Coated urea cuts nitrogen losses in China citrus study

Controlled-release nitrogen fertilizer improved citrus production and cut several types of nitrogen losses in a two-year study in China. The research, published Nov. 1 in Agriculture, Ecosystems & Environment, tested four urea products in an orchard in Yanting County, Sichuan Province.

Polyurethane-coated urea performed best. Over two years it cut ammonia losses by 51.1% and nitric oxide emissions by 36.3% compared with conventional urea. It also reduced nitrate losses in surface runoff by 25.5% and raised fruit yield, though the yield gain was significant only in the second year.

Humic acid urea increased nitrous oxide emissions by 16.1%. A urease inhibitor reduced some losses but did not consistently cut ammonia or nitrous oxide.

The losses were measured in surface runoff, not leaching through soil, so the results do not transfer directly to Florida’s sandy soils, where nitrogen leaching is a concern. Citrus Industry Magazine says field trials under Florida conditions would be needed before any recommendation.

Efficiency gains matter as urea prices in Brazil climb after a thin Indian tender, which keeps nitrogen costs high for growers.

Source: Citrus Industry Magazine