The researchers studied how different amounts of nitrogen fertilizer and planting densities affect cotton growth in Northeast China. They used two cotton varieties and found that higher nitrogen levels and a specific planting density led to better cotton yield and quality. The cotton plants accumulated nitrogen earlier than biomass, and the best results were seen with a planting density of 97500 plants per hectare and 240 kg of nitrogen per hectare. This information can help farmers in the region improve their cotton production.