Soil Fertility And Plant Nutrition Of Chinese Hickory

In order to understand current soil nutrient conditions for growth of Chinese hickory (Carya cathayensis) and fertilization effecting on its nut yield, soil and plant samples were collected from Chinese hickory plantations in limestone soil lands in DaoShi town of Zhejiang province of China. Results showed that 70% soil pH with pH <6.0, more than 88% soil available phosphorus (P) were lower than 10 mg/kg. Most of plantations were rich in soil organic matter (SOM) content, soil available nitrogen (N) and soil available potassium (K). Soil acidification was serious yet, which is a worsening sign for Chinese hickory growth. Soil pH decreased down to as low as pH 3.6.In general, concentrations of Chinese hickory leaf N, P and K decreased from flowering towards to the mature of nuts regardless of fertilizer topdressings, these suggest that fruit is a strong sink for N, P and K nutrients. It becomes evident to be aware of overdose application of NPK fertilizers, and it is strongly recommended to build up criteria of leaf N, P and K concentrations for optimal growth of Chinese hickory, so that to prevent risk from fertilizer pollution to the environment and to increase fertilizer use efficiency by optimizing fertilizer application for a sustained production of Chinese hickory industry.In addition to the study of the macronutrients, 2 different extraction methods to extract soil available micronutrients of copper (Cu), zinc (Zn), iron (Fe) and mangnese (Mn) were also studied. Soil available micronutrients were either extracted with 0.1 M HCl or boiling-water. Results showed that boiling-water extractable soil micronutrients were significantly correlated with plant leaf concentractions of the corresponding micronutients, whilst not the 0.1 M HCl method. A 2-year field survey revealed that nut yield variation between years could be as high as about 50%, and it differed much more between plantations (from low yield of less than 3 kg/tree to high yield of 9-10 kg/tree).The results indicates that there is an urgent need to optimize soil management of the Chinese hickory plantations to improve soil conditions and so that to maintain production of the Chinese hickory plantations.