Status And Spatial Variability Characteristic Of Soil Nutrient In New Tobacco Plantation District In Huili

The geostatistics in combination with the traditional statistics were used to study the soil nutrients situation and their spatial variability characteristics of the planned tobacco plantation district soil in Huili County, Liangshan Prefecture in Sichuan Province, and analyze the nutrient synergistic effect, eutrophication risks and the influencing factors. The results were as follows:(1)Except that the variability coefficient of the available iron and copper contents were more than 90%, that of the other nutrients contents were among 10-90%, moderate variability. The contents of the soil available nitrogen, available phosphorus and available potassium were in the moderate or below average level; in more than 20% soil samples, the exchangeable calcium content was from devoid to rich, but in more than 80% samples, exchangeable magnesium content was in the moderate level; available iron, available manganese and soil available zinc contents were rich; in more than 40% soil samples, the soil available copper content was rich; in more than 90% soil samples, the soil water soluble boron and soil water soluble chlorine contents were in the moderate or below average level; while the available molybdenum content was distributed in all the levels.In the study area, the synergistic effect existed among all the nutrients; that between available phosphorus and available potassium was strongest with the correlation coefficient 0.71; and the relatively strong synergistic effect existed among exchangeable calcium and exchangeable magnesium, exchangeable calcium and available manganese. The positive correlation of the available phosphorus, potassium, exchangeable calcium, exchangeable magnesium, soil available copper with the soil nutrients was centralized, with a wide synergistic range.(2)The maximum range was in the available iron to 71100 m and the minimum range appeared in the soil water soluble chlorine to 2740m.The contents of soil exchangeable calcium, exchangeable magnesium, available manganese, soil available zinc and soil water soluble chlorine had strong spatial correlation and the spatial variability was mainly affected by the by structural factors; the contents of soil available nitrogen, available phosphorus, available iron and soil available copper had moderate spatial correlation and their spatial variability was mainly affected by both structural factors and random factors; the soil available potassium content had weak spatial correlation and the spatial variability was mainly affected by the by random factors; the soil water soluble boron and available molybdenum contents had pure nugget effects, and their spatial variability was mainly affected by the by random factors.The contents of the soil available nitrogen, available phosphorus and available potassium decreased from north to south(Henshan Village-Neidong Village-Nange Village);while the contents of exchangeable calcium and exchangeable magnesium demonstrated an opposite trend compared with other nutrients; in the whole study area, the contents of the available iron, available manganese and soil available zinc were in the rich level without apparent variability trend; that of the soil water soluble boron was in the devoid level; that of the soil water soluble chlorine was in the very devoid and devoid levels and the areas of the two levels were similar; the high value area of the available copper mainly distributed in the Nange Village, rich level; and that of the available molybdenum was in the moderate and rich levels, but part of this distributed in the devoid and rich levels.In the study area there was a comparatively high eutrophication probability of the available copper in a big scale(the probability was among 40%-60%,in the high value range).The probability interval range of the available copper was the widest(0-89%), followed by exchangeable calcium(0-58%), available potassium(0-33%), available molybdenum(9%-30%) and available phosphorus(0-14%).(3)Soil pH value had the biggest impact on the exchangeable calcium (correlation coefficient:0.576 and 0.464,respectively); that on the available copper and available manganese contents reached the very significant level, but that on the soil available nitrogen and available potassium contents reached the negatively significant level; the soil organic matters contents had significant or very significant impact on the contents of soil available nitrogen, available phosphorus, available potassium, exchangeable calcium, available iron, available manganese, soil available copper, soil available zinc and soil water soluble boron, respectively, and the maximum impact was on the soil available nitrogen content(correlation coefficient:0.448); cation exchange capacity(CEC) had very significant impact on the contents of soil available phosphorus, exchangeable calcium, exchangeable magnesium and soil available copper, and the maximum impact was on the soil available copper content; for the particle compositions,the clay content had very significant impact on the soil nutrients; the sand content had negative or very significant impact on the soil nutrients; while the silt content had very significant and significant impact on the soil available nitrogen and soil water soluble chlorine, respectively.The difference of the studied nutrients under the four soil types and three terrain conditions did not reach the significant level, but the significant difference and the very significant difference only existed in the particular soil type and terrain condition, which indicated the soil types and the terrain conditions did not had apparent influence on the soil nutrient contents.