As for soy oil, the fresh drop in prices was largely driven by spill-over weakness from the soybean market and persistently high crushing rates in the United States, supported by attractive crush margins. On the other hand, rapeseed oil values trended upward, underpinned by improved demand from biodiesel producers and negative crop prospects in the E.U.”

The FAO Sugar Price Index averaged 166.7 points in July, down 6% from June and nearly 20% lower than a year ago, while the FAO Dairy Price Index averaged 199.1 points, down 6.6% from a month ago and 8% below the same period in 2017.