Nitrogen Fertilization of Young Chinese Chestnut Trees

Chinese chestnut (Castanea mollissima) is a niche crop in North America. Because the industry is in its infancy, recommendations for many aspects of production are lacking, including optimal rates for nitrogen fertilization. Therefore, a study was conducted to evaluate the effect of five rates of nitrogen on ‘Peach’ Chinese chestnut trees on vegetative growth and fruiting. Young trees received similar rates of nitrogen before the study was initiated. When trees were four years-old, they were fertilized in split applications of nitrogen at 56, 84, 112, 140, or 168 kg/ha on 1 Apr. 1 and 15 June. Treatments were applied to the soil surface below the tree canopy in the form of NH₄NO₃  in 2012 and the area beneath trees received the same treatment in 2013. Foliar sampling on 17 July revealed a linear response to nitrogen treatments.  Foliar N content ranged from 2.17% for the lowest fertilization treatment to 2.47% for the 140 kg N/ha rate.  Most trees began bearing in 2012 with a small crop of chestnuts (< 545 g/tree). Although nut yields were statistically similar for each year, they tended to increase with the rate of nitrogen applied to a maximum of 1347 g/tree for the 140 kg N/ ha treatment in 2013. Nut numbers, terminal shoot growth, and trunk circumference were also similar among treatments in 2013.