| Chinese hickory(Carya cathayensis Sarg.) belongs to Carya Nutt of Juglandaceae. The kernel of Chinese hickory is a reputed healthy food. Its distribution is mainly confined in Tianmu mountain regions in Zhejiang and Anhui provinces of China. In recent years, soil degradation of the Chinese hickory orchards, such as soil acidification and great temporal and spatial variation of nutrients have induced a series of problems, e.g. dieback of the shoot tips and even the death of branches and whole trees, consequently, lowered nut yield of the orchards. Yet detailed research is still lacking. In this study, a3-year long-term field soil investigation and monitoring and pot experiment were carried out to examine soil phosphorus (P) dynamics, P fertilizer effecting Chinese hickory and the risk of soil P potential loss. The critical value for P fertilizer application and threshold value for P leaching, were calculated, so that to provide a scientific guidance for proper P management in Chinese hickory orchards. The main results were as follows:Chinese hickory(Carya cathayensis Sarg.) belongs to Carya Nutt of Juglandaceae. The kernel of Chinese hickory is a reputed healthy food. Its distribution is mainly confined in Tianmu mountain regions in Zhejiang and Anhui provinces of China. In recent years, soil degradation of the Chinese hickory orchards, such as soil acidification and great temporal and spatial variation of nutrients have induced a series of problems, e.g. dieback of the shoot tips and even the death of branches and whole trees, consequently, lowered nut yield of the orchards. Yet detailed research is still lacking. In this study, a3-year long-term field soil investigation and monitoring and pot experiment were carried out to examine soil phosphorus (P) dynamics, P fertilizer effecting Chinese hickory and the risk of soil P potential loss. The critical value for P fertilizer application and threshold value for P leaching, were calculated, so that to provide a scientific guidance for proper P management in Chinese hickory orchards. The main results were as follows:(1) Samples of top layer soil and soil profiles were taken before buds opening in Chinese hickory orchards located at Tuankou, Daoshi and Qingliangfeng towns of Lin’an city to investigate P availability and mobility under long-term fertilizer application. Top layer soil samples at different physiological growth stages of Chinese hickory in Tuankou were also collected to study annual variation of soil P. Results showed that long-term chemical application resulted in serious soil acidification. Soil available P was generally lower and distributed unevenly among different Chinese hichory orchards. Mean soil available P (Olsen-P) was highest in Tuankou, being22.3mg kg-1; and10.5mg kg-1in Daoshi;2.7mg kg-1in Qingliangfeng respectively. Percentage of Chinese hickory orchards with soil available P<5.00mg kg-1were20.0%in Tuankou,66.7%in Daoshi and84.8%in Qingliangfeng. Besides, soil available P in soil profiles showed that P had a tendency of downward movement when soil available P>20mg kg-1. This needs to be aware in case of environmental pollution.(2) Responses of plant growth and P uptake by Chinese hickory seedlings grown in red soil and limestone soil to P application were studied by a pot experiment. Results showed that soil available P in the two soils increased with increasing rate of P application. When P was applied at the same rate, soil available P content in the red soil was higher than that in limestone soil, but the relative increase of soil available P by P application was greater in limestone soil compared with that in red soil. Concentrations of P in leaves of the seedlings also increased with increasing P application rate. Response of leaf P concentrations in plants grown in the limestone soil to P application rate showed more sensitive than that in red soil. At P application rate of40mg kg-1, soil available P in the two soils were closely equal at14mg kg-1, at which leaf P concentrations in the plants grown in the two soils were all up to the maximum of0.58%.(3) Top layer soil samples were also used to assess the potential risk of P leaching under long-term fertilizer application. Soil analysis showed that soil Olsen P had a great spatial variability, being minimum of nearly zero and the maximum up to89.3mg kg-1. There was a significant linear relationship between Olsen P and CaCl2-P:when Olsen P was≥22mg kg-1, CaCl2-P increased with increase of soil Olsen P. Besides, tree foliage P was close to the maximum level when soil Olsen P reached at10mg kg-1. Consequently, soil Olsen P of22mg kg-1was the critical concentration at which leaching of P would happen in the Chinese hickory orchard soils. About32.0%of the investigated orchards was at or above the critical value, and had a risk of P leaching loss from soil to water. |
PDF Full Text Request