| Tea plantation soil was quite important to tea growth as required moisture, nutrients and other substances were mainly absorbed through the soil. Tea plantation soil environmental quality aroused people’s concern, spatial variability and comprehensive evaluation on soil nutrients and the evaluation on environmental quality of soil heavy metal were getting seriously. Study about the level of tea plantation soil fertility and investigation of soil heavy metal could provide a basis of scientific and reasonable precise fertilization, prevention from soil heavy metal pollution, realization of the reasonable use of tea plantation soil resources and protection of agricultural ecological environment.The present study was performed to analysis the spatial variability of soil nutrients of 3 typical green tea plantations in Zhejiang longjing tea producing region by multi-spots sampling in the 4 positions(0-20 cm, 2-40 cm, 40-60 cm and 60-75 cm to tea plant) between tea plant rows with 10 m*15 m grid partition and the analytical means of conventional statistics and geo-statistics and to evaluate the environmental quality of soil heavy metal by the method of single factor pollution index and Nemerow pollution index. The soil fertility indices analyzed consisted of pH, organic materials(OM), total nitrogen(TN), available phosphorus(P), available potassium(K), available calcium(Ca), available magnesium(Mg), available zinc(Zn) and available manganese(Mn). And the heavy metal analyzed consisted of analyzed consisted of arsenic(As), cadmium(Cd), chromium(Cr), mercury(Hg), copper(Cu), nickel(Ni), plumbum(Pb) and zinc(Zn). The results showed that:(1) The tea plantation soil pH value was lower than the standard of high-productive tea plantation soil’s, soil acidification was quite serious.There existed spatial variability of soil fertility indices in different locations between tea plant rows and on the whole of tea plantation. There was a general minimum variation coefficient of soil pH, showed that soil acidity was very stable. The value of soil pH in the location near to fertilization groove inter the two tea plant rows was significantly lower than in the location closed to tea plants in A tea plantation and C tea plantation, and value of soil pH in organic B tea plantation showed the opposite trend. It indicated that the lower value of soil pH had a lot to do with inorganic fertilizer for A long time.The variation coefficient of P was rather bigger among the others, showed strong or stronger spatial variability. The variation coefficients Cd,Cr,Pb,Ni,Cu and zinc was low,which affected by the outside almost consistently, and their space variation was not significant. The variation coefficient of Hg was the largest which was affected mostly by the outside of soil among the 8 measured soil heavy metal,showed the strong or stronger spatial variability.(2) The distributions of different soil fertility indices and heavy metal between tea plant rows were different, which indicated that fertilization had influence on soil fertility indices and heavy metal, but not the same. The distribution of same soil fertility indices and heavy meatl in different tea plantations were not the same.(3) TN in C tea plantation followed logarithmic normal distribution, the rest of the measured tea plantation soil fertility indices all followed the normal distribution. Different soil nutrients and heavy metal had different spatial structure of semivariance function. Theoretical models for semivariogram of soil nutrients best fit included spherical, linear and exponential, differences in the limit distance of spatial correlation and the extent of soil spatial variability were showed.(4) By the means of principal component analysis and correlation analysis, minimum data set of tea plantation soil evaluation were studied, including pH, total nitrogen, available P, available K, and available Mg. The application was pending further research.The correlations among 8 kinds of measured soil heavy metal were varied through the correlation analysis, which indicated that the several kinds of soil heavy metal had inconsistent sources, and maybe came from composite sources. Correlation analysis of soil heavy metal and the physicochemical properties showed that the distribution of heavy affected by the soil pH, organic materials, available phosphorus, total nitrogen and other physicochemical properties.(5) On the whole, belted or block distribution of soil fertility quality studied could been seen in the maps, it had a lot to do with fertilization and terrain. the mean value of 8 kinds of measured soil heavy metal achieved first class of State Environmental Quality Standard for Soils(GB 15618-1995), and the integrated pollution index were all lower than 0.7. The soil environmental quality was in the security level. Pollution of Hg in B tea plantation and C tea plantation were at warming level, likely to be affected by many factors intergratively. Pollution may caused by organic fertilizer application, or other contaminants.C tea plantation was near highway, and may polluted by traffic.(6) The method combined with traditional statistic and GIS to evaluate soil fertility quality had the superiority due to the more intuitive reflection of the space distribution. Suggested to take measures to prevent and control the pollution of soil heavy metal to ensure the quality and efficient of tea production. Such as specification of pesticide and fertilizer use, popularization safety knowledge to the tea farmers and tea producers, monitoring the condition of heavy metal of tea plantation soil. Plant protection forest, isolation belt surrounding tea plantation to provide a safe and clean soil environment for tea production, and to realize the sustainable development of tea. |
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